Re: Color Conversions and Dither
Re: Color Conversions and Dither
- Subject: Re: Color Conversions and Dither
- From: Martin Orpen <email@hidden>
- Date: Fri, 16 May 2008 09:22:50 +0100
On 16 May 2008, at 01:07, Graeme Gill wrote:
So I would guess that if your 16 bit images have rather low noise
levels
at the end of your processing chain, and you judiciously introduce
a minimal level of noise by the use of dithering (or even Photoshop
"Add Noise") of a magnitude of about the 8 bit quantizing step size
(e.g.
around 0.5% or so), then the resulting images will be more visually
robust
in the face of any subsequent quantization due to color conversion or
screening.
But isn't the biggest problem with the OP's high-bit workflow the
earlier conversion from 16 bit ProPhoto to 8 bit Adobe RGB?
For example, I would imagine that an RGB image with lots of vivid
blues will get clipped during the RGB to RGB conversion and the
resultant CMYK is going to produce blues that are composed of clogged
C and M with nothing to give detail in the weaker Y and K channels?
Whereas converting ProPhoto directly to CMYK might show less M and
more detail in the weaker Y & K channels shouldn't it?
Dithering seems of little importance compared to the damage that is
done to the image by doing an RGB to RGB conversion prior to sending
it to the printer for a CMYK conversion. Admittedly I'm viewing this
from an Adobe-centric perspective. So, outside of Photoshop is there
software available that allows you to do RGB to RGB conversion *with*
some form of gamut compression?
--
Martin Orpen
Idea Digital Imaging Ltd
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