[Webkit-unassigned] [Bug 62905] New: Canvas rendering should be done in linear color space (gamma 1) and the result displayed in sRGB color space (approximately gamma 2.2)

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=62905

           Summary: Canvas rendering should be done in linear color space
                    (gamma 1) and the result displayed in sRGB color space
                    (approximately gamma 2.2)
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: All
        OS/Version: All
            Status: UNCONFIRMED
          Severity: Normal
          Priority: P2
         Component: Canvas
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: webkit at hugues.info
                CC: mdelaney at apple.com


For the moment, it seems that drawing on canvas is done without accounting for gamma, actually making wrong assumptions, like a^x + b^x = (a + b)^x. This gives incorrect results, although they are not always obvious to perceive. For example, all shapes and font antialiasing is incorrect, as are gradients. I propose to address this issue by ensuring that all drawing operations are done in linear space.

I wrote a thorough explanation in a W3C bug report, so please see http://www.w3.org/Bugs/Public/show_bug.cgi?id=12444 for more information. As a picture is often more expressive than text, please take a look at the example picture (also attached here): http://www.w3.org/Bugs/Public/attachment.cgi?id=975 (has to be displayed unscaled).

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