Re: alpha blending
James Cloos <[email protected]>
| Newsgroups | gmane.comp.lib.cairo |
|---|---|
| Message-ID | <[email protected]> |
>>>>> "BS" == Bill Spitzak <[email protected]> writes: BS> There are a couple problems: BS> First there is "coverage" values which are calculated by the filling BS> algorithm. These in fact are not gamma corrected, .5 should mean BS> .5. All masks and alpha channels are coverage values In case I wasn't clear, the bug I referenced (and therefor my query here) were only about changing the way A is combined, and leaving the R, G & B as they are. Would that still lead to the issues you noted were the existing OPs changed? That being asked, the bug's proposal, then, is little different than converting everything to linear on input and back to gamma values on output, yes? Except that cairo explicitly does not treat alpha as gamma-corrected because unlike PDF it uses the one value for a combination of coverage and transparancy? Therefore gamma-correcting alpha is contrary to cairo's design? -JimC -- James Cloos <[email protected]> OpenPGP: 0x997A9F17ED7DAEA6 -- cairo mailing list [email protected] http://lists.cairographics.org/mailman/listinfo/cairo