add pngquant 0.95

convert 32-bit RGBA PNGs into 8-bit RGBA-palette PNGs

PR:		34734
Submitted by:	Alex Hayward <xelah@xelah.com>

1 files changed, 40 insertions, 0 deletions

diff --git a/graphics/pngquant/pkg-descr b/graphics/pngquant/pkg-descr
new file mode 100644
index 000000000000..47d9294728a1
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+++ b/graphics/pngquant/pkg-descr
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+pngquant is a simple tool with one purpose:  convert 32-bit RGBA PNGs into
+8-bit RGBA-palette PNGs (or fewer than 8 bits, if you want), via quantization
+and either ordered or diffusion (Floyd-Steinberg) dithering.  The fact that
+you can also use it on RGB or even palette images (e.g., to further color-
+reduce them to 16 colors or whatever) is just a nice little bonus.
+ 
+The current version is fully functional in the sense that it can do:
+ 
+ - nice reduction of all PNG image types to 256-color (or smaller) palette
+ - automatic optimization of tRNS chunks
+ - batch conversion of multiple files (e.g., "pngquant 256 *.png")
+ - Unix-style command-line filtering (e.g., "... | pngquant 16 | ...")
+ 
+...on at least Unix and Win32.  It should be pretty easy to port to almost
+any other platform with a command-line interface and unstructured (stream-
+oriented) files, including VMS but probably not VM or MVS.
+ 
+It does still lack a few features:
+ 
+ - no ancillary chunk preservation (except gAMA)
+ - no preservation of significant-bits info after rescaling (sBIT chunk)
+ - no mapfile support
+ - no "native" handling of 16-bit-per-sample files or gray+alpha files
+    (i.e., all samples are truncated to 8 bits and all images are promoted
+    to RGBA before quantization)
+ 
+These issues will be addressed in a post-1.0 release.
+ 
+By the way, be sure to check "before" and "after" file sizes, preferably with
+pngcrush (http://pmt.sourceforge.net/pngcrush/); dithered palette images may
+be four times smaller to begin with, but they don't compress nearly as well
+as grayscale and truecolor images.  Some images, such as Henri Sivonen's alpha
+button (http://www.pp.htv.fi/hsivone1/css-test/bitmapstyle.html), can be made
+smaller as full 32-bit RGBA images (4076 bytes in this case) than as either
+FS-dithered palette (4550 bytes) or ordered-dither palette (4482 bytes) images.
+ 
+WWW: http://www.libpng.org/pub/png/apps/pngquant.html
+ 
+Greg Roelofs
+newt@pobox.com