|Re: [hatari-devel] [patch] AVI recording PNG compression level|
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Le 09/11/2014 22:05, Eero Tamminen a écrit :
On sunnuntai 09 marraskuu 2014, Troed Sångberg wrote:
JPG should only be used for photos with "natural content"
PNG should be used for clipart, computer graphics etc
(The algorithms used by JPG assumes things about the content in the same
way as MP3 assumes things about the nature of sound & ears)
Sure, but you can disable the lossy part and still get
some compression from cosine transformation & LZ.
removing the quantization part and only keeping the DCT + RLE will IMO
give poor results when not applied to rather "high" resolution images
(ie : not 320x200 or 640x400) and/or photographic images.
For emulator like images, where you often have strong transitions
between color from one pixel to another, you will most likely get rather
"blocky" results when you use lossy compression, and not very good
compression ratio if you go lossless, as jpeg is more appropriate to
region of pixels with transition between colors (hence the DCT usage)
than to planar graphics where pixels have sometimes no relation to each
other (especially on older machine like ST where you only add 7 level of
intensity per color)