An "enhanced" absolute colorimetric intent?
An "enhanced" absolute colorimetric intent?
- Subject: An "enhanced" absolute colorimetric intent?
- From: Marco Ugolini <email@hidden>
- Date: Mon, 25 Jul 2005 01:23:37 -0700
In a message dated Wed, 20 Jul 2005 11:22:11, Steve Upton wrote:
> At 11:38 AM -0500 7/20/05, Rich Apollo wrote:
>> On Jul 20, 2005, at 10:44 AM, email@hidden wrote:
>>>
>>> From: Steve Upton <email@hidden>
>>>
>>
>>> It is interesting to note that Adobe has made a change in Photoshop CS2 that
>>> is along the same lines. That is, if you choose to convert from a non-D50
>>> space like sRGB to a print space using absolute colorimetric, you no longer
>>> get a blue white point as you did in earlier versions but rather a
>>> D50-source white point that is more in line with what people expect.
>>
>> Is this different than using a relative colorimetric intent?
>
> I'm not sure about that one... I haven't tested it thoroughly yet... Chris
> Murphy may know?
I may have missed any follow-ups on the list regarding this subject, but let
me see if I am getting it correctly.
Let's revisit the ground rules first. By definition, an absolute
colorimetric conversion is meant to transform each color in the source space
into its exact colorimetric equivalent in the target color space, including
the white point. ALL colors, white point included, are translated into their
colorimetrically closest equivalent in the target space. The relative
colorimetric intent, instead, maps the source white into the white of the
target space, then finds the closest colorimetric equivalents for all other
colors while at the same time shifting their brightness to fit the target's
brightness range as determined by its white point.
I hope I got this much right so far.
Now, if this is so, then it would seem to me that the "enhanced" absolute
colorimetric intent mentioned in the quote above is no different from a
relative colorimetric intent pure and simple. If the two end up being the
same, why create this "enhanced AbsCol," and not just use RelCol instead?
And if the AbsCol intent ends up being "enhanced," what do we do when we
need to use it the old-fashioned way, WITHOUT enhancements?
This is rather confusing.
Thank you for any clarifications you may send this way.
--------------
Marco Ugolini
Mill Valley, CA
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