Samuel,
I've setup my little workplace as close as possible to some standard I
don't recall the number off but when I think of it all of this is futile
as very few real world situation comes close to this standard.
My image are 99.99% raw files from a D610 and if needed I always convert
them to tiff 16 bits + ProPhoto RGB and for internet and only on final
image I use jpeg and sRGB.
10 bit LCD monitor + 10 bit video card + wide gamut monitor calibrated
D65 + Gamma 2.2 + Brightness of 80 cd/m2 ambient at +- 5000k and 50 lux.
Characterization done with DisplayCal + I1 Display Pro 2 or I1 Studio
Print viewing, 5000k Nominal CRI > 80 , 500-2000 lux.
Work done mostly in LR and PS and soft proofing in PS using generic
profile from paper manufacturer at this time. I intent to create my own
in the near future.
I'm printing on a Canon PRO-1000 with Lucia pigment inks, I always use
the 16 bit driver and more and more I prefer using relatively wide gamut
smooth and textured museum grade matte papers but of course I also print
on more glossy paper sometimes but I try to stay away from papers with
OBA. I call them my blue papers.
Below you mention this "Is the profile for output properly constructed?"
I don't know since I haven't build one myself yet. Argylllcms does
recommend a fairly large number of patches to make a profile and the I1
Studio software is doing this with a fraction of this, max 2 sheet of
8.5" x 11". Obviously the results must differ but until I try I wont know.
I made a print (Red River Palo Duro Etching) the other day of a very
colorful image and I'm pretty satisfied of the result but the contrast
could still be improved a little I guess, PS gamut warning showed very
little out of gamut colors but this morning I use ColorThink to show off
the same image and paper combination and the result greatly differ, much
more out of gamut colors. I don't know which to trust now. It could
explain why my prints don't look much like the PS softproof version.
This image protrude mainly above and below the paper gamut, changing
saturation would be useless, no out of gamut color in the a or b
direction , the only change that would work is a change in L*.
This is one off me biggest concern, who and which software can I trust
to do the work properly. I already know PS does many thing in our backs
that are questionable, others that are inaccurate, etc. So I would be
surprised if I shouldn't trust some or all their color handling stuff as
well.
Until I workout for myself a pretty good workflow to realize a pretty
good screen matching print consistently, something like you said above.
I'll do both a soft proof and small hard proof(s) until I get it right.
Some suggestions to get me on the right track as soon as possible?
Thanks,
Yves
On 11/26/2019 8:54 AM, Samuel Chia wrote:
Hi Yves,
I'm glad you enjoyed the lengthy treatise about gamut mapping. Yes, unfortunately, we still do not have a proper solution to this problem after all this time. Beautiful, top-notch gamut mapping is the last great hurdle of digital imaging yet to be breached for the reproduction of general photographs of fine quality. Many still don't understand just how important this is for the visual quality of their prints so it is rarely discussed, understood, and thus there is little pressure on profiling software makers to make radical changes to their mapping. A chicken and egg problem. Most folks just prefer to use Relative Colorimetric with BPC, without even questioning why the out of gamut colours map the way they do. Let alone (what everyone calls) the mystery meat - Perceptual.
If you are printing images that are within the gamut of your output medium but you are getting unpredictable results with significant loss of contrast, something is wrong with your workflow. Too dark output could be many things. Is your print viewing light bright enough? Is your monitor too bright relative to your print viewing environment? Do you use a surround of white pixels at least an inch all around for your image on the monitor? Is the profile for output properly constructed? Are all the printer settings correct for the chosen paper? Etc. Etc. It would be difficult to give more specific advice without knowing more details about your situation.
