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e69dd40c07
- Move all libjpeg documentation, except for README.ijg, into the doc/ subdirectory. - Move the TurboJPEG C API documentation from doc/html/ into doc/turbojpeg/. - Move all C source code and headers into a src/ subdirectory. - Move turbojpeg-jni.c into the java/ subdirectory. Referring to #226, there is no ideal solution to this problem. A semantically ideal solution would have involved placing all source code, including the SIMD and Java source code, under src/ (or perhaps placing C library source code under lib/ and C test program source code under test/), all header files under include/, and all documentation under doc/. However: - To me it makes more sense to have separate top-level directories for each language, since the SIMD extensions and the Java API are technically optional features. src/ now contains only the code that is relevant to the core C API libraries and associated programs. - I didn't want to bury the java/ and simd/ directories or add a level of depth to them, since both directories already contain source code that is 3-4 levels deep. - I would prefer not to separate the header files from the C source code, because: 1. It would be disruptive. libjpeg and libjpeg-turbo have historically placed C source code and headers in the same directory, and people who are familiar with both projects (self included) are used to looking for the headers in the same directory as the C source code. 2. In terms of how the headers are used internally in libjpeg-turbo, the distinction between public and private headers is a bit fuzzy. - It didn't make sense to separate the test source code from the library source code, since there is not a clear distinction in some cases. (For instance, the IJG image I/O functions are used by cjpeg and djpeg as well as by the TurboJPEG API.) This solution is minimally disruptive, since it keeps all C source code and headers together and keeps java/ and simd/ as top-level directories. It is a bit awkward, because java/ and simd/ technically contain source code, even though they are not under src/. However, other solutions would have been more awkward for different reasons. Closes #226
64 lines
1.7 KiB
Groff
64 lines
1.7 KiB
Groff
.TH RDJPGCOM 1 "02 April 2009"
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.SH NAME
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rdjpgcom \- display text comments from a JPEG file
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.SH SYNOPSIS
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.B rdjpgcom
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[
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.B \-raw
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]
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[
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.B \-verbose
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]
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[
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.I filename
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]
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.LP
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.SH DESCRIPTION
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.LP
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.B rdjpgcom
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reads the named JPEG/JFIF file, or the standard input if no file is named,
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and prints any text comments found in the file on the standard output.
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.PP
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The JPEG standard allows "comment" (COM) blocks to occur within a JPEG file.
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Although the standard doesn't actually define what COM blocks are for, they
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are widely used to hold user-supplied text strings. This lets you add
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annotations, titles, index terms, etc to your JPEG files, and later retrieve
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them as text. COM blocks do not interfere with the image stored in the JPEG
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file. The maximum size of a COM block is 64K, but you can have as many of
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them as you like in one JPEG file.
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.SH OPTIONS
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.TP
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.B \-raw
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Normally
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.B rdjpgcom
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escapes non-printable characters in comments, for security reasons.
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This option avoids that.
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.PP
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.B \-verbose
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Causes
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.B rdjpgcom
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to also display the JPEG image dimensions.
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.PP
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Switch names may be abbreviated, and are not case sensitive.
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.SH HINTS
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.B rdjpgcom
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does not depend on the IJG JPEG library. Its source code is intended as an
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illustration of the minimum amount of code required to parse a JPEG file
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header correctly.
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.PP
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In
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.B \-verbose
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mode,
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.B rdjpgcom
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will also attempt to print the contents of any "APP12" markers as text.
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Some digital cameras produce APP12 markers containing useful textual
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information. If you like, you can modify the source code to print
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other APPn marker types as well.
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.SH SEE ALSO
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.BR cjpeg (1),
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.BR djpeg (1),
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.BR jpegtran (1),
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.BR wrjpgcom (1)
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.SH AUTHOR
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Independent JPEG Group
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