| author | prr |
| Mon, 16 May 2011 15:38:56 -0700 | |
| changeset 9655 | e19b80de8a7f |
| parent 5551 | 327690766109 |
| child 14342 | 8435a30053c1 |
| permissions | -rw-r--r-- |
| 2 | 1 |
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Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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<title>JPEG Metadata Format Specification and Usage Notes</title> |
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</head> |
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<body bgcolor="white"> |
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<center><h1> |
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JPEG Metadata Format Specification and Usage Notes |
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</h1></center> |
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<p> |
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<a href=#metadata>JPEG Metadata</a><br> |
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<a href=#abbrev>Abbreviated Streams</a><br> |
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<a href=#tables>Sources of Tables</a><br> |
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<a href=#color>Colorspace Transformations and Conventional Markers</a><br> |
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<a href=#thumbs>Thumbnail Images</a><br> |
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<a href=#prog>Progressive Encoding</a><br> |
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<a href=#tree>Native Metadata Format Tree Structure and Editing</a><br> |
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<a href=#image>Image Metadata DTD</a><br> |
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<a href=#stream>Stream Metadata DTD</a> |
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<p> |
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<bold>NOTE</bold>: It is important to call <code>dispose()</code> |
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on the JPEG reader and writer objects when they are no longer needed, as |
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they consume significant native resources which are not adequately recovered |
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by garbage collection. Both reader and writer call <code>dispose()</code> |
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in their finalizers, but those finalizers may not be called before the native |
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code has exhausted native memory. |
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<p> |
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The JPEG writer does not support replacing pixels. |
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<p> |
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<h2> |
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<a name=metadata>JPEG Metadata</a> |
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</h2> |
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JPEG metadata consists of the data contained in marker segments in a JPEG |
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stream. The image metadata object returned from a read describes the |
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contents of the marker segments between the <code>SOI</code> marker and |
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the <code>EOI</code> marker for that image. The image metadata object |
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passed into a write determines the contents of the stream between the |
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<code>SOI</code> marker and the <code>EOI</code> marker for that image, |
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subject to the controls in any <code>ImageWriteParam</code>. |
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<p> |
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Stream metadata is used only for tables-only images found (or to be |
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placed) at the beginning of a stream containing abbreviated images. |
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Tables-only images are not treated as images and do not consume an |
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image index. The stream metadata object returned from a read describes the |
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contents of the marker segments between the <code>SOI</code> marker and |
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the <code>EOI</code> marker for the single tables-only image at the |
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beginning of the stream, if one is present. If no tables-only image is |
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present at the front of the stream, the <code>getStreamMetadata</code> |
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method of <code>ImageReader</code> returns <code>null</code>. If |
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stream metadata is provided to the writer, a single tables-only image |
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containing the tables from the stream metadata object will be written at |
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the beginning of the stream. If the stream metadata object contains no |
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tables, default tables will be written. As the sole purpose of stream |
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metadata is for specifying tables-only images at the front of abbreviated |
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streams, the stream metadata argument is useful only on the |
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<code>ImageWriter.prepareWriteSequence</code> method. It is ignored on all |
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other methods. |
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<p> |
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The <code>ImageWriter.getDefaultStreamMetadata</code> method returns an |
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object containing the tables from the <code>ImageWriteParam</code> argument, |
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if it is a <code>JPEGImageWriteParam</code> and contains tables. Otherwise, |
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the returned object will contain default tables. |
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<p>The <code>ImageWriter.getDefaultImageMetadata</code> method returns a |
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metadata object containing <bold>no</bold> tables if the |
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<code>ImageWriteParam</code> argument contains tables. Otherwise the |
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returned metadata object will contain default visually lossless tables. |
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Of course, only a <code>JPEGImageWriteParam</code> may contain tables. |
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<p> |
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If <code>ignoreMetadata</code> is set to <code>true</code> when the input |
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is set on the reader, stream metadata will not be available, but image |
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metadata will. |
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<p> |
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<h2> |
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<a name=abbrev>Abbreviated Streams</a> |
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</h2> |
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Both the reader and the writer retain their tables from one operation to the |
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next, thus permitting the use of abbreviated streams quite naturally, with a |
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few minor restrictions: |
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<ol> |
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<li> Abbreviated streams may contain only one tables-only image, which must |
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come first in the stream. Subsequent tables-only images will cause |
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undefined behavior.</li> |
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<li> Abbreviated streams must be read fully and in order. No random access |
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is allowed, in either direction. The same image may be read multiple |
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times. If a call is made with an image index that is not the same as |
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or one greater than the most recent call (or 0 if no calls have been |
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made), then an <code>IllegalArgumentException</code> is thrown.</li> |
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</ol> |
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These restrictions mean that streams may contain abbreviated images |
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interspersed with images containing tables. As required by JPEG, any tables |
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appearing in the stream override previous tables, regardless of the source |
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of the previous tables. |
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<p> |
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Note that once a tables-only image has been read, it's contents is available |
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as stream metadata from the reader until either another tables-only image |
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is read from another stream or the reader is reset. Changing the input does |
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not reset the stream metadata. This is useful for reading the tables from |
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one file, then changing the input to read an abbreviated stream containing |
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a sequence of images. The tables will be used automatically, and will remain |
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available as "stream" metadata. |
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<p> |
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Abbreviated streams are written using the sequence methods of |
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<code>ImageWriter</code>. Stream metadata is used to write a tables-only |
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image at the beginning of the stream, and the tables are set up for use, using |
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<code>ImageWriter.prepareWriteSequence</code>. If no stream metadata is |
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supplied to <code>ImageWriter.prepareWriteSequence</code>, then no |
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tables-only image is written. If stream metadata containing no tables is |
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supplied to <code>ImageWriter.prepareWriteSequence</code>, then a tables-only |
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image containing default visually lossless tables is written. |
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<h2> |
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<a name=tables>Sources of Tables</a> |
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</h2> |
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<p> |
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Images are written with tables if tables are present in their metadata objects |
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or without them if no tables are present in their metadata objects. If no |
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metadata object is present then the tables are written. The tables used for |
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compression are taken from one of the following sources, which are consulted |
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in order: |
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<ol> |
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<li> If there is an <code>ImageWriteParam</code> and the compression mode is |
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set to <code>EXPLICIT</code>, default tables constructed using the |
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quality setting are used. They are written only if the metadata |
