Today we have a guest poster, Jack Hogan. Over on the DPR forum, a question has been asked, and argued endlessly: when faced with a 16-stop intra-scene dynamic range, what’s the dynamic range of an image captured with a 14-bit camera? Jack responded with a little Chautauqua on how a camera works that I thought… [Read More]
ICM vs ACE
In Photoshop, as installed under Windows, You can choose between Adobe’s ACE color engine, and Microsoft’s ICM when performing color space conversions. I have been using ACE up to now. I wondered if ICM could produce more accurate results. In a word, no. I took the 256 million color sRGB noise image that I’d created… [Read More]
Comparing Photoshop and algorithmic color space conversion errors
I took my 256 megapixel image that’s been filled with random 16-bit entries with uniform probability density function, brought it into Photoshop, assigned it the sRGB profile, converted it to Adobe (1998) RGB and wrote it out. I went back to the sRGB image, converted it to ProPhoto RGB, and wrote that out. Then I… [Read More]
Chained color space conversion errors with many rgb color spaces
[Note: this post has been extensively rewritten to correct erroneous results that arose from not performing adequate gamut-mapping operations to make sure the test image was representable within the gamut of all the tested working spaces.] I’ve been trying to come up with a really tough test for color space conversion testing, one that, if… [Read More]
Sequential color space conversions at varying precision
I am now spreading my color space net to include a wide variety of possible RGB working color spaces. I picked 13 for testing: IEC 61966-2-1:1999 sRGB Adobe (1998) RGB Beta RGB Bruce RGB CIE RGB ColorMatch RGB Don-4 RGB ECI RGB v2 Joe Holmes’ Ektaspace PS5 PAL/SECAM RGB ProPhoto RGB SMPTE-C RGB Wide Gamut… [Read More]
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