I'm finding I enjoy printing on smooth matte fine art papers a lot more than glossy baryta papers these days. The measured Dmax and gamut difference is significant, and without proper luminance-preserving gamut mapping I couldn't love the medium as much. In real-world situations, glossy media always, I mean always, has some degree of glare which reduces its contrast and gamut. If it catches a reflection, it can reduce the viewer's ability to see the printed image almost entirely, and suddenly we are faced with the reality that matte media, on the contrary, can have significantly better contrast and gamut in the real world. Modern pigment inksets are finally beginning to give us just barely enough Dmax to make matte prints sing when you want punchy blacks, though the Lucia inks are still somewhat lacking in that regard. Overall gamut is pretty good if one does not over-saturate their images, though by then, even glossy media may not look good enough compared to the eye-popping colours on OLED displays.
Regards,
Samuel
On Tue, 26 Nov 2019 at 20:08, Yves Gauvreau <gauvreau-yves@xxxxxxxxxxx <mailto:gauvreau-yves@xxxxxxxxxxx>> wrote:
Samuel,
I find your "Full story" most interesting (sorry I'm not good with
words, I think your paper deserve more but, I don't know...) and
from below I see the problem isn't fully resolve yet, that is, if
I understand correctly.
As you said yourself,
"The ideal result is one that comes visually closest to the
original image, what we saw after spending many hours editing the image on
our monitors to exactly what we like"
I would believe most if not all people would agree with you and
this goal, especially in the case of "photographic" image. Beside
trying to find a paper that as enough gamut to include our image
colors or trying to eliminate out of gamut colors from our image
for this or that paper, still, such images (no oog), very often,
don't print as the soft proof image looks like and don't look like
the original either, lack of contrast flat looking, to dark, etc.
What would you suggest we do to get as close to this goal as
possible most if not all the time?
Thanks,
Yves
On 11/25/2019 5:27 PM, Samuel Chia wrote:
Hello Yves and all interested in this topic,
The mapping for Colorimetric is well-defined for in-gamut
colours, while there is no so-called proper way to map out of
gamut colours, and that is where different profiling software can
still give different Colorimetric table results. Usually, they
forgo way too much lightness to preserve some saturation, in an
attempt to make the shortest path into the output gamut.
For Perceptual, we have been misled to believe that the only
possible mapping is a non-linear compression type, and so the
mapping is "unpredictable" and thus completely different secret
recipes from one software to the next. In fact, there is nothing
preventing the Perceptual intent from being treated the same way
as Colorimetric for in-gamut colours, and when we open ourselves
to this way of thinking, we can consider something else that is
much more important.
I would like to correct the concept that the shortest movement in
3D space is necessarily the best conversion when it comes to
regular photographs. As Florian has pointed out, lightness shifts
are most noticeable while chroma shifts are the least.
When many people do gamut mapping comparisons, they like to use
synthetic gradients to evaluate the mapping of profiles for both
Colorimeteric and Perceptual tables, which gives a completely
false impression of how well they work for ordinary photographs,
which normally vary significantly in hue and lightness in a small
region, not smoothly graduating from one tone to another, one
colour to another, and usually only have small regions of out of
gamut colours. Thus, lightness-preserving gamut mapping is
significantly better at maintaining the appearance of the
original image, especially when out of gamut colours are
concerned, to avoid loss of detail due to excessive contrast
reduction. I've explained this to some length previously in
an earlier email to the list, here is the link to that.
