Colour Management in PL6 - Updated for PL6.3

George · February 15, 2023, 7:50pm

What that profile connection space is is not an item in this discussion. There’s one and PL uses the xyz specs.

Color management is the process of converting colors from one color space to another while preserving the perception. Typically, when displaying an image on your calibrated screen that has been saved in a standard color space such as AdobeRGB, the color management system will convert the colors from AdobeRGB into XYZ (called the “profile connection space”) and then from there to the color space defined by the color profile of your screen.
Since nobody wants to read it I will quote it. This is from DxO.

But the topic at hand is whether there’re 2 conversions when activating soft proof. And there’re. I posted the image from The Manual of Photography several times and nobody reacted on it. As you can see it mentions xyz or lab.

Assigning in a converter is out of the question.

Simulating can’t be anything else is converting.

George

MSmithy · February 15, 2023, 8:10pm

Hmmm. I’m not sure about that. Do you have any official documentation from DXO about this?

George · February 15, 2023, 8:11pm

DON’T YOU READ MY LINK?

George

KeithRJ · February 15, 2023, 10:07pm

I HAVE read that and fully understand it! Ever considered that you don’t understand it @George? The profile connected space is DxO’s working space. Soft proofing is a simulation not a conversation and that is specifically mentioned in DxO’s white paper.

I am sorry @George but I will not be continuing this pointless discussion, especially since you are the only one who has an “issue” with this.

MSmithy · February 15, 2023, 10:35pm

You have a misconception it seem to me. The article says:

"There are also color spaces that are defined independently of any device, such as the XYZ space designed in 1931 by the International Commission on Illumination (abbreviated to CIE from its French name, Commission Internationale de l’Éclairage). This space attempts to model color perception along three axes: X, Y, and Z. "

That is correct. But it does not mean this is what it used for the conversion, because it has shortcomings. If you stop being stubborn and actually pay attention you will notice that the model is from 1931, not exactly the age of digital software.

The concept is correct, but application is not suitable for modern digital world, hence most applications used Lab that is doing the same thing, but it is suitable for needs of modern digital software.

"The Lab color space is itself derived from an earlier reference space, CIE XYZ. In 1931, CIE established a model based on an averaged observers’ visual sensitivity to different wavelengths of light under a specific light source and angle of illumination. From that model, the CIE introduced XYZ tristimulus values and when plotted in 3D form, three coordinates XYZ. In its 2-D form, color is plotted in an elongated n-shaped chart known as the CIE 1931 XY chromaticity diagram.

Lab adopts a 3-D model that uses values that are easier to interpret, with L or Lightness co-ordinate and two a and b color components. The model also closely matches the human color vision, with respect to the perceived differences in color and the distances between them, especially when plotted in a 2-D form using a circular color wheel. However, a Lab coordinate is computed from an XYZ coordinate by “normalizing” to a white-point. This means that under a certain light source, a color that is perceived to have the same color as white is neutral, and will have coordinates, or values, a*=b*=0. In Lab, that light source is D50."

Please don’t be arrogant and think everyