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diff --git a/converter/other/pnmtopng.README b/converter/other/pnmtopng.README new file mode 100644 index 00000000..bfa524dc --- /dev/null +++ b/converter/other/pnmtopng.README @@ -0,0 +1,101 @@ +Pnmtopng and Pngtopnm are based on programs of the same name in the +Pnmtopng package owned by Alexander Lehmann and Willem Van Schaik, +available at http://www.libpng.org/pub/png/src on 2001.07.14. + +I added it to and adapted it to Netpbm on 2000.03.02 to make it more +easily available to people. I applied a patch on 2000.06.03 to bring +it up the 2.37.4 release of that package. I updated it again on +2001.07.14 to bring it up to Release 2.37.5. There is no process in +place to bring improvements to the base package into the Netpbm +version, but there hasn't been a lot of update activity anyway. + +Attached below is the file README from Release 2.37.5 of the base +package. + +Here are the differences between the base and the Netpbm version: + + I added an "unsigned" to make formal and actual arguments to png_sig_cmp() + match and quiet a compiler warning. + + I fixed an "include" statement so the dependencies work out right. + + I removed the BIGGRAYS stuff, which became obsolete in Netpbm 9.0 + + I replaced a PPM_MAXVAL with PPM_OVERALLMAXAL to handle the new 16 bits + formats. + + macro VERSION is defined directly in pngtopnm.c and pnmtopng.c instead + of being included via file version.h. + + Pnmtopng, since June 2001, reads one row at a time instead of holding + the entire image in memory. That makes it work with large bitmaps + where it would otherwise run out of memory. It also works faster with + bitmaps since a bit takes up only a bit of memory in a cached input + file, but 96 bits of memory after reading it into a Netpbm data + structure. + + The base Pnmtopng ignores -transparent if it specifies a color that + isn't in the image. Netpbm's Pnmtopng selects a nearby color that _is_ + in the image, which is what base Pnmtopng did before October 2000. + Netpbm's Pnmtopng lets you put an '=' sign before the color to specify + that you don't want a nearby color to be chosen, i.e. you want the + base Pnmtopng function. This is consistent with Pnmtogif. + +There were some other changes necessary before Netpbm 9.0, but the change +of the xelval type from 1 byte to 4 made them unnecessary. + + +** PNMTOPNG / PNGTOPNM +** version 2.37.5 - 24 October 2000 + +[This is a semi-official bug-fix and enhancement release; I sort of took over + maintenance of this package while Willem was on an extended bike trip, and + for now I'm continuing with periodic, small updates. Version 2.37 (March + 1998) was never publicly released, partly because Willem had hoped to quiet + gcc's "<var> might be clobbered by `longjmp'" warnings. Those are fixed in + 2.37.2; under Solaris, they resulted in stack corruption even when there was + no error in the image files or libraries. Version 2.37.3 fixes a minor bug + w.r.t. error exits and generally does cleaner error exits (close files, etc.) + Version 2.37.4 fixes a bug that caused 16-shade grayscale images to be written + as 8-bit grayscale instead of (smaller) 4-bit colormapped images (bug report, + analysis and fix by Rafal Rzeczkowski), and it supports the new/upcoming + pbmplus release. Version 2.37.5 fixes a bug in -transparent handling (pnmtopng + no longer chooses an approximate color if the specified one isn't present) and + quiets a gcc warning in the non-16-bit version. + --Greg Roelofs] + +The utilities pnmtopng and pngtopnm are based on other pbm tools and require +the libraries included in the pbmplus/netpbm package. Also required are the +png library and the zlib compression library. + +These can be found at: + ftp://swrinde.nde.swri.edu/pub/png/src/libpng-* + ftp://swrinde.nde.swri.edu/pub/png/src/zlib-* + ftp://ftp.x.org/contrib/utilities/netpbm-1mar1994* +or see + http://www.libpng.org/pub/png/apps/pnmtopng.html + http://netpbm.sourceforge.net/ + http://www.acme.com/software/pbmplus/ [update coming soon?] + +To compile and install a makefile is provided. Do check the directories +where you have put the required libraries. Then either accommodate the +makefile or make links from generic names (e.g., zlib) to version-specific +directories (e.g., zlib-1.1.3), which is the recommended way. + +For testing purposes, have a look at the test-set PngSuite.tar.gz, which +contains a small test-image for every PNG color type and for most PNG chunk +types. It can be found at: + http://www.schaik.com/pngsuite/pngsuite.html + ftp://swrinde.nde.swri.edu/pub/png/images/suite/ + +Other web pages with PNG images are at: + http://www.libpng.org/pub/png/png-textures.html + http://www.libpng.org/pub/png/pngs-img.html + http://www.libpng.org/pub/png/pngpic2.html + http://www.libpng.org/pub/png/colorcube/ + http://www.libpng.org/pub/png/pngmisc.html#images + +------ +Alexander Lehmann <lehmann@usa.net> +Willem van Schaik <willem@schaik.com> +Greg Roelofs <newt@pobox.com> |