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contains tables or if there is no metadata, but they replace the |
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tables in the metadata.</li> |
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<li> If there is an <code>ImageWriteParam</code> and the compression mode is |
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set to <code>DEFAULT</code>, default visually lossles tables are used. |
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They are written only if the metadata contains tables or if |
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there is no metadata, but they replace the tables in the |
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metadata.</li> |
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<li> Otherwise the compression mode on the <code>ImageWriteParam</code> must |
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be MODE_COPY_FROM_<code>METADATA</code>, in which case the following |
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are used: |
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<ol> |
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<li> the tables in the image metadata, if present</li> |
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<li> the tables in the stream metadata, if present</li> |
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<li> the tables in the <code>JPEGImageWriteParam</code>, if present</li> |
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<li> default visually lossless tables</li> |
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</ol> Tables are written only if they are taken from image metadata. |
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</li> |
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</ol> |
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This ordering implements the design intention that tables should be included |
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in <code>JPEGImageWriteParam</code>s only as a means of specifying tables |
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when no other source is available, and this can occur only when writing to an |
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abbreviated stream without tables using known non-standard tables for |
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compression. |
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<p> |
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When reading, tables in a <code>JPEGImageReadParam</code> are consulted only |
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if tables have not been set by any previous read. Tables set from a |
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<code>JPEGImageReadParam</code> are overridden by any tables present in the |
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stream being read. |
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<p> |
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Note that if no image metadata object is specified for a particular image, a |
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default object is used, which includes default tables. |
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<p> |
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<h2> |
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<a name=color>Colorspace Transformations and Conventional Markers</a> |
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</h2> |
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Colorspace transformations are controlled by the destination type for |
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both reading and writing of images. When <code>Raster</code>s are |
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read, no colorspace transformation is performed, and any destination type |
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is ignored. A warning is sent to any listeners if a destination type is |
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specified in this case. When <code>Raster</code>s are written, any |
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destination type is used to interpret the bands. This might result in a |
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JFIF or Adobe header being written, or different component ids being written |
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to the frame and scan headers. If values present in a metadata object do not |
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match the destination type, the destination type is used and a warning is sent |
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to any listeners. |
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<p> |
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<a name=optcolor><b>Optional ColorSpace support:</b></a> |
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Handling of PhotoYCC (YCC), PhotoYCCA (YCCA), RGBA and YCbCrA color spaces |
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by the standard plugin, as described below, is dependent on capabilities |
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of the libraries used to interpret the JPEG data. Thus all consequential |
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behaviors are optional. If the support is not available when decoding, |
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the color space will be treated as unrecognized and the appropriate |
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default color space for the specified number of component channels |
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may be used. |
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When writing, an Exception may be thrown if no suitable conversion |
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can be applied before encoding. |
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But where the support for these color spaces is available, the behavior |
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must be as documented. |
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<p> |
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When reading, the contents of the stream are interpreted by the usual |
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JPEG conventions, as follows: |
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<ul> |
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<li> If a JFIF <code>APP0</code> marker segment is present, the colorspace |
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is known to be either grayscale or YCbCr. If an <code>APP2</code> |
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marker segment containing an embedded ICC profile is also present, then |
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the YCbCr is converted to RGB according to the formulas given in the |
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JFIF spec, and the ICC profile is assumed to refer to the resulting RGB |
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space. |
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<p> |
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<li> If an Adobe <code>APP14</code> marker segment is present, the |
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colorspace is determined by consulting the <code>transform</code> flag. |
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The <code>transform</code> flag takes one of three values: |
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<ul> |
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<li> 2 - The image is encoded as YCCK (implicitly converted from |
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CMYK on encoding). |
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<li> 1 - The image is encoded as YCbCr (implicitly converted from RGB |
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on encoding). |
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<li> 0 - Unknown. 3-channel images are assumed to be RGB, 4-channel |
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images are assumed to be CMYK. |
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</ul> |
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<p> |
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<li> If neither marker segment is present, the following procedure is |
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followed: Single-channel images are assumed to be grayscale, and |
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2-channel images are assumed to be grayscale with an alpha channel. |
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For 3- and 4-channel images, the component ids are consulted. If these |
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values are 1-3 for a 3-channel image, then the image is assumed to be |
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YCbCr. Subject to the availability of the |
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<a href=#optcolor>optional color space support</a> |
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described above, if these values are 1-4 for a 4-channel image, |
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then the image is assumed to be YCbCrA. |
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If these values are > 4, they are checked |
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against the ASCII codes for 'R', 'G', 'B', 'A', 'C', 'c'. These can |
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encode the following colorspaces: |
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<p> |
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<br>RGB |
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<br>RGBA |
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<br>YCC (as 'Y','C','c'), assumed to be PhotoYCC |
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<br>YCCA (as 'Y','C','c','A'), assumed to be PhotoYCCA |
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<p> |
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Otherwise, 3-channel subsampled images are assumed to be YCbCr, |
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3-channel non-subsampled images are assumed to be RGB, 4-channel |
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subsampled images are assumed to be YCCK, and 4-channel, non-subsampled |
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images are assumed to be CMYK. |
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<p> |
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<li> All other images are declared uninterpretable and an exception is |
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thrown if an attempt is made to read one as a |
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<code>BufferedImage</code>. Such an image may be read only as a |
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<code>Raster</code>. If an image is interpretable but there is no Java |
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<code>ColorSpace</code> available corresponding to the encoded |
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colorspace (<italic>e.g.</italic> YCbCr), then |
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<code>ImageReader.getRawImageType</code> will return <code>null</code>. |
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</ul> |
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Once an encoded colorspace is determined, then the target colorspace is |
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determined as follows: |
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<ul> |
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<li> If a destination type is not set, then the following default |
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transformations take place after upsampling: YCbCr (and YCbCrA) images |
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are converted to RGB (and RGBA) using the conversion provided by the |
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underlying IJG library and either the built-in sRGB |
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<code>ColorSpace</code> or a custom RGB <code>ColorSpace</code> object |
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based on an embedded ICC profile is used to create the output |
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<code>ColorModel</code>. PhotoYCC and PhotoYCCA images are not |
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converted. CMYK and YCCK images are currently not supported.</li> |
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<li> If a destination image or type is set, it is used as follows: |