Lightness-preserving gamut mapping is the key to getting
successful optimal results on relatively low contrast matte media
as opposed to glossy media, however, despite my many attempts at
encouragement to Graeme to implement this properly, including
paying him an hourly fee and travelling to Australia to work with
him full time to get this correct and eliminate communication
misunderstandings over email, I have not been successful at
convincing him. Graeme did implement a luminance-preserving gamut
mapping function for Colprof, however, it is not working as well
as it should. Despite mathematically being a 100% luminance
preserving operation according to the code, it operates in CIECAM
space, and some additional movements are happening, such as the
Helmholtz-Kohlrosch compensation, which is still way too strong
and still resulting in significant contrast loss with out of
gamut colours of dark colours
Full story here:
https://www.freelists.org/post/argyllcms/Reddish-cast-in-shadows-for-Perceptual-rendering-intent-and-commentary-on-gamut-mapping
Allow me to provide two visual examples. These are for printing
on HP Indigo on coated media, which has a gamut virtually exactly
the same as Fogra39, so let's compare to the way the Fogra39
profile is doing gamut mapping in Relative Colorimetric with BPC
to Argyll's Lightness-Preserving mapping, which works well here
because the out of gamut colours are light colours rather than
dark colours. The sunrise hues are out of gamut and you will see
the textural differences preserved much better with
luminance-preserving gamut mapping than with Fogra39, which is
preserving more saturation (and thus shorter movement in 3D
space) but looks worse:
https://www.dropbox.com/s/qaj99v3o234giva/Luminance-preserving-example-1.jpg?dl=0
In this second example, the sky and clouds in the top right
corner are out of gamut in the output media, and need to be
mapped into printer space. Normal gamut mapping sacrifices some
luminance contrast (not all of it of course, that would be
terrible and no software does this), to the point where the
clouds have lost definition against the sky. Argyll's luminance
mapping is preserving this contrast difference, despite the much
greater saturation loss. However, if you look only at the
rightmost image, you would still consider it to look fine despite
the saturation decrease, while in the middle image, you would not
even know that clouds were were defined in the upper right sky in
the original:
https://www.dropbox.com/s/jixuv0x12770btq/Luminance-preserving-example-2.jpg?dl=0
Best regards,
Samuel
On Tue, 26 Nov 2019 at 05:58, Yves Gauvreau
<gauvreau-yves@xxxxxxxxxxx <mailto:gauvreau-yves@xxxxxxxxxxx>> wrote:
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
<mailto: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
<mailto:argyllcms-bounce@xxxxxxxxxxxxx>
<argyllcms-bounce@xxxxxxxxxxxxx
<mailto:argyllcms-bounce@xxxxxxxxxxxxx>> On
> Behalf Of Yves Gauvreau
> Sent: Monday, November 25, 2019 11:50 AM
> To: argyllcms@xxxxxxxxxxxxx <mailto: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
<mailto:graxx@xxxxxxxxxxxx> wrote:
>> Yves,
>>
>> How does Argyll do Perceptual Intent?
>> I have not read anything about that. It's probably in Argyll
> documentation?
>> But, in general, it's a matter of decreasing saturation to
move the out of
> gamut 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 between
> their Perceptual and Colorimetric intents -- to make their
lives easier and
> to avoid users calling them on the telephone to complain
about the
> "difference".
>> / Roger
>>
>> -----Original Message-----
>> From: argyllcms-bounce@xxxxxxxxxxxxx
<mailto:argyllcms-bounce@xxxxxxxxxxxxx>
<argyllcms-bounce@xxxxxxxxxxxxx
<mailto:argyllcms-bounce@xxxxxxxxxxxxx>>
>> On Behalf Of Yves Gauvreau
>> Sent: Monday, November 25, 2019 9:17 AM
>> To: argyllcms@xxxxxxxxxxxxx <mailto:argyllcms@xxxxxxxxxxxxx>
>> Subject: [argyllcms] Re: Rendering intent?
>>
>> Roger,
>>
>> this would mean that "perceptual" as a different meaning
depending on
> which tool you use, right? How Argyllcms does this?
>> Is the same true for Relative colorimetric? Is only a
change in saturation
> considered with the relative intent or something else?
>> My understanding of a color is that it is defined by a
point in some 3
> dimensional 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.
>>
>> On 11/25/2019 8:23 AM, graxx@xxxxxxxxxxxx
<mailto: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
<mailto:argyllcms-bounce@xxxxxxxxxxxxx>
<argyllcms-bounce@xxxxxxxxxxxxx
<mailto:argyllcms-bounce@xxxxxxxxxxxxx>>
>>> On Behalf Of Yves Gauvreau
>>> Sent: Monday, November 25, 2019 8:21 AM
>>> To: argyllcms@xxxxxxxxxxxxx <mailto: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
> this.
>>> Thanks,
>>> Yves
>>>
>>>
>>>
>>>
>>>
>>
>
>
