My only "questioning" with using only saturation to bring a color into
the gamut of the destination colorspace is that its a 1d operation and
it may not be the shortest path to the gamut boundary (destination) in
other words, a possibly less obvious conversion may exist. The answers
of Florian suggest other approach would difficult to implement with the
current CLut structure.
Not much to do with the term itself.
Thanks Roger,
Yves
On 11/25/2019 12:15 PM, graxx@xxxxxxxxxxxx wrote:
Yves,
Look into *any* Adobe profiles, they have all three mandated ICC intents.
I can see you don't like the term "Saturation", consider the term "Chroma"
instead.
/ Roger
-----Original Message-----
From: argyllcms-bounce@xxxxxxxxxxxxx <argyllcms-bounce@xxxxxxxxxxxxx> On
Behalf Of Yves Gauvreau
Sent: Monday, November 25, 2019 11:50 AM
To: argyllcms@xxxxxxxxxxxxx
Subject: [argyllcms] Re: Rendering intent?
Roger,
I don't like the idea of just decreasing the saturation at least from a
numerical perspective. From what I've read we are not that good at
discerning colors, it takes serious effort on our part and practically
laboratory conditions to discern colors with less than 2-5 DE?? of
difference. If this is right, just changing saturation would probably not
result in optimal result especially at low L* for example. It maybe a
"shorter" path to increase L* then to vary a* and b* such as to vary only
the saturation. This should be especially true if the shortest path also
provide a less discernible color difference, doesn't it?
As for PS you could be right I don't know but it could be also because the
printer profile doesn't provide the 2 rendering intent tables?
Yves
On 11/25/2019 10:17 AM, graxx@xxxxxxxxxxxx wrote:
Yves,documentation?
How does Argyll do Perceptual Intent?
I have not read anything about that. It's probably in Argyll
But, in general, it's a matter of decreasing saturation to move the out ofgamut colors inside the Destination gamut, presumably preserving the
original hue angle, but there's a whole science in how to do this, and not
all profilers do it the same. Some move greens further in, others move reds
further in and so on. Many will use a decreasing saturation function in
that, only out of gamut colors will be progressively desaturated at the
gamut's edge. Others will apply a wholesale desaturation, decreasing all
Source colors so that they fit inside the Destination gamut. There's a lot
of good papers out there on how this is done. But there's nothing like
finding it out for yourself empirically. It's not hard to analyze but it's
time consuming, without some kinds of analytical tools.
Take Photoshop. Photoshop is easy because there is no difference betweentheir Perceptual and Colorimetric intents -- to make their lives easier and
to avoid users calling them on the telephone to complain about the
"difference".
/ Rogerwhich tool you use, right? How Argyllcms does this?
-----Original Message-----
From: argyllcms-bounce@xxxxxxxxxxxxx <argyllcms-bounce@xxxxxxxxxxxxx>
On Behalf Of Yves Gauvreau
Sent: Monday, November 25, 2019 9:17 AM
To: argyllcms@xxxxxxxxxxxxx
Subject: [argyllcms] Re: Rendering intent?
Roger,
this would mean that "perceptual" as a different meaning depending on
Is the same true for Relative colorimetric? Is only a change in saturationconsidered with the relative intent or something else?
My understanding of a color is that it is defined by a point in some 3dimensional colorspace and if you have to move it around and you limit
yourself to only changing saturation your giving up 2 other potential
options. I would have thought the most recent "distance" metrics or even
the simple euclidean distance to be more appropriate then just shifting the
saturation as seems to be the case in the various docs I've seen. I know I
may not have seen the "right" one. That's why I ask.
this.
On 11/25/2019 8:23 AM, graxx@xxxxxxxxxxxx wrote:
Every profiler I know does the Perceptual intent *differently*.
It's considered their "secret sauce".
/ Roger
-----Original Message-----
From: argyllcms-bounce@xxxxxxxxxxxxx <argyllcms-bounce@xxxxxxxxxxxxx>
On Behalf Of Yves Gauvreau
Sent: Monday, November 25, 2019 8:21 AM
To: argyllcms@xxxxxxxxxxxxx
Subject: [argyllcms] Rendering intent?
Hi,
I'm curious, every time I read some doc on how relative colorimetric
and perceptual intent works, it seems as if it only a saturation (2D)
change is considered, why not the shortest distance (3D) to the gamut
boundary of the destination space?
Can you direct me to something that would explain how Argyllcms does
Thanks,
Yves
