• FRIGN's avatar
    Mandate "ProPhoto RGB" color space for farbfeld and handle ICC profiles · 3bc6c69a
    FRIGN authored
    I've literally been thinking about this for quite a while now. The
    initial motivation behind defaulting to sRGB was the idea that most data
    on the web was in sRGB anyway.
    However, my assumption was weakened in the sense that the development
    is clearly moving towards images with supplied ICC profiles and software
    slowly catching up to handle this. My tests have shown that more and
    more people even do that on the web, even though it's been a "tradition"
    that Photoshop users "Save for Web" and convert the gamut lossy into
    sRGB to bring a consistent color-"experience" even to those clients not
    supporting ICC profiles and which always assume sRGB.
    
    What made this decision so difficult is that converting to "ProPhoto
    RGB" requires some advanced knowledge on this topic, however, I came to
    the conclusion to implement it given the *2ff- and ff2*-tools handle it
    silently and well in the background, and given the little cms library is
    actually quite okay to use.
    When converting from ff to png, a proper "Pro Photo RGB" ICC V4-profile is
    automatically included in the exported png by ff2png. V4 is not as
    widespread as V2, but in the worst case (no V4 support somewhere) the
    colors will just be a little off.
    
    As an added bonus, any input files for png2ff which include ICC profiles
    are also correctly handled and the color space conversions are executed
    as expected.
    
    Accordingly, the FORMAT-specification has been changed. While at it,
    I added the note on alpha-multiplication. Now the format is very exact
    and shouldn't leave any ambiguities.
    
    jpeg supports ICC profiles as well, but I hadn't had the chance to look
    into it (not as trivial as PNG probably, help appreciated :)), so I'm
    always assuming sRGB here.
    
    Rationale
    ---------
    It is not obvious why one would go through the lenghts of supporting
    this big-gamut colorspace and not just stick with sRGB. In 99% of the
    cases, there's no reason to do that, but with even more extreme
    developments in the OLED-sector and other advances display hardware is
    slowly getting more powerful than sRGB, asking for color information
    which is suitable for the task and actually uses the full potential.
    The decision in this regard was not difficult in farbfeld because we
    always use 16-Bit anyway and won't have to fear posterization in a big-
    gamut color-space.
    3bc6c69a
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