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Old 28th September 2020, 18:53   #3  |  Link
nhw_pulsar
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Join Date: Apr 2017
Posts: 171
Yes, just for the precision, I used in my codec (NHW) for test the YCoCg matrix from the english wikipedia article.

With these matrixes if you input 8-Bit RGB, it will output 8-Bit YCoCg, just the ranges will be Y: [0-255], Co: [-128,127], Cg: [-128,127], so typically you need to add an offset of +128 for Co and Cg, (and then remove it before converting back to RGB)... This would give a classic YCoCg 8-Bit colorspace...

Just as we are talking about YCoCg, how do you estimate it? Its big advantage is that it is very fast (no multiplies), but visually I find that it is not as good as YCbCR/YUV... When I tested it 3-4 years ago in my codec, I made quite extensive tests at -l9 and -l11 compression settings if I remember correctly, and the results were not visually as pleasant as YUV at the same compression ratio.Did you have same experience?

By the way, I read that your AVIF image compressor: CAVIF is great!

Cheers,
Raphael
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