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Title: Colour space "width" comparison Post by: PH Focal-Scape on July 12, 2009, 09:42:35 AM Having updated the printer driver for my Canon Pro 9500 I decided to regenerate the custom printer profiles using Profile Prism.
Out of curiosity I decided to compare the 3D visualizations of the PP profile compared to the corresponding Ilford Paper profile (for the specific paper and printer), and also with the nearest Canon generated paper/printer profile. Interestingly the PP colour space "width" is significantly less than the other two, but is smoother (less angular). I wasn't expecting such a "width" difference. Last year when I first generated the particular paper's profile using PP I preferred the PP profile printed output over the equivalent Ilford. I expect that the preference remains. Any comment or explanation would be appreciated. PETER Title: Re: Colour space "width" comparison Post by: admin on July 12, 2009, 01:21:47 PM When you compare, make sure you are comparing the same intent. Perceptual intent, for example, will show an extended gamut. Also, some profiling tools will "bend" the gamuts a little and then compress them into the printer gamut even when using relative colorimetric intent, thereby making the gamut look larger than it really is. Can you post the gamut shots? Might be interesting to look.
Mike Title: Re: Colour space "width" comparison Post by: PH Focal-Scape on July 12, 2009, 08:57:09 PM When you compare, make sure you are comparing the same intent. Perceptual intent, for example, will show an extended gamut. Also, some profiling tools will "bend" the gamuts a little and then compress them into the printer gamut even when using relative colorimetric intent, thereby making the gamut look larger than it really is. Can you post the gamut shots? Might be interesting to look. Mike Thanks Mike. Here's a typical example relating to Ilford Fine Art paper: (http://www.pastoralsystems.co.nz/pshphotos/colourspaces.jpg) The blue outline represents the PP profile and the red, the Ilford version. And an example relating to Ilford Gold Fibre Silk paper: (http://www.pastoralsystems.co.nz/pshphotos/colourspaces2.jpg) The pink outline represents the PP profile and the green, the Ilford version. Does the "icc" versus "icm" make a difference? Incidentally, the PP reports from the scanning of reference and target are very good. PETER Title: Re: Colour gamut (not "space") "width" comparison Post by: PH Focal-Scape on July 16, 2009, 09:47:37 PM As a follow up:
I has compared the gamuts of three Ilford provided specific paper/ink/print profiles with the PP generated equivalents. All three PP profiles are distinctly "inside" their Ilford versions. Merely interesting. Subjectively I think the PP profiled prints are at least as good and mostly better from the point of view of looking more natural/realistic. PETER Title: Re: Colour space "width" comparison Post by: admin on July 16, 2009, 10:13:43 PM Could be just a little bit of "artificial" stretch that is being done by other software to accommodate images with a large gamut. Sounds like cheating but if you know how the innards of profiles and color management models work, it's all a bit arbitrary. The important thing is that in gamut colors are mapped properly so that people don't notice hue shifts or contrast problems. Other than that, as you've seen, two profiles of different sizes can look pretty similar.
Mike |