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That's really cool. I didn't realize you could do a lossless 24-bit palette with PNG.
by lancefisher 15y ago
That's really cool. I didn't realize you could do a lossless 24-bit palette with PNG.
- jmaygarden 15y agoA PNG is pretty much a zlib compressed bitmap.
- ars 15y agoThat's not true. PNG has some filters that pre-compress the image before sending it to zlib.
- leek 15y agoI'd say that still falls under the realm of being "pretty much a zlib compressed bitmap", no?
- ars 15y agoNo, I wouldn't say that. Those filters make a huge difference to the compression ratio! The png optimizers you see (optipng, pngcrush, etc)? What they do is carefully pick the optimum filters to get the best file size. So I'd say those filters were the most important part of the compression.
- warfangle 15y agoOne of the few truly interesting articles on Smashing Magazine about optimizing pngs for their filters. It shows that yes, the filters are really a huge part of how pngs get compressed: http://www.smashingmagazine.com/2009/07/15/clever-png-optimization-techniques/ http://www.smashingmagazine.com/2009/07/15/clever-png-optimi...
- jmaygarden 15y agoYou are correct. I almost qualified the statement as such, but figured "pretty much" was good enough to get my point across in a hurry. My point being that zlib compressed 24-bit RGB values in a PNG is normal. It's a different approach than lossy DCT quantization used in JPEG.