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If the IJG library provides an appropriate conversion, it is used. |
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Otherwise the default library conversion is followed by a colorspace |
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conversion in Java.</li> |
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<li> Bands are selected AFTER any library colorspace conversion. If a |
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subset of either source or destination bands is used, then the default |
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library conversions are used with no further conversion in Java, |
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regardless of any destination type.</li> |
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<li> An exception is thrown if an attempt is made to read an image in an |
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unsupported jpeg colorspace as a <code>BufferedImage</code> |
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(<italic>e.g.</italic> CMYK). Such images may be read as |
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<code>Raster</code>s. If an image colorspace is unsupported or |
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uninterpretable, then <code>ImageReader.getImageTypes</code> will |
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return an empty <code>Iterator</code>. If a subset of the raw bands |
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are required, a <code>Raster</code> must be obtained first and the |
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bands obtained from that. </li> |
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</ul> |
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<p> |
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For writing, the color transformation to apply is determined as |
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follows: |
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<p> |
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If a subset of the source bands is to be written, no color conversion is |
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performed. Any destination, if set, must match the number of bands that will |
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be written, and serves as an interpretation of the selected bands, rather than |
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a conversion request. This behavior is identical to that for |
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<code>Raster</code>s. If all the bands are to be written and an image |
|
329 |
(as opposed to a <code>Raster</code>) is being written, any destination type |
|
330 |
is ignored and a warning is sent to any listeners. |
|
331 |
||
332 |
<p> |
|
333 |
If a destination type is used and any aspect of the metadata object, if there |
|
334 |
is one, is not compatible with that type, the destination type is used, the |
|
335 |
metadata written is modified from that provided, and a warning is sent to |
|
336 |
listeners. This includes the <code>app0JFIF</code> and |
|
337 |
<code>app14Adobe</code> nodes. The component ids in the <code>sof</code> and |
|
338 |
<code>sos</code> nodes are not modified, however, as unless a |
|
339 |
<code>app0JFIF</code> node is present, any values may be used. |
|
340 |
<p> |
|
341 |
||
342 |
When a full image is written, a destination colorspace will be |
|
343 |
chosen based on the image contents and the metadata settings, according to |
|
344 |
the following algorithm: |
|
345 |
||
346 |
<p> |
|
347 |
||
348 |
If no metadata object is specified, then the following defaults apply: |
|
349 |
||
350 |
<ul> |
|
351 |
<li> Grayscale images are written with a JFIF <code>APP0</code> marker |
|
352 |
segment. Grayscale images with alpha are written with no special |
|
353 |
marker. As required by JFIF, the component ids in the frame and |
|
354 |
scan header is set to 1. |
|
355 |
||
356 |
<li> RGB images are converted to YCbCr, subsampled in the chrominance |
|
357 |
channels by half both vertically and horizontally, and written with a |
|
358 |
JFIF <code>APP0</code> marker segment. If the <code>ColorSpace</code> |
|
359 |
of the image is based on an <code>ICCProfile</code> (it is an instance |
|
360 |
of <code>ICC_ColorSpace</code>, but is not one of the standard built-in |
|
361 |
<code>ColorSpaces</code>), then that profile is embedded in an |
|
362 |
<code>APP2</code> marker segment. As required by JFIF, the |
|
363 |
component ids in the frame and scan headers are set to 1, 2, and 3. |
|
364 |
||
365 |
||
|
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|
366 |
<li> Subject to the <a href=#optcolor>optional library support</a> |
|
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|
367 |
described above, |
|
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|
368 |
RGBA images are converted to YCbCrA, subsampled in the |
| 2 | 369 |
chrominance channels by half both vertically and horizontally, and |
370 |
written without any special marker segments. The component ids |
|
371 |
in the frame and scan headers are set to 1, 2, 3, and 4. |
|
372 |
||
|
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|
373 |
<li> Subject to the <a href=#optcolor>optional library support</a> |
|
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changeset
|
374 |
described above, |
|
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|
375 |
PhotoYCC and YCCAimages are subsampled by half in the chrominance |
| 2 | 376 |
channels both vertically and horizontally and written with an |
377 |
Adobe <code>APP14</code> marker segment and 'Y','C', and 'c' (and |
|
378 |
'A' if an alpha channel is present) as component ids in the frame |
|
379 |
and scan headers. |
|
380 |
</ul> |
|
381 |
||
382 |
Default metadata objects for these image types will reflect these settings. |
|
383 |
||
384 |
<p> |
|
385 |
||
386 |
If a metadata object is specified, then the number of channels in the |
|
387 |
frame and scan headers must always match the number of bands to be |
|
388 |
written, or an exception is thrown. <code>app0JFIF</code> and |
|
389 |
<code>app14Adobe</code> nodes may appear in the same metadata object only |
|
390 |
if the <code>app14Adobe</code> node indicates YCbCr, and the component ids |
|
391 |
are JFIF compatible (0-2). The various image types are processed in the |
|
392 |
following ways: |
|
393 |
||
394 |
<br> |
|
395 |
||
396 |
(All multi-channel images are subsampled according to the sampling factors |
|
397 |
in the frame header node of the metadata object, regardless of color space.) |
|
398 |
||
399 |
<ul> |
|
400 |
<li> Grayscale Images: |
|
401 |
<ul> |
|
402 |
<li> If an <code>app0JFIF</code> node is present in the metadata object, |
|
403 |
a JFIF <code>APP0</code> marker segment is written. |
|
404 |
<li> If an <code>app14Adobe</code> node is present in the metadata |
|
405 |
object, it is checked for validity (<code>transform</code> must be |
|
406 |
<code>UNKNOWN</code>) and written. |
|
407 |
<li> If neither node is present in the metadata object, no special |
|
408 |
marker segment is written. |
|
409 |
</ul> |
|
410 |
||
411 |
<li> Grayscale Images with an Alpha Channel: |
|
412 |
<ul> |
|
413 |
<li> If an <code>app0JFIF</code> node is present in the metadata object, |
|
414 |
it is ignored and a warning is sent to listeners, as JFIF does not |
|
415 |
support 2-channel images. |
|
416 |
<li> If an <code>app14Adobe</code> node is present in the metadata |
|
417 |
object, it is checked for validity (<code>transform</code> must be |
|
418 |
<code>UNKNOWN</code>) and written. If <code>transform</code> is |
|
419 |
not <code>UNKNOWN</code>, a warning is sent to listeners and the |
|
420 |
correct transform is written. |
|
421 |
<li> If neither node is present in the metadata object, no special |
|
422 |
marker segment is written. |
|
423 |
</ul> |
|
424 |
||
425 |
<li> RGB Images: |
|
426 |
<ul> |
|
427 |
<li> If an <code>app0JFIF</code> node is present in the metadata object, |
|
428 |
the image is converted to YCbCr and written with a JFIF |
|
429 |
<code>APP0</code> marker segment. If the <code>ColorSpace</code> |
|
430 |
of the image is based on a non-standard ICC Profile, then that |
|
431 |
profile is embedded in an <code>APP2</code> marker segment. If the |
|
432 |
<code>ColorSpace</code> is not based on a non-standard ICC Profile, |
|
433 |
but an <code>app2ICC</code> node appears in the metadata, then an |
|
434 |
<code>APP2</code> marker segment is written with the appropriate |
|
435 |
standard profile. Note that the profile must specify an RGB color |
|
436 |
space, as the file must be JFIF compliant. |
|
437 |
||
438 |
<li> If an <code>app14Adobe</code> node is present in the metadata |
|
439 |
object, the image is converted according to the color transform |
|
440 |
setting and written with an Adobe <code>APP14</code> marker |
|
441 |
segment. Component ids are written just as they appear in the |
|
442 |
frame and scan headers. The color transform must be either YCbCr |
|
443 |
or <code>UNKNOWN</code>. If it is <code>UNKNOWN</code>, the image |
|
444 |
is not color converted. |
|
445 |
||
446 |
<li> If neither node is present, the component ids in the frame |
|
447 |
header are consulted. If these indicate a colorspace as described |
|
448 |
above, then the image is converted to that colorspace if possible. |
|
449 |
If the component ids do not indicate a colorspace, then the |
|
450 |
sampling factors are consulted. If the image is to be subsampled, |
|
451 |
it is converted to YCbCr first. If the image is not to be |
|
452 |
subsampled, then no conversion is applied. No special marker |
|
453 |
segmentss are written. |
|
454 |
</ul> |
|
455 |
||
456 |
<li> RGBA images: |
|
|
9655
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7044682: Image I/O JPEG Metadata spec. should document that PhotoYCC ColorSpace interpretation is optional.
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parents:
5551
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changeset
|
457 |
Subject to the <a href=#optcolor>optional library support</a> |
|
e19b80de8a7f
7044682: Image I/O JPEG Metadata spec. should document that PhotoYCC ColorSpace interpretation is optional.
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changeset
|
458 |
described above, |
| 2 | 459 |
<ul> |
460 |
<li> If an <code>app0JFIF</code> node is present in the metadata object, |
|
461 |
it is ignored and a warning is sent to listeners, as JFIF does not |
|
462 |
support 4-channel images. |
|
463 |
||
464 |
<li> If an <code>app14Adobe</code> node is present in the metadata |
|
465 |
object, the image is written with an Adobe <code>APP14</code> marker |
|
466 |
segment. No colorspace conversion is performed. Component ids |
|
467 |
are written just as they appear in the frame and scan headers. |
|
468 |
The color transform must be <code>UNKNOWN</code>. If it is |
|
469 |
not, a warning is sent to listeners. |
|
470 |
||
471 |
<li> If no <code>app14Adobe</code> node is present, the component ids in |
|
472 |
the frame header are consulted. If these indicate a colorspace as |
|
473 |
described above, then the image is converted to that colorspace if |
|
474 |
possible. If the component ids do not indicate a colorspace, then |
|
475 |
the sampling factors are consulted. If the image is to be |
|
476 |
subsampled, it is converted to YCbCrA. If the image is not to be |
|
477 |
subsampled, then no conversion is applied. No special marker |
|
478 |
segments are written. |
|
479 |
</ul> |
|
480 |
||
481 |
<li> PhotoYCC Images: |
|
|
9655
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changeset
|
482 |
Subject to the <a href=#optcolor>optional library support</a> |
|
e19b80de8a7f
7044682: Image I/O JPEG Metadata spec. should document that PhotoYCC ColorSpace interpretation is optional.
prr
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5551
diff
changeset
|
483 |
described above, |
| 2 | 484 |
<ul> |
485 |
<li> If an <code>app0JFIF</code> node is present in the metadata object, |
|
486 |
the image is converted to sRGB, and then to YCbCr during encoding, |
|
487 |
and a JFIF <code>APP0</code> marker segment is written. |
|
488 |
||
489 |
<li> If an <code>app14Adobe</code> node is present in the metadata |
|
490 |
object, no conversion is applied, and an Adobe <code>APP14</code> |
|
491 |
marker segment is written. The color transform must be YCC. If it |
|
492 |
is not, a warning is sent to listeners. |
|
493 |
||
494 |
<li> If neither node is present in the metadata object, no conversion |
|
495 |
is applied, and no special marker segment is written. |
|
496 |
</ul> |
|
497 |
||
498 |
<li> PhotoYCCA Images: |
|
|
9655
e19b80de8a7f
7044682: Image I/O JPEG Metadata spec. should document that PhotoYCC ColorSpace interpretation is optional.
