Unless something comes up, I’m done with the color space conversion accuracy work. I’ll use this post to summarize what I’ve found over the last couple of weeks and link to the posts with the details. The first conclusion is that, using 16-bit precision, for all colors within the gamut of both the source and… [Read More]
Archives for October 2014
On dynamic range — a guest post
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]