| 1 | ===========================
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| 2 | PNG: The Definitive Guide
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| 3 | ===========================
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| 4 |
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| 5 | Source Code
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| 6 |
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| 7 | Chapters 13, 14 and 15 of "PNG: The Definitive Guide" discuss three free,
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| 8 | cross-platform demo programs that show how to use the libpng reference
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| 9 | library: rpng, rpng2 and wpng. rpng and rpng2 are viewers; the first is
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| 10 | a very simple example that that shows how a standard file-viewer might use
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| 11 | libpng, while the second is designed to process streaming data and shows
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| 12 | how a web browser might be written. wpng is a simple command-line program
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| 13 | that reads binary PGM and PPM files (the ``raw'' grayscale and RGB subsets
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| 14 | of PBMPLUS/NetPBM) and converts them to PNG.
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| 15 |
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| 16 | The source code for all three demo programs currently compiles under
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| 17 | Unix, OpenVMS, and 32-bit Windows. (Special thanks to Martin Zinser,
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| 18 | [email protected], for making the necessary changes for OpenVMS and for
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| 19 | providing an appropriate build script.) Build instructions can be found
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| 20 | below.
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| 21 |
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| 22 | Files:
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| 23 |
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| 24 | README this file
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| 25 | LICENSE terms of distribution and reuse (BSD-like or GNU GPL)
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| 26 | COPYING GNU General Public License (GPL)
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| 27 |
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| 28 | Makefile.unx Unix makefile
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| 29 | Makefile.w32 Windows (MSVC) makefile
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| 30 | makevms.com OpenVMS build script
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| 31 |
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| 32 | rpng-win.c Windows front end for the basic viewer
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| 33 | rpng-x.c X Window System (Unix, OpenVMS) front end
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| 34 | readpng.c generic back end for the basic viewer
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| 35 | readpng.h header file for the basic viewer
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| 36 |
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| 37 | rpng2-win.c Windows front end for the progressive viewer
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| 38 | rpng2-x.c X front end for the progressive viewer
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| 39 | readpng2.c generic back end for the progressive viewer
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| 40 | readpng2.h header file for the progressive viewer
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| 41 |
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| 42 | wpng.c generic (text) front end for the converter
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| 43 | writepng.c generic back end for the converter
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| 44 | writepng.h header file for the converter
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| 45 |
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| 46 | toucan.png transparent PNG for testing (by Stefan Schneider)
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| 47 |
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| 48 | Note that, although the programs are designed to be functional, their
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| 49 | primary purpose is to illustrate how to use libpng to add PNG support to
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| 50 | other programs. As such, their user interfaces are crude and definitely
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| 51 | are not intended for everyday use.
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| 52 |
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| 53 | Please see http://www.libpng.org/pub/png/pngbook.html for further infor-
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| 54 | mation and links to the latest version of the source code, and Chapters
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| 55 | 13-15 of the book for detailed discussion of the three programs.
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| 56 |
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| 57 | Greg Roelofs
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| 58 | http://pobox.com/~newt/greg_contact.html
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| 59 | 16 March 2008
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| 60 |
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| 61 |
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| 62 | BUILD INSTRUCTIONS
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| 63 |
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| 64 | - Prerequisites (in order of compilation):
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| 65 |
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| 66 | - zlib http://zlib.net/
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| 67 | - libpng http://www.libpng.org/pub/png/libpng.html
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| 68 | - pngbook http://www.libpng.org/pub/png/book/sources.html
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| 69 |
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| 70 | The pngbook demo programs are explicitly designed to demonstrate proper
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| 71 | coding techniques for using the libpng reference library. As a result,
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| 72 | you need to download and build both zlib (on which libpng depends) and
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| 73 | libpng. A common build setup is to place the zlib, libpng and pngbook
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| 74 | subdirectory trees ("folders") in the same parent directory. Then the
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| 75 | libpng build can refer to files in ../zlib (or ..\zlib or [-.zlib]),
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| 76 | and similarly for the pngbook build.
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| 77 |
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| 78 | Note that all three packages are designed to be built from a command
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| 79 | line by default; those who wish to use a graphical or other integrated
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| 80 | development environments are on their own.
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| 81 |
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| 82 |
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| 83 | - Unix:
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| 84 |
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| 85 | Unpack the latest pngbook sources (which should correspond to this
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| 86 | README file) into a directory and change into that directory.
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| 87 |
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| 88 | Copy Makefile.unx to Makefile and edit the PNG* and Z* variables
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| 89 | appropriately (possibly also the X* variables if necessary).
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| 90 |
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| 91 | make
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| 92 |
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| 93 | There is no "install" target, so copy the three executables somewhere
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| 94 | in your path or run them from the current directory. All three will
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| 95 | print a basic usage screen when run without any command-line arguments;
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| 96 | see the book for more details.
