Looking to check on some capabilities of Data.Colour
I was wondering if Data.Colour supported Double-valued colour components > 1.0 or less than 0. I'm looking to create an HDR image processing library, and Haskell has one of the most extensive and correct colour models around, thanks to Russell. With 16bpcc or 32bpcc images, however, I need to be sure to be able to correctly calculate colour values that fall outside the usual [0.0,1.0] gamut. Does Data.Colour support this functionality? -- Jeff
On Thu, 6 Aug 2009, Jeff Heard wrote:
I was wondering if Data.Colour supported Double-valued colour components > 1.0 or less than 0. I'm looking to create an HDR image processing library, and Haskell has one of the most extensive and correct colour models around, thanks to Russell. With 16bpcc or 32bpcc images, however, I need to be sure to be able to correctly calculate colour values that fall outside the usual [0.0,1.0] gamut. Does Data.Colour support this functionality?
Data.Colour supports values outside the range [0,1] for most computations. Components are clamped when extracting to Bounded component types such as Word8 (see toSRGBBounded). There may also some issues with negaive values when converting to non-linear coordinate systems via a transfer function. This is an area I haven't thought to much about, so there could be a few "bugs" lurking here. If found they should be fixed, assuming "right" behaviour can be found.
-- Jeff _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
-- Russell O'Connor http://r6.ca/ ``All talk about `theft,''' the general counsel of the American Graphophone Company wrote, ``is the merest claptrap, for there exists no property in ideas musical, literary or artistic, except as defined by statute.''
On Thu, 6 Aug 2009, roconnor@theorem.ca wrote:
On Thu, 6 Aug 2009, Jeff Heard wrote:
I was wondering if Data.Colour supported Double-valued colour components > 1.0 or less than 0. I'm looking to create an HDR image processing library, and Haskell has one of the most extensive and correct colour models around, thanks to Russell. With 16bpcc or 32bpcc images, however, I need to be sure to be able to correctly calculate colour values that fall outside the usual [0.0,1.0] gamut. Does Data.Colour support this functionality?
Data.Colour supports values outside the range [0,1] for most computations.
To be slightly more techinical, I want add that Data.Colour.Colour is abstract and its interface cares nothing about [0,1]. Gammut issue only arise when converting the abstract data type to and from concrete coordinates, and which colours are outside [0,1]*[0,1]*[0,1] is coorinate system dependent. Since Data.Colour.Colour is abstract and coordinate system indepenent, it cannot (or at least should not) care about such issues for oprations that deal only with abstract colours (operations such as blending, etc.)
Components are clamped when extracting to Bounded component types such as Word8 (see toSRGBBounded). There may also some issues with negaive values when converting to non-linear coordinate systems via a transfer function. This is an area I haven't thought to much about, so there could be a few "bugs" lurking here. If found they should be fixed, assuming "right" behaviour can be found.
-- Jeff _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
-- Russell O'Connor http://r6.ca/ ``All talk about `theft,''' the general counsel of the American Graphophone Company wrote, ``is the merest claptrap, for there exists no property in ideas musical, literary or artistic, except as defined by statute.''
Excellent. That's what I wanted to know :-)
On Thu, Aug 6, 2009 at 4:01 PM,
On Thu, 6 Aug 2009, roconnor@theorem.ca wrote:
On Thu, 6 Aug 2009, Jeff Heard wrote:
I was wondering if Data.Colour supported Double-valued colour components > 1.0 or less than 0. I'm looking to create an HDR image processing library, and Haskell has one of the most extensive and correct colour models around, thanks to Russell. With 16bpcc or 32bpcc images, however, I need to be sure to be able to correctly calculate colour values that fall outside the usual [0.0,1.0] gamut. Does Data.Colour support this functionality?
Data.Colour supports values outside the range [0,1] for most computations.
To be slightly more techinical, I want add that Data.Colour.Colour is abstract and its interface cares nothing about [0,1]. Gammut issue only arise when converting the abstract data type to and from concrete coordinates, and which colours are outside [0,1]*[0,1]*[0,1] is coorinate system dependent. Since Data.Colour.Colour is abstract and coordinate system indepenent, it cannot (or at least should not) care about such issues for oprations that deal only with abstract colours (operations such as blending, etc.)
Components are clamped when extracting to Bounded component types such as Word8 (see toSRGBBounded). There may also some issues with negaive values when converting to non-linear coordinate systems via a transfer function. This is an area I haven't thought to much about, so there could be a few "bugs" lurking here. If found they should be fixed, assuming "right" behaviour can be found.
-- Jeff _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
-- Russell O'Connor http://r6.ca/ ``All talk about `theft,''' the general counsel of the American Graphophone Company wrote, ``is the merest claptrap, for there exists no property in ideas musical, literary or artistic, except as defined by statute.''
participants (2)
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Jeff Heard -
roconnor＠theorem.ca