Re: When black is white (or blue is black) was: CMYK spaces used for document creation
Re: When black is white (or blue is black) was: CMYK spaces used for document creation
- Subject: Re: When black is white (or blue is black) was: CMYK spaces used for document creation
- From: Karl Koch <email@hidden>
- Date: Wed, 4 Nov 2009 18:44:19 +0100
Am 04.11.2009 um 18:03 schrieb Martin Orpen:
On 4 Nov 2009, at 15:49, Karl Koch wrote:
now we are getting somewhere and this thread becomes interesting
again.
You show the amount of ignorance that is common with the common user!
I'm glad you appreciate that.
No offense intended!
You could blame Adobe again for not blocking the "perceptual" choice
when no perceptual rendering intent is possible (matrix based
priofile), but that may go too far ;-)
You could also blame yourself for not knowing this fundamental fact –
or just memorize it for future use.
You try to convert from one to the other RGB working space – and
both are matrix based. In a matrix based profile there is only one
way of converting (not quite true, but good enough if we talk Adobe
Photoshop): relaive colorimetric.
You can´t expect to convert out-of-gamut colors this way, so that
they would show detail after conversion.
When building an ICC-DeviceLink profile, you can specify different
renderings, e.g. image based in the case of Argyll. This seems to
be the case in your idiot example. If I do a "normal" perceptual
compression, this is the result:
http://files.me.com/basicc/aec8yi
Yes, it is easy – if you know what you are doing!
Excellent, I thought my version was good -- if I asked the client to
ignore the dark green background...
Your version was ONE way of converting it. When you start from an
extremely wide gamut and convert to an extremely small gamut, you need
to make clear, what your intention is. "Color correct" is just
impossible. So your intention was "max out the contrast while showing
at least some kind of color"
Yours has a nice blue background and green type
Whose "perception" was used to turn R66 G0 B255 to R0 G81 B106?
It´s about as close as "your" background R0 G49 B45 sRGB (converted
from R0 G0 B255 ProPhotoRGB). RGB values without saying which RGB
(profile) mean NOTHING at all, which can be seen clearly in these
examples.
I'm beginning to think that this simple conversion is not as easy as
the colour management consultants led me to believe.
If they did, show them your test image!
You have my permission to use this test image in your future product
releases.
Thanks, we´ll use it for selected customers only ;-)
Best regards,
Karl _______________________________________________
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