Quote:
Originally Posted by colours
It's vaguely ironic to see feisty2 post about "mathematical precision" and using Dither tools to illustrate that, when Dither tools has off-by-one errors scattered throughout the full-range colour conversion functions.
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there's no such thing as infinite precision for computers, I don't see any other better option to do it, anyways, I'll explain what I was saying with the following
Quote:
Originally Posted by colours
Also, good job missing vivan's point. How surprising it is that you find the argument "pointless" when you just ignore what everyone else says.
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I get that stuff vivan or you stated
suppose:
1. there was infinite precision for computers
2. all rgb-yuv444-rgb stuff was done correctly under infinite precision
3. the input value was 0.123
the output value of both "ycgco" and "ycbcr" should be 0.123000000... or 0.1229999999... both are mathematically equal to 0.123, the input value
perfect, end of the story
now the reality is, there's no infinite precision, only higher but still finite precision
say, the higher precision here is "6 significant figures"
the output of ycgco would be like, 0.123000, still mathematically equals to 0.123, cuz there're only things like /2 and /4 inside ycgco stuff, and they won't produce infinite decimals long as the input is not infinite precision
the ycbcr output might be like 0.123456, which != 0.123, cuz obviously ycbcr requires infinite precision for intermediate values to stay the zero error status, some intermediate value gets truncated to 6 significant figures and that leads to the error presented in the output value
the disagreement starts right from here
you and vivan think 0.123456 will become 0.123 if rounded down to 3-significant-figure precision and will =0.123 again so it's lossless
and I think it's cheating, the mathematically lossless method should have an output like ycgco, lossless without rounding