If I do not filter through an ICC profile, is CMYK to RGB conversion 1:1? Looks like it when using color pickers like this one.
Asked
Active
Viewed 812 times
0
-
1The question [Are RGB numeric values equal to CMYK percentages?](http://photo.stackexchange.com/q/5022) might also be interesting. – Matthias Dec 11 '12 at 19:41
-
That color picker produces different results from Photoshop color picker. Photoshop color picker returns same CMYK for certain RGB combinations (e.g. colors near bright red edge). – Salman A Dec 11 '12 at 19:55
2 Answers
3
No, it is not. CMYK and RGB have a lot of colors in common, but not all. Both contain colors the other does not.
Illustrative chart: http://static.photo.net/attachments/bboard/00Q/00QOnx-61877884.jpg
Alex
- 1,077
- 6
- 7
-
Very helpful chart, thx. However is it not true that you can map the values from one space to the other (using a naive algorithm like the one in the link above)... they are just out of cmyk bounds sometimes/oftentimes. – jedierikb Dec 11 '12 at 19:39
-
Sure there are conversion algorithms that would find a closest match. If you're wondering if there's a matching pair of algorithms that allows one to convert back and forth between RGB and CMYK without losing data... I'd guess no but I'm not sure about that at all. – Alex Dec 11 '12 at 19:45
-
Just wanted to clarify (for myself) that implementations like this one: http://www.webtoolkit.info/javascript-color-conversion.html can, while making very little sense, produce 1:1 mappings. E.g. ColorConverter.toRGB( ColorConverter.toCMYK( new RGB(0,255,255) ) ); returns the selfsame values as the RGB param. – jedierikb Dec 11 '12 at 20:03
-
0
I found the theoretical answer here helpful:
From a theoretical viewpoint, there's no question that conversion from RGB to CMYK can be completely lossless, so (for example) you can do a round-trip conversion (RGB to CMYk, then back to RGB) and guarantee that the result is identical to the original input.
