Luminous Landscape Forum

Raw & Post Processing, Printing => Colour Management => Topic started by: NAwlins_Contrarian on September 18, 2019, 09:25:29 pm

Title: Color space matter for B&W image?
Post by: NAwlins_Contrarian on September 18, 2019, 09:25:29 pm
Where the end result of a raw conversion is a black and white image (for every pixel, R=G=B), does it matter what color space the image is exported into? I think stating the same question somewhat differently, among sRGB, Adobe RGB, ProPhoto RGB, and any other common, standard color space, is there any difference among the darkest black and/or the whitest white that can be described?

With all due respect to Nigel Tufnel, I'm asking whether he was correct in saying, "There's something about this that's so black, it's like how much more black could this be? And the answer is none. None more black." (This is Spinal Tap (1984))
Title: Re: Color space matter for B&W image?
Post by: digitaldog on September 18, 2019, 09:31:04 pm
There may be small differences based on the working space gamma encoding.

Title: Re: Color space matter for B&W image?
Post by: Doug Gray on September 18, 2019, 11:12:20 pm
Where the end result of a raw conversion is a black and white image (for every pixel, R=G=B), does it matter what color space the image is exported into? I think stating the same question somewhat differently, among sRGB, Adobe RGB, ProPhoto RGB, and any other common, standard color space, is there any difference among the darkest black and/or the whitest white that can be described?

With all due respect to Nigel Tufnel, I'm asking whether he was correct in saying, "There's something about this that's so black, it's like how much more black could this be? And the answer is none. None more black." (This is Spinal Tap (1984))

As Andrew noted, there are only small differences that are insignificant in a practical sense.

One thing I was somewhat surprised at is that if you run over 8 bit RGB steps from 0 to 255, ProPhoto RGB has an average dE 2000 that is usually lower and has a lower average, than either sRGB or Adobe RGB 1998.

This is the opposite of performance in colors where ProPhoto RGB, Adobe RGB 1998, and sRGB, have larger to smaller deltas. The reason is that all 8 bit colorspaces have 256 steps and it just happens that the ProPhoto RGB gamma of 1.8 has the lowest overall dE2000.

However, all of them have deltaE2000 values well under 1.0 for all the steps so you won't normally see any differences.
Title: Re: Color space matter for B&W image?
Post by: NAwlins_Contrarian on September 20, 2019, 12:47:35 am
Thanks, gentlemen!

Insofar as you tell me that 8-bit sRGB has deltaE2000 values well under 1.0 for all the steps, I will maintain my prior practice of exporting B&W files as sRGB.