Re: CMYK spaces used for document creation
Re: CMYK spaces used for document creation
- Subject: Re: CMYK spaces used for document creation
- From: Chris Murphy <email@hidden>
- Date: Mon, 2 Nov 2009 16:08:39 -0500
On Nov 2, 2009, at 3:44 PM, Martin Orpen wrote:
On 2 Nov 2009, at 19:28, Andrew Rodney wrote:
On Nov 2, 2009, at 12:20 PM, Martin Orpen wrote:
The major difference between the two procedures is that the
superior proof was produced using a device link profile as well as
a different CMM.
And you tested the same device link in CS4?
Don't see the point?
I was using this example to prove that the banding could not be
blamed solely on errors in the profile or problems with the
destination printer.
CS4 users can't create device links so being able to apply them is
of very limited use.
I have tested Photoshop with device links however. I wrote an
AppleScript to create a test chart:
< http://www.idea-digital.com/index.php/code/34-applescript/48-idea16777216
>
And then converted this from one RGB working space to another using
different device links both in and out of Photoshop and then used
another AppleScript to count the number of clipped pixels.
There was more clipping with the Photoshop conversions compared to
those converted using Argyll.
You'll also note that when you convert from a big space like
ProPhoto to a smaller RGB working space that there are real problems
dealing with imaginary colours which Photoshop routinely clips.
Device link conversions will reveal the imaginary ProPhoto blue
primary for what it really is.... black...
Which is another feature of my printed test pages -- the darkest
blues are awful, requiring Perceptual Intent WITH black point
compensation to allow Photoshop to apply a kludge and turn L values
< 1 into something that a human would appreciate as vivid blue.
Umm. If the test is predicated on doing a good job with a synthetic
target in ProPhotoRGB, then all bets are off. That's not what that
space is designed for. There is hardly a correct way of handling the
gamut mapping of imaginary colors. And there is hardly a real world
instance of images being encoded with imaginary colors in the first
place.
Chris Murphy
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