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parents:
5551
diff
changeset
|
499 |
Subject to the <a href=#optcolor>optional library support</a> |
|
e19b80de8a7f
7044682: Image I/O JPEG Metadata spec. should document that PhotoYCC ColorSpace interpretation is optional.
prr
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5551
diff
changeset
|
500 |
described above, |
| 2 | 501 |
<ul> |
502 |
<li> If an <code>app0JFIF</code> node is present in the metadata object, |
|
503 |
it is ignored and a warning is sent to listeners, as JFIF does not |
|
504 |
support 4-channel images. |
|
505 |
||
506 |
<li> If an <code>app14Adobe</code> node is present in the metadata |
|
507 |
object, no conversion is applied, and an Adobe <code>APP14</code> |
|
508 |
marker segment is written. The color transform must be |
|
509 |
<code>UNKNOWN</code>. If it is not, a warning is sent to |
|
510 |
listeners. |
|
511 |
||
512 |
<li> If neither node is present in the metadata object, no conversion |
|
513 |
is applied, and no special marker segment is written. |
|
514 |
</ul> |
|
515 |
</ul> |
|
516 |
||
517 |
<p> |
|
518 |
<h2> |
|
519 |
<a name=thumbs>Thumbnail Images</a> |
|
520 |
</h2> |
|
521 |
Thumbnails are supported by the use of JFIF and JFIF extension marker segments. |
|
522 |
Thumbnails provided on the write methods determine the thumbnails that will be |
|
523 |
included. <code>app0JFIF</code> and <code>app0JFXX</code> nodes present in |
|
524 |
the metadata do not contain any thumbnail pixel data. However, the kinds of |
|
525 |
thumbnails written depend on the contents of the metadata object, as follows. |
|
526 |
Any thumbnail which is to be written as an indexed or RGB image and which is |
|
527 |
larger than 255 by 255 will be clipped, not scaled, to 255 by 255. Thumbnails |
|
528 |
written as JPEG images may be any size. A warning is sent to any listeners |
|
529 |
whenever a thumbnail is clipped. |
|
530 |
<ul> |
|
531 |
<li> If there is a single thumbnail, it is processed as follows: |
|
532 |
<ul> |
|
533 |
<li> If the thumbnail image is an RGB palette image, it is processed as |
|
534 |
follows: |
|
535 |
<ul> |
|
536 |
<li> If no <code>app0JFXX</code> node is present in the metadata, or |
|
537 |
the first <code>app0JFXX</code> node present in the metadata |
|
538 |
contains a <code>JFIFthumbPalette</code> element, a |
|
539 |
palette thumbnail is written in a JFXX <code>APP0</code> marker |
|
540 |
segment. |
|
541 |
<li> If the first <code>app0JFXX</code> node present in the metadata |
|
542 |
contains another thumbnail form (RGB or JPEG), the palette |
|
543 |
image is expanded to RGB and the indicated thumbnail form is |
|
544 |
written. |
|
545 |
</ul> |
|
546 |
||
547 |
<li> If the thumbnail image is an RGB image, it is processed as follows: |
|
548 |
<ul> |
|
549 |
<li> If no <code>app0JFXX</code> node is present in the metadata, |
|
550 |
the thumbnail is written as part of the JFIF <code>APP0</code> |
|
551 |
marker segment. |
|
552 |
<li> If the first <code>app0JFXX</code> node present in the metadata |
|
553 |
contains a <code>JFIFthumbRGB</code> element, an |
|
554 |
RGB thumbnail is written in a JFXX <code>APP0</code> marker |
|
555 |
segment. |
|
556 |
<li> If the first <code>app0JFXX</code> node present in the metadata |
|
557 |
contains a <code>JFIFthumbJPEG</code> element, a |
|
558 |
JPEG thumbnail is written in a JFXX <code>APP0</code> marker |
|
559 |
segment. |
|
560 |
<li> If the first <code>app0JFXX</code> node present in the metadata |
|
561 |
contains a <code>JFIFthumbPalette</code> element, an |
|
562 |
RGB thumbnail is written in a JFXX <code>APP0</code> marker |
|
563 |
segment and a warning is sent to any listeners. |
|
564 |
</ul> |
|
565 |
||
566 |
<li> If the thumbnail image is a grayscale image, it is processed as |
|
567 |
follows: |
|
568 |
<ul> |
|
569 |
<li> If no <code>app0JFXX</code> node is present in the metadata, |
|
570 |
the thumbnail is expanded to RGB and written as part of the |
|
571 |
JFIF <code>APP0</code> marker segment. |
|
572 |
<li> If the first <code>app0JFXX</code> node present in the metadata |
|
573 |
contains a <code>JFIFthumbRGB</code> element, the thumbnail is |
|
574 |
expanded to RGB and written in a separate <code>JFXX</code> RGB |
|
575 |
marker segment. |
|
576 |
<li> If the first <code>app0JFXX</code> node present in the metadata |
|
577 |
contains a <code>JFIFthumbJPEG</code> element, a |
|
578 |
JPEG thumbnail is written in a JFXX <code>APP0</code> marker |
|
579 |
segment. |
|
580 |
<li> If the first <code>app0JFXX</code> node present in the metadata |
|
581 |
contains a <code>JFIFthumbPalette</code> element, a |
|
582 |
JPEG thumbnail is written in a JFXX <code>APP0</code> marker |
|
583 |
segment and a warning is sent to any listeners. |
|
584 |
</ul> |
|
585 |
||
586 |
<li> Any other thumbnail image types are ignored and a warning is sent |
|
587 |
to any listeners. |
|
588 |
</ul> |
|
589 |
||
590 |
<li> If there are multiple thumbnails, each one is processed as above, except |
|
591 |
that no thumbnail is placed in the JFIF <code>APP0</code> segment, and |
|
592 |
the <code>app0JFXX</code> node consulted for each thumbnail is the |
|
593 |
<code>app0JFXX</code> node from the metadata that occurs in the same |
|
594 |
sequence as the thumbnail. <italic>I.e.</italic> the first |
|
595 |
<code>app0JFXX</code> node applies to the first thumbnail, the second |
|
596 |
node to the second thumbnail, and so on. If there are fewer |
|
597 |
<code>app0JFXX</code> nodes in the metadata than thumbnails, then |
|
598 |
those thumbnails are considered to have no matching |
|
599 |
<code>app0JFXX</code> node. An RGB thumbnail with no matching |
|
600 |
<code>app0JFXX</code> node is written in a JFXX <code>APP0</code> marker |
|
601 |
segment. A grayscale thumbnail with no matching |
|
602 |
<code>app0JFXX</code> node is written as a JPEG image to a JFXX |
|
603 |
<code>APP0</code> marker segment. |
|
604 |
</ul> |
|
605 |
<p> |
|
606 |
||
607 |
Note that as the only mechanism for storing thumbnails is via the |
|
608 |
JFIF or JFIF extension marker segments, only grayscale or RGB images |
|
609 |
may have thumbnails. If thumbnails are present when writing any other type |
|
610 |
of image, the thumbnails are ignored and a warning is sent to any warning |
|
611 |
listeners. |
|
612 |
||
613 |
<p> |
|
614 |
<h2> |
|
615 |
<a name=prog>Progressive Encoding</a> |
|
616 |
</h2> |
|
617 |
||
618 |
Progressive encoding must be enabled on the <code>ImageWriteParam</code> |
|
619 |
passed in to a write operation, or the image will be written sequentially, |
|
620 |
regardless of the scan headers included in the metadata object. If |
|
621 |
progressive encoding is enabled and set to copy from metadata, then |
|
622 |
the sequence of scan headers from the metadata is used to write the |
|
623 |