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| 97 |
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| 98 |
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| 99 | - Windows:
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| 100 |
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| 101 | Unpack the latest pngbook sources (which should correspond to this
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| 102 | README file) into a folder, open a "DOS shell" or "command prompt"
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| 103 | or equivalent command-line window, and cd into the folder where you
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| 104 | unpacked the source code.
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| 105 |
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| 106 | For MSVC, set up the necessary environment variables by invoking
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| 107 |
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| 108 | %devstudio%\vc\bin\vcvars32.bat
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| 109 |
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| 110 | where where %devstudio% is the installation directory for MSVC /
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| 111 | DevStudio. If you get "environment out of space" errors under 95/98,
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| 112 | create a desktop shortcut with "c:\windows\command.com /e:4096" as
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| 113 | the program command line and set the working directory to the pngbook
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| 114 | directory. Then double-click to open the new DOS-prompt window with
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| 115 | a bigger environment and retry the commands above.
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| 116 |
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| 117 | Copy Makefile.w32 to Makefile and edit the PNGPATH and ZPATH variables
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| 118 | appropriately (possibly also the "INC" and "LIB" variables if needed).
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| 119 | Note that the names of the dynamic and static libpng and zlib libraries
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| 120 | used in the makefile may change in later releases of the libraries.
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| 121 | Also note that, as of libpng version 1.0.5, MSVC DLL builds do not work.
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| 122 | This makefile therefore builds statically linked executables, but if
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| 123 | the DLL problems ever get fixed, uncommenting the appropriate PNGLIB
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| 124 | and ZLIB lines will build dynamically linked executables instead.
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| 125 |
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| 126 | Do the build by typing
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| 127 |
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| 128 | nmake
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| 129 |
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| 130 | The result should be three executables: rpng-win.exe, rpng2-win.exe,
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| 131 | and wpng.exe. Copy them somewhere in your PATH or run them from the
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| 132 | current folder. Like the Unix versions, the two windowed programs
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| 133 | (rpng and rpng2) now display a usage screen in a console window when
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| 134 | invoked without command-line arguments; this is new behavior as of
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| 135 | the June 2001 release. Note that the programs use the Unix-style "-"
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| 136 | character to specify options, instead of the more common DOS/Windows
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| 137 | "/" character. (For example: "rpng2-win -bgpat 4 foo.png", not
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| 138 | "rpng2-win /bgpat 4 foo.png")
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| 139 |
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| 140 |
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| 141 | - OpenVMS:
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| 142 |
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| 143 | Unpack the pngbook sources into a subdirectory and change into that
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| 144 | subdirectory.
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| 145 |
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| 146 | Edit makevms.com appropriately, specifically the zpath and pngpath
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| 147 | variables.
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| 148 |
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| 149 | @makevms
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| 150 |
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| 151 | To run the programs, they probably first need to be set up as "foreign
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| 152 | symbols," with "disk" and "dir" set appropriately:
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| 153 |
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| 154 | $ rpng == "$disk:[dir]rpng-x.exe"
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| 155 | $ rpng2 == "$disk:[dir]rpng2-x.exe"
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| 156 | $ wpng == "$disk:[dir]wpng.exe"
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| 157 |
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| 158 | All three will print a basic usage screen when run without any command-
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| 159 | line arguments; see the book for more details. Note that the options
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| 160 | style is Unix-like, i.e., preceded by "-" rather than "/".
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| 161 |
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| 162 |
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| 163 | RUNNING THE PROGRAMS: (VERY) BRIEF INTRO
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| 164 |
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| 165 | rpng is a simple PNG viewer that can display transparent PNGs with a
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| 166 | specified background color; for example,
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| 167 |
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| 168 | rpng -bgcolor #ff0000 toucan.png
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| 169 |
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| 170 | would display the image with a red background. rpng2 is a progressive
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| 171 | viewer that simulates a web browser in some respects; it can display
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| 172 | images against either a background color or a dynamically generated
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| 173 | background image. For example:
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| 174 |
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| 175 | rpng2 -bgpat 16 toucan.png
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| 176 |
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| 177 | wpng is a purely command-line image converter from binary PBMPLUS/NetPBM
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| 178 | format (.pgm or .ppm) to PNG; for example,
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| 179 |
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| 180 | wpng -time < toucan-notrans.ppm > toucan-notrans.png
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| 181 |
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| 182 | would convert the specified PPM file (using redirection) to PNG, auto-
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| 183 | matically setting the PNG modification-time chunk.
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| 184 |
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| 185 | All options can be abbreviated to the shortest unique value; for example,
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| 186 | "-bgc" for -bgcolor (versus "-bgp" for -bgpat), or "-g" for -gamma.
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