kc3-lang/libjpeg-turbo/doc/rdjpgcom.1

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• Hash : e69dd40c
  Author :
  Date : 2024-01-23T13:26:41
  

  Reorganize source to make things easier to find
  
  - 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
  

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• doc/rdjpgcom.1

• .TH RDJPGCOM 1 "02 April 2009"
  .SH NAME
  rdjpgcom \- display text comments from a JPEG file
  .SH SYNOPSIS
  .B rdjpgcom
  [
  .B \-raw
  ]
  [
  .B \-verbose
  ]
  [
  .I filename
  ]
  .LP
  .SH DESCRIPTION
  .LP
  .B rdjpgcom
  reads the named JPEG/JFIF file, or the standard input if no file is named,
  and prints any text comments found in the file on the standard output.
  .PP
  The JPEG standard allows "comment" (COM) blocks to occur within a JPEG file.
  Although the standard doesn't actually define what COM blocks are for, they
  are widely used to hold user-supplied text strings.  This lets you add
  annotations, titles, index terms, etc to your JPEG files, and later retrieve
  them as text.  COM blocks do not interfere with the image stored in the JPEG
  file.  The maximum size of a COM block is 64K, but you can have as many of
  them as you like in one JPEG file.
  .SH OPTIONS
  .TP
  .B \-raw
  Normally
  .B rdjpgcom
  escapes non-printable characters in comments, for security reasons.
  This option avoids that.
  .PP
  .B \-verbose
  Causes
  .B rdjpgcom
  to also display the JPEG image dimensions.
  .PP
  Switch names may be abbreviated, and are not case sensitive.
  .SH HINTS
  .B rdjpgcom
  does not depend on the IJG JPEG library.  Its source code is intended as an
  illustration of the minimum amount of code required to parse a JPEG file
  header correctly.
  .PP
  In
  .B \-verbose
  mode,
  .B rdjpgcom
  will also attempt to print the contents of any "APP12" markers as text.
  Some digital cameras produce APP12 markers containing useful textual
  information.  If you like, you can modify the source code to print
  other APPn marker types as well.
  .SH SEE ALSO
  .BR cjpeg (1),
  .BR djpeg (1),
  .BR jpegtran (1),
  .BR wrjpgcom (1)
  .SH AUTHOR
  Independent JPEG Group
  

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