image. If progressive encoding is enabled and set to use a default, |
|
624 |
then the scans in the metadata are ignored and a default set of scans |
|
625 |
is used. Progressive encoding always forces optimized Huffman tables to |
|
626 |
be used. Any Huffman tables present in the metadata will be ignored, |
|
627 |
and a warning will be sent to any warning listeners. |
|
628 |
||
629 |
If Huffman-table optimization is requested on the <code>ImageWriteParam</code>, |
|
630 |
all Huffman tables in the metadata or in the <code>ImageWriteParam</code> |
|
631 |
itself are ignored, and a warning will be sent to any warning listeners if |
|
632 |
any such tables are present. |
|
633 |
||
634 |
<p> |
|
635 |
<h2> |
|
636 |
<a name=tree>Native Metadata Format Tree Structure and Editing</a> |
|
637 |
</h2> |
|
638 |
||
639 |
The DTDs below describe just the trees of metadata objects actually returned |
|
640 |
by the <code>IIOMetadata</code> object. They do not include nodes |
|
641 |
corresponding to <code>SOI</code>, <code>EOI</code>, or <code>RST</code> |
|
642 |
markers, as these parsing delimiters do not carry any meaningful metadata. |
|
643 |
<p> |
|
644 |
||
645 |
The first node is always a <code>JPEGvariety</code> node. In the |
|
646 |
<code>javax_imageio_jpeg_image_1.0</code> version of the JPEG metadata |
|
647 |
format, this node may have one child, an <code>app0JFIF</code> node, |
|
648 |
indicating that the JPEG stream contains a JFIF marker segment and related |
|
649 |
data, or no children, indicating that the stream contains no JFIF marker. |
|
650 |
In future versions of the JPEG metadata format, other varieties of JPEG |
|
651 |
metadata may be supported (e.g. Exif) by defining other types of nodes |
|
652 |
which may appear as a child of the <code>JPEGvariety</code> node. |
|
653 |
<p> |
|
654 |
||
655 |
(Note that an application wishing to interpret Exif metadata given |
|
656 |
a metadata tree structure in the <code>javax_imageio_jpeg_image_1.0</code> |
|
657 |
format must check for an <code>unknown</code> marker segment with a tag |
|
658 |
indicating an <code>APP1</code> marker and containing data identifying it |
|
659 |
as an Exif marker segment. Then it may use application-specific code to |
|
660 |
interpret the data in the marker segment. If such an application were |
|
661 |
to encounter a metadata tree formatted according to a future version of |
|
662 |
the JPEG metadata format, the Exif marker segment might not be |
|
663 |
<code>unknown</code> in that format - it might be structured as a |
|
664 |
child node of the <code>JPEGvariety</code> node. Thus, it is important |
|
665 |
for an application to specify which version to use by passing the string |
|
666 |
identifying the version to the method/constructor used to obtain an |
|
667 |
<code>IIOMetadata</code> object.) |
|
668 |
||
669 |
<p> |
|
670 |
||
671 |
On reading, <code>JFXX</code> and <code>app2ICC</code> nodes occur as |
|
672 |
children of an <code>app0JFIF</code> node. |
|
673 |
This is true regardless of where the JFXX <code>APP0</code> and |
|
674 |
<code>APP2</code> marker segments actually occur in the stream. The ordering |
|
675 |
of nodes within the <code>markerSequence</code> node corresponds to the |
|
676 |
ordering of marker segments found in the JPEG stream. |
|
677 |
<p> |
|
678 |
On writing, any <code>JFXX</code> and <code>app2ICC</code> nodes must |
|
679 |
occur as children of an <code>app0JFIF</code> node, itself a child of a |
|
680 |
<code>JPEGvariety</code> node, which must always be the first node. |
|
681 |
(If the stream is not to be JFIF compliant, no <code>app0JFIF</code> node |
|
682 |
should be provided, and the <code>JPEGvariety</code> node should have no |
|
683 |
children.) Any |
|
684 |
JFIF <code>APP0</code>, JFXX <code>APP0</code>, and <code>APP2</code> marker |
|
685 |
segments are written first, followed by all Adobe <code>APP14</code>, |
|
686 |
<code>APPn</code>, <code>COM</code> and unknown segments in the |
|
687 |
order in which their corresponding nodes appear in the |
|
688 |
<code>markerSequence</code> node, followed by <code>DQT</code> (and |
|
689 |
<code>DHT</code> for non-progressive writes) marker segments, followed by the |
|
690 |
<code>SOF</code> and <code>SOS</code> marker segments. For progressive writes |
|
691 |
using metadata to control progression, the <code>SOS</code> segments are used |
|
692 |
in the order in which their corresponding nodes occur in the |
|
693 |
<code>markerSequence</code> node. |
|
694 |
<p> |
|
695 |
||
696 |
The <code>reset</code>, <code>mergeTree</code> and <code>setFromTree</code> |
|
697 |
operations have the following semantics for the JPEG plug-in metadata object: |
|
698 |
||
699 |
<p> <code>reset</code> - A call to <code>reset</code> will restore the |
|
700 |
metadata object to the same state it had immediately after creation, whether |
|
701 |
this came about from reading a stream or by obtaining a default object from |
|
702 |
the <code>ImageWriter</code>. This is true regardless of how many times the |
|
703 |
metadata object has been modified since creation. |
|
704 |
||
705 |
<p> <code>mergeTree</code> - Native Format |
|
706 |
<br> The <code>mergeTree</code> operation accepts valid trees conforming to |
|
707 |
the DTD below, and merges the nodes using the following ordering rules. In |
|
708 |
all cases, only data present in the new node is changed in a corresponding |
|
709 |
existing node, if any. This means that nodes cannot be removed using |
|
710 |
<code>mergeTree</code>. To remove nodes, use <code>setFromTree</code>. The |
|
711 |
tree must consist of <code>IIOMetadataNode</code>s. |
|
712 |
<ul> |
|
713 |
<li> <code>app0JFIF</code> |
|
714 |
<ul> |
|
715 |
<li> If an <code>app0JFIF</code> node already exists, the contents |
|
716 |
of the new one modify the existing one. |
|
717 |
<li> If there is no such node, a new one is created and inserted in |
|
718 |
the appropriate position. |
|
719 |
</ul> |
|
720 |
<li> <code>dqt</code> |
|
721 |
<ul> |
|
722 |
<li> If there already exist <code>dqt</code> nodes in the sequence, |
|
723 |
then each table in the node replaces the first table, in any |
|
724 |
<code>dqt</code> node, with the same table id. |
|
725 |
<li> If none of the existing <code>dqt</code> nodes contain a table |
|
726 |
with the same id, then the table is added to the last existing |
|
727 |
<code>dqt</code> node. |
|
728 |
<li> If there are no <code>dqt</code> nodes, then a new one is |
|
729 |
created and added as follows: |
|
730 |
<ul> |
|
731 |
<li> If there are <code>dht</code> nodes, the new |
|
732 |
<code>dqt</code> node is inserted before the first one. |
|
733 |
<li> If there are no <code>dht</code> nodes, the new |
|
734 |
<code>dqt</code> node is inserted before an |
|
735 |
<code>sof</code> node, if there is one. |
|
736 |
<li> If there is no <code>sof</code> node, the new |
|
737 |
