- From: Andrew Somers via GitHub <sysbot+gh@w3.org>
- Date: Sat, 18 Sep 2021 02:27:22 +0000
- To: public-css-archive@w3.org
> _I as well am interested to hear about the discrepancy of documented white point vs actual used white point. I am aware that for sRGB that 0.312700, 0.329000 ....SNIP .... the actual values that should be used are 0.31272, 0.32903.._ **"Back in the Olden Days"** (meaning the 1980s/1990s) when computers were 8bit to 16bit, and a floating point coprocessor was not a standard item, these kinds of values were typically rounded to the fourth decimal place. Floating point chips weren't really "standard" in general purpose computers 'til the 1990s with the i486 and later Pentium, and even then..... <img width="532" alt="Screen Shot 2021-09-17 at 7 02 26 PM" src="https://user-images.githubusercontent.com/42009457/133868718-e05d7585-8b1e-4abf-98ae-e2eee0553bbe.png"> ....back then there were plenty of good reasons, performance and otherwise, to round at 3 or 4. Today we're in a more luxurious time as far as processing speed. (Though today there are still issues with base10 floating point math on base2 computers.) Nevertheless, a lot of "standards" prior to year 2000 were rounded at 3 or 4 places, but are being recalculated for our modern times. Is it worth it? the errors are small — but recursion can result in cumulative errors that are not small. In compositing for instance, a modern visual effect can have hundreds of layers, so a ∆E less than 1 can cumulatively become more than 1 fairly quickly. That said, the bigger problem is when an important constant is not _consistent_ across operations. 0.313, 0.329 is probably fine in most cases, **so long as** it is used for all transforms in both directions. But mixing 0.313, 0.329 for transforms in one direction and 0.31272, 0.32903 for the other direction, the errors can add up. There is already a lot of approximation going on regarding digital color on displays ... trying to find the source of some little weird error can be maddening, it'd be good to remove as many error sources as possible..... -- GitHub Notification of comment by Myndex Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/6618#issuecomment-922163891 using your GitHub account -- Sent via github-notify-ml as configured in https://github.com/w3c/github-notify-ml-config
Received on Saturday, 18 September 2021 02:27:23 UTC