Archives for 2014

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]

[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]

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]

Now let’s look at ProPhotoRGB conversion errors with 15-bit quantization.  I took all 16+ million colors in sRGB and converted them to PPRGB and back, quantizing to 15-bits per color plane after each conversion. The conversions themselves were performed algorithmically (no tables involved) with double precision floating point, and have errors on the order of… [Read More]

ProPhoto RGB is not recommended as an 8-bit color space, but I thought I’d start there. I took all 16+ million colors in sRGB and converted them to PPRGB and back, quantizing to 8-bits per color plane after each conversion. The conversions themselves were performed algorithmically (no tables involved) with double precision floating point, and… [Read More]