<code>dqt</code> node is inserted before the first |
|
738 |
<code>sos</code> node, if there is one. |
|
739 |
<li> If there is no <code>sos</code> node, the new |
|
740 |
<code>dqt</code> node is added to the end of the sequence. |
|
741 |
</ul> |
|
742 |
</ul> |
|
743 |
<li> <code>dht</code> |
|
744 |
<ul> |
|
745 |
<li> If there already exist <code>dht</code> nodes in the sequence, |
|
746 |
then each table in the node replaces the first table, in any |
|
747 |
<code>dht</code> node, with the same table class and table id. |
|
748 |
<li> If none of the existing <code>dht</code> nodes contain a table |
|
749 |
with the same class and id, then the table is added to the last |
|
750 |
existing <code>dht</code> node. |
|
751 |
<li> If there are no <code>dht</code> nodes, then a new one is |
|
752 |
created and added as follows: |
|
753 |
<ul> |
|
754 |
<li> If there are <code>dqt</code> nodes, the new |
|
755 |
<code>dht</code> node is inserted immediately following the |
|
756 |
last <code>dqt</code> node. |
|
757 |
<li> If there are no <code>dqt</code> nodes, the new |
|
758 |
<code>dht</code> node is inserted before an |
|
759 |
<code>sof</code> node, if there is one. |
|
760 |
<li> If there is no <code>sof</code> node, the new |
|
761 |
<code>dht</code> node is inserted before the first |
|
762 |
<code>sos</code> node, if there is one. |
|
763 |
<li> If there is no <code>sos</code> node, the new |
|
764 |
<code>dht</code> node is added to the end of the sequence. |
|
765 |
</ul> |
|
766 |
</ul> |
|
767 |
<li> <code>dri</code> |
|
768 |
<ul> |
|
769 |
<li> If there already exists a <code>dri</code> node, the restart |
|
770 |
interval value is updated. |
|
771 |
<li> If there is no <code>dri</code> node, then a new one is created |
|
772 |
and added as follows: |
|
773 |
<ul> |
|
774 |
<li> If there is an <code>sof</code> node, the new |
|
775 |
<code>dri</code> node is inserted before it. |
|
776 |
<li> If there is no <code>sof</code> node, the new |
|
777 |
<code>dri</code> node is inserted before the first |
|
778 |
<code>sos</code> node, if there is one. |
|
779 |
<li> If there is no <code>sos</code> node, the new |
|
780 |
<code>dri</code> node is added to the end of the sequence. |
|
781 |
</ul> |
|
782 |
</ul> |
|
783 |
<li> <code>com</code> |
|
784 |
<br> A new <code>com</code> node is created and inserted as follows: |
|
785 |
<ul> |
|
786 |
<li> If there already exist <code>com</code> nodes, the new one is |
|
787 |
inserted after the last one. |
|
788 |
<li> If there are no <code>com</code> nodes, the new |
|
789 |
<code>com</code> node is inserted after the |
|
790 |
<code>app14Adobe</code> node, if there is one. |
|
791 |
<li> If there is no <code>app14Adobe</code> node, the new |
|
792 |
<code>com</code> node is inserted at the beginning of the |
|
793 |
sequence. |
|
794 |
</ul> |
|
795 |
<li> <code>app14Adobe</code> |
|
796 |
<ul> |
|
797 |
<li> If there already exists an <code>app14Adobe</code> node, then |
|
798 |
its attributes are updated from the node. |
|
799 |
<li> If there is no <code>app14Adobe</code> node, then a new one is |
|
800 |
created and added as follows: |
|
801 |
<ul> |
|
802 |
<li> The new <code>app14Adobe</code> node is inserted after the |
|
803 |
last <code>unknown</code> node, if there are any. |
|
804 |
<li> If there are no <code>unknown</code> nodes, the new |
|
805 |
<code>app14Adobe</code> node is inserted at the beginning |
|
806 |
of the sequence. |
|
807 |
</ul> |
|
808 |
</ul> |
|
809 |
<li> <code>unknown</code> |
|
810 |
<br> A new <code>unknown</code> node is created and added to the |
|
811 |
sequence as follows: |
|
812 |
<ul> |
|
813 |
<li> If there already exist <code>unknown</code> marker nodes, the |
|
814 |
new one is inserted after the last one. |
|
815 |
<li> If there are no <code>unknown</code> nodes, the new |
|
816 |
<code>unknown</code> node is inserted before the |
|
817 |
<code>app14Adobe</code> node, if there is one. |
|
818 |
<li> If there is no <code>app14Adobe</code> node, the new |
|
819 |
<code>unknown</code> node is inserted at the beginning of the |
|
820 |
sequence. |
|
821 |
</ul> |
|
822 |
<li> <code>sof</code> |
|
823 |
<ul> |
|
824 |
<li> If there already exists an <code>sof</code> node in the |
|
825 |
sequence, then its values are updated from the node. |
|
826 |
<li> If there is no <code>sof</code> node, then a new one is created |
|
827 |
and added as follows: |
|
828 |
<ul> |
|
829 |
<li> If there are any <code>sos</code> nodes, the new |
|
830 |
<code>sof</code> node is inserted before the first one. |
|
831 |
<li> If there is no <code>sos</code> node, the new |
|
832 |
<code>sof</code> node is added to the end of the sequence. |
|
833 |
</ul> |
|
834 |
</ul> |
|
835 |
<li> <code>sos</code> |
|
836 |
<ul> |
|
837 |
<li> If there already exists a single <code>sos</code> node, then |
|
838 |
the values are updated from the node. |
|
839 |
<li> If there are more than one existing <code>sos</code> nodes, |
|
840 |
then an <code>IIOInvalidTreeException</code> is thrown, as |
|
841 |
<code>sos</code> nodes cannot be merged into a set of |
|
842 |
progressive scans. |
|
843 |
<li> If there are no <code>sos</code> nodes, a new one is created |
|
844 |
and added to the end of the sequence. |
|
845 |
</ul> |
|
846 |
</ul> |
|
847 |
||
848 |
<p> <code>mergeTree</code> - Standard Format |
|
849 |
<br> |
|
850 |
The <code>mergeTree</code> operation, when given a tree in the standard |
|
851 |
format, will modify the native tree in the following ways: |
|
852 |
<ul> |
|
853 |
<li> <code>Chroma</code> - The <code>ColorSpaceType</code> subnode of a |
|
854 |
<code>Chroma</code> node may change the target colorspace of the |
|
855 |
compressed image. The selection of a new colorspace can cause a number |
|
856 |
of changes, in keeping with the algorithms described above: |
|
857 |
<code>app0JFIF</code> and <code>app14Adobe</code> nodes may be added |
|
858 |
or removed, subsampling may be added or removed, component ids may |
|
859 |
be changed, and <code>sof</code> and <code>sos</code> nodes will be |
|
860 |
updated accordingly. If necessary, additional quantization and |
|
861 |
huffman tables are added. In the case of quantization tables, the |
|
862 |
default will be scaled to match the quality level of any existing |
|
863 |
tables. No tables are added to metadata that does not already contain |
|
864 |
tables. If the existing metadata specifies progressive encoding, then |
|
865 |
the number of channels must not change. Any <code>Transparency</code> |
|
866 |
node is also taken into account, as an explicit value of |
|
867 |
<code>none</code> for the <code>Alpha</code> subnode can cause the |
|
868 |
removal of an alpha channel, and anything other than <code>none</code> |
|
869 |
can cause the addition of an alpha channel. |
|
870 |
<li> <code>Dimension</code> - A <code>PixelAspectRatio</code> specification |
|
871 |
