Re: image appears to darken when converting RGB->CMYK in Photoshop
Re: image appears to darken when converting RGB->CMYK in Photoshop
- Subject: Re: image appears to darken when converting RGB->CMYK in Photoshop
- From: Lars Borg <email@hidden>
- Date: Fri, 21 Dec 2007 12:53:17 -0800
Matthew,
The image is being converted to the display with BPC. As you
disabled BPC in the conversion there is now no symmetry
(rgb-cmyk-rgb), so the image appears darker.
You can see this using the custom proofing dialog:
Create an RGB black to white gradient.
Select View > Proof Setup > Working CMYK
Select View > Proof Setup > Custom
Turn off/on BPC
Turn on/off Simulate Black ink (on = same as BPC off to screen)
Turn off/on Preview
So which 3/4-tone is lighter?
BPC on, Simulate Black ink off
BPC off, Simulate Black ink on
Lars
I am puzzled by a strange phenomenon in Photoshop.
I take an RGB image, and convert to a CMYK output profile, using Rel
Col intent *without* black point compensation.
The image, on screen, appears to darken substantially. Most of the
image is in-gamut for the destination profile. Checking the L*
values of different areas of the image before and after the
conversion using the eye dropper tool shows that the L* values are
the same - which is what I would expect provided the colour is
in-gamut for the output device. But, on screen it looks darker than
the RGB version.
Granted I am not using the current version of Photoshop, perhaps
this is a bug since squashed. But has anyone else seen this? Is
there a reason this should be so?
Matthew Larmour
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