can cause the contents of an <code>app0JFIF</code> node to change, if |
|
872 |
there is one present, or the addition of an <code>app0JFIF</code> node |
|
873 |
containing appropriate values, if there can be one. An appropriate |
|
874 |
pair of integers is computed from the floating-point ratio for |
|
875 |
inclusion in the node. |
|
876 |
<li> <code>Text</code> - Each uncompressed text item is converted to a |
|
877 |
<code>com</code> node and inserted according to the rules above for |
|
878 |
merging <code>com</code> nodes. |
|
879 |
</ul> |
|
880 |
||
881 |
<p> <code>setFromTree</code> - Native Format |
|
882 |
<br> |
|
883 |
The <code>setFromTree</code> operation, when given a tree in the native |
|
884 |
format described below, will simply replace the existing tree in its entirety |
|
885 |
with the new one. The tree must consist of <code>IIOMetadataNode</code>s. |
|
886 |
||
887 |
<p> <code>setFromTree</code> - Standard Format |
|
888 |
<br> |
|
889 |
The <code>setFromTree</code> operation, when given a tree in the standard |
|
890 |
format, performs a <code>reset</code> followed by a merge of the new tree. |
|
891 |
||
892 |
<h2> |
|
893 |
<a name=image>Image Metadata DTD</a> |
|
894 |
</h2> |
|
895 |
||
896 |
<pre> |
|
897 |
<!DOCTYPE "javax_imageio_jpeg_image_1.0" [ |
|
898 |
||
899 |
<!ELEMENT "javax_imageio_jpeg_image_1.0" (JPEGvariety, markerSequence)> |
|
900 |
||
901 |
<!ELEMENT "JPEGvariety" (app0JFIF)> |
|
902 |
<!-- A node grouping all marker segments specific to the variety of |
|
903 |
stream being read/written (e.g. JFIF) - may be empty --> |
|
904 |
||
905 |
<!ELEMENT "app0JFIF" (JFXX?, app2ICC?)> |
|
906 |
<!ATTLIST "app0JFIF" "majorVersion" #CDATA "1"> |
|
907 |
<!-- The major JFIF version number --> |
|
908 |
<!-- Data type: Integer --> |
|
909 |
<!-- Min value: 0 (inclusive) --> |
|
910 |
<!-- Max value: 255 (inclusive) --> |
|
911 |
<!ATTLIST "app0JFIF" "minorVersion" #CDATA "2"> |
|
912 |
<!-- The minor JFIF version number --> |
|
913 |
<!-- Data type: Integer --> |
|
914 |
<!-- Min value: 0 (inclusive) --> |
|
915 |
<!-- Max value: 255 (inclusive) --> |
|
916 |
<!ATTLIST "app0JFIF" "resUnits" ("0" | "1" | "2") "0">
|
|
917 |
<!-- The resolution units for Xdensisty and Ydensity (0 = no |
|
918 |
units, just aspect ratio; 1 = dots/inch; 2 = dots/cm) --> |
|
919 |
<!ATTLIST "app0JFIF" "Xdensity" #CDATA "1"> |
|
920 |
<!-- The horizontal density or aspect ratio numerator --> |
|
921 |
<!-- Data type: Integer --> |
|
922 |
<!-- Min value: 1 (inclusive) --> |
|
923 |
<!-- Max value: 65535 (inclusive) --> |
|
924 |
<!ATTLIST "app0JFIF" "Ydensity" #CDATA "1"> |
|
925 |
<!-- The vertical density or aspect ratio denominator --> |
|
926 |
<!-- Data type: Integer --> |
|
927 |
<!-- Min value: 1 (inclusive) --> |
|
928 |
<!-- Max value: 65535 (inclusive) --> |
|
929 |
<!ATTLIST "app0JFIF" "thumbWidth" #CDATA "0"> |
|
930 |
<!-- The width of the thumbnail, or 0 if there isn't one --> |
|
931 |
<!-- Data type: Integer --> |
|
932 |
<!-- Min value: 0 (inclusive) --> |
|
933 |
<!-- Max value: 255 (inclusive) --> |
|
934 |
<!ATTLIST "app0JFIF" "thumbHeight" #CDATA "0"> |
|
935 |
<!-- The height of the thumbnail, or 0 if there isn't one --> |
|
936 |
<!-- Data type: Integer --> |
|
937 |
<!-- Min value: 0 (inclusive) --> |
|
938 |
<!-- Max value: 255 (inclusive) --> |
|
939 |
||
940 |
<!ELEMENT "JFXX" (app0JFXX)*> |
|
941 |
<!-- Min children: 1 --> |
|
942 |
||
943 |
<!ELEMENT "app0JFXX" (JFIFthumbJPEG | JFIFthumbPalette | |
|
944 |
JFIFthumbRGB)> |
|
945 |
<!-- A JFIF extension marker segment --> |
|
946 |
<!ATTLIST "app0JFXX" "extensionCode" ("16" | "17" | "19")
|
|
947 |
#IMPLIED> |
|
948 |
<!-- The JFXX extension code identifying thumbnail type: (16 = |
|
949 |
JPEG, 17 = indexed, 19 = RGB --> |
|
950 |
||
951 |
<!ELEMENT "JFIFthumbJPEG" (markerSequence?)> |
|
952 |
<!-- A JFIF thumbnail in JPEG format (no JFIF segments |
|
953 |
permitted) --> |
|
954 |
||
955 |
<!ELEMENT "JFIFthumbPalette" EMPTY> |
|
956 |
<!-- A JFIF thumbnail as an RGB indexed image --> |
|
957 |
<!ATTLIST "JFIFthumbPalette" "thumbWidth" #CDATA #IMPLIED> |
|
958 |
<!-- The width of the thumbnail --> |
|
959 |
<!-- Data type: Integer --> |
|
960 |
<!-- Min value: 0 (inclusive) --> |
|
961 |
<!-- Max value: 255 (inclusive) --> |
|
962 |
<!ATTLIST "JFIFthumbPalette" "thumbHeight" #CDATA #IMPLIED> |
|
963 |
<!-- The height of the thumbnail --> |
|
964 |
<!-- Data type: Integer --> |
|
965 |
<!-- Min value: 0 (inclusive) --> |
|
966 |
<!-- Max value: 255 (inclusive) --> |
|
967 |
||
968 |
<!ELEMENT "JFIFthumbRGB" EMPTY> |
|
969 |
<!-- A JFIF thumbnail as an RGB image --> |
|
970 |
<!ATTLIST "JFIFthumbRGB" "thumbWidth" #CDATA #IMPLIED> |
|
971 |
<!-- The width of the thumbnail --> |
|
972 |
<!-- Data type: Integer --> |
|
973 |
<!-- Min value: 0 (inclusive) --> |
|
974 |
<!-- Max value: 255 (inclusive) --> |
|
975 |
<!ATTLIST "JFIFthumbRGB" "thumbHeight" #CDATA #IMPLIED> |
|
976 |
<!-- The height of the thumbnail --> |
|
977 |
<!-- Data type: Integer --> |
|
978 |
<!-- Min value: 0 (inclusive) --> |
|
979 |
<!-- Max value: 255 (inclusive) --> |
|
980 |
||
981 |
<!ELEMENT "app2ICC" EMPTY> |
|
982 |
<!-- An ICC profile APP2 marker segment --> |
|
983 |
<!-- Optional User object: java.awt.color.ICC_Profile --> |
|
984 |
||
985 |
<!ELEMENT "markerSequence" (dqt | dht | dri | com | unknown | |
|
986 |
app14Adobe | sof | sos)*> |
|
987 |
<!-- A node grouping all non-jfif marker segments --> |
|
988 |
||
989 |
<!ELEMENT "dqt" (dqtable)*> |
|
990 |
<!-- A Define Quantization Table(s) marker segment --> |
|
991 |
<!-- Min children: 1 --> |
|
992 |
<!-- Max children: 4 --> |
|
993 |
||
994 |
<!ELEMENT "dqtable" EMPTY> |
|
995 |
<!-- A single quantization table --> |
|
996 |
<!-- User object: javax.imageio.plugins.jpeg.JPEGQTable --> |
|
997 |
<!ATTLIST "dqtable" "elementPrecision" #CDATA "0"> |
|
998 |
<!-- The number of bits in each table element (0 = 8, 1 = 16) |
|
999 |
--> |
|
1000 |
<!-- Data type: Integer --> |
|
1001 |
<!ATTLIST "dqtable" "qtableId" ("0" | "1" | "2" | "3") #REQUIRED>
|
|
1002 |
||
1003 |
<!ELEMENT "dht" (dhtable)*> |
|
1004 |
<!-- A Define Huffman Table(s) marker segment --> |
|
1005 |
<!-- Min children: 1 --> |
|
1006 |
<!-- Max children: 4 --> |
|
1007 |
||
1008 |
<!ELEMENT "dhtable" EMPTY> |
|
1009 |
<!-- A single Huffman table --> |
|
1010 |
<!-- User object: javax.imageio.plugins.jpeg.JPEGHuffmanTable --> |
|
1011 |
<!ATTLIST "dhtable" "class" ("0" | "1") #REQUIRED>
|
|
1012 |
<!-- Indicates whether this is a DC (0) or an AC (1) table --> |
|
1013 |
<!ATTLIST "dhtable" "htableId" ("0" | "1" | "2" | "3") #REQUIRED>
|
|
1014 |
<!-- The table id --> |
|
1015 |
||
1016 |
<!ELEMENT "dri" EMPTY> |
|
1017 |
<!-- A Define Restart Interval marker segment --> |
|
1018 |
<!ATTLIST "dri" "interval" #CDATA #REQUIRED> |
|
1019 |
<!-- The restart interval in MCUs --> |
|
1020 |
<!-- Data type: Integer --> |
|
1021 |
<!-- Min value: 0 (inclusive) --> |
|
1022 |
<!-- Max value: 65535 (inclusive) --> |
|
1023 |
||
1024 |
<!ELEMENT "com" EMPTY> |
|
1025 |
<!-- A Comment marker segment. The user object contains the actual |
|
1026 |
bytes. --> |
|
1027 |
<!-- User object: array of [B --> |
|
1028 |
<!-- Min length: 1 --> |
|
1029 |
<!-- Max length: 65533 --> |
|
1030 |
<!ATTLIST "com" "comment" #CDATA #IMPLIED> |
|
1031 |
<!-- The comment as a string (used only if user object is null) |
|
1032 |
--> |
|
1033 |
<!-- Data type: String --> |
|
1034 |
||
1035 |
<!ELEMENT "unknown" EMPTY> |
|
1036 |
<!-- An unrecognized marker segment. The user object contains the |
|
1037 |
data not including length. --> |
|
1038 |
<!-- User object: array of [B --> |
|
1039 |
<!-- Min length: 1 --> |
|
1040 |
<!-- Max length: 65533 --> |
|
1041 |
<!ATTLIST "unknown" "MarkerTag" #CDATA #REQUIRED> |
|
1042 |
<!-- The tag identifying this marker segment --> |
|
1043 |
<!-- Data type: Integer --> |
|
1044 |
<!-- Min value: 0 (inclusive) --> |
|
1045 |
<!-- Max value: 255 (inclusive) --> |
|
1046 |
||
1047 |
<!ELEMENT "app14Adobe" EMPTY> |
|
1048 |
<!-- An Adobe APP14 marker segment --> |
|
1049 |
<!ATTLIST "app14Adobe" "version" #CDATA "100"> |
|
1050 |
<!-- The version of Adobe APP14 marker segment --> |
|
1051 |
<!-- Data type: Integer --> |
|
1052 |
<!-- Min value: 100 (inclusive) --> |
|
1053 |
<!-- Max value: 255 (inclusive) --> |
|
1054 |
<!ATTLIST "app14Adobe" "flags0" #CDATA "0"> |
|
1055 |
<!-- The flags0 variable of an APP14 marker segment --> |
|
1056 |
<!-- Data type: Integer --> |
|
1057 |
<!-- Min value: 0 (inclusive) --> |
|
1058 |
<!-- Max value: 65535 (inclusive) --> |
|
1059 |
<!ATTLIST "app14Adobe" "flags1" #CDATA "0"> |
|
1060 |
<!-- The flags1 variable of an APP14 marker segment --> |
|
1061 |
<!-- Data type: Integer --> |
|
1062 |
<!-- Min value: 0 (inclusive) --> |
|
1063 |
<!-- Max value: 65535 (inclusive) --> |
|
1064 |
<!ATTLIST "app14Adobe" "transform" ("0" | "1" | "2") #REQUIRED>
|
|
1065 |
<!-- The color transform applied to the image (0 = Unknown, 1 = |
|
1066 |
YCbCr, 2 = YCCK) --> |
|
1067 |
||
1068 |
<!ELEMENT "sof" (componentSpec)*> |
|
1069 |
<!-- A Start Of Frame marker segment --> |
|
1070 |
<!-- Min children: 1 --> |
|
1071 |
<!-- Max children: 4 --> |
|
1072 |
<!ATTLIST "sof" "process" ("0" | "1" | "2") #IMPLIED>
|
|
1073 |
<!-- The JPEG process (0 = Baseline sequential, 1 = Extended |
|
1074 |
sequential, 2 = Progressive) --> |
|
1075 |
<!ATTLIST "sof" "samplePrecision" #CDATA "8"> |
|
1076 |
<!-- The number of bits per sample --> |
|
1077 |
<!-- Data type: Integer --> |
|
1078 |
<!ATTLIST "sof" "numLines" #CDATA #IMPLIED> |
|
1079 |
<!-- The number of lines in the image --> |
|
1080 |
<!-- Data type: Integer --> |
|
1081 |
<!-- Min value: 0 (inclusive) --> |
|
1082 |
<!-- Max value: 65535 (inclusive) --> |
|
1083 |
<!ATTLIST "sof" "samplesPerLine" #CDATA #IMPLIED> |
|
1084 |
<!-- The number of samples per line --> |
|
1085 |
<!-- Data type: Integer --> |
|
1086 |
<!-- Min value: 0 (inclusive) --> |
|
1087 |
<!-- Max value: 65535 (inclusive) --> |
|
1088 |
<!ATTLIST "sof" "numFrameComponents" ("1" | "2" | "3" | "4")
|
|
1089 |
#IMPLIED> |
|
1090 |
<!-- The number of components in the image --> |
|
1091 |
||
1092 |
<!ELEMENT "componentSpec" EMPTY> |
|
1093 |
<!-- A component specification for a frame --> |
|
1094 |
<!ATTLIST "componentSpec" "componentId" #CDATA #REQUIRED> |
|
1095 |
<!-- The id for this component --> |
|
1096 |
<!-- Data type: Integer --> |
|
1097 |
<!-- Min value: 0 (inclusive) --> |
|
1098 |
<!-- Max value: 255 (inclusive) --> |
|
1099 |
<!ATTLIST "componentSpec" "HsamplingFactor" #CDATA #REQUIRED> |
|
1100 |
<!-- The horizontal sampling factor for this component --> |
|
1101 |
<!-- Data type: Integer --> |
|
1102 |
<!-- Min value: 1 (inclusive) --> |
|
1103 |
<!-- Max value: 255 (inclusive) --> |
|
1104 |
<!ATTLIST "componentSpec" "VsamplingFactor" #CDATA #REQUIRED> |
|
1105 |
<!-- The vertical sampling factor for this component --> |
|
1106 |
<!-- Data type: Integer --> |
|
1107 |
<!-- Min value: 1 (inclusive) --> |
|
1108 |
<!-- Max value: 255 (inclusive) --> |
|
1109 |
<!ATTLIST "componentSpec" "QtableSelector" ("0" | "1" | "2" |
|
|
1110 |
"3") #REQUIRED> |
|
1111 |
<!-- The quantization table to use for this component --> |
|
1112 |
||
1113 |
<!ELEMENT "sos" (scanComponentSpec)*> |
|
1114 |
<!-- A Start Of Scan marker segment --> |
|
1115 |
<!-- Min children: 1 --> |
|
1116 |
<!-- Max children: 4 --> |
|
1117 |
<!ATTLIST "sos" "numScanComponents" ("1" | "2" | "3" | "4")
|
|
1118 |
#REQUIRED> |
|
1119 |
<!-- The number of components in the scan --> |
|
1120 |
<!ATTLIST "sos" "startSpectralSelection" #CDATA "0"> |
|
1121 |
<!-- The first spectral band included in this scan --> |
|
1122 |
<!-- Data type: Integer --> |
|
1123 |
<!-- Min value: 0 (inclusive) --> |
|
1124 |
<!-- Max value: 63 (inclusive) --> |
|
1125 |
<!ATTLIST "sos" "endSpectralSelection" #CDATA "63"> |
|
1126 |
<!-- The last spectral band included in this scan --> |
|
1127 |
<!-- Data type: Integer --> |
|
1128 |
<!-- Min value: 0 (inclusive) --> |
|
1129 |
<!-- Max value: 63 (inclusive) --> |
|
1130 |
<!ATTLIST "sos" "approxHigh" #CDATA "0"> |
|
1131 |
<!-- The highest bit position included in this scan --> |
|
1132 |
<!-- Data type: Integer --> |
|
1133 |
<!-- Min value: 0 (inclusive) --> |
|
1134 |
<!-- Max value: 15 (inclusive) --> |
|
1135 |
<!ATTLIST "sos" "approxLow" #CDATA "0"> |
|
1136 |
<!-- The lowest bit position included in this scan --> |
|
1137 |
<!-- Data type: Integer --> |
|
1138 |
<!-- Min value: 0 (inclusive) --> |
|
1139 |
<!-- Max value: 15 (inclusive) --> |
|
1140 |
||
1141 |
<!ELEMENT "scanComponentSpec" EMPTY> |
|
1142 |
<!-- A component specification for a scan --> |
|
1143 |
<!ATTLIST "scanComponentSpec" "componentSelector" #CDATA |
|
1144 |
#REQUIRED> |
|
1145 |
<!-- The id of this component --> |
|
1146 |
<!-- Data type: Integer --> |
|
1147 |
<!-- Min value: 0 (inclusive) --> |
|
1148 |
<!-- Max value: 255 (inclusive) --> |
|
1149 |
<!ATTLIST "scanComponentSpec" "dcHuffTable" ("0" | "1" | "2" |
|
|
1150 |
"3") #REQUIRED> |
|
1151 |
<!-- The huffman table to use for encoding DC coefficients --> |
|
1152 |
<!ATTLIST "scanComponentSpec" "acHuffTable" ("0" | "1" | "2" |
|
|
1153 |
"3") #REQUIRED> |
|
1154 |
<!-- The huffman table to use for encoding AC coefficients --> |
|
1155 |
]> |
|
1156 |
</pre> |
|
1157 |
||
1158 |
<h2> |
|
1159 |
<a name=stream>Stream Metadata DTD</a> |
|
1160 |
</h2> |
|
1161 |
||
1162 |
<pre> |
|
1163 |
<!DOCTYPE "javax_imageio_jpeg_stream_1.0" [ |
|
1164 |
<!ELEMENT "javax_imageio_jpeg_stream_1.0" (dqt | |
|
1165 |
dht | |
|
1166 |
dri | |
|
1167 |
com | |
|
1168 |
unknown)*> |
|
1169 |
||
1170 |
<!-- All elements are as defined above for image metadata --> |
|
1171 |
]> |
|
1172 |
</pre> |
|
1173 |
||
1174 |
</body> |
|
1175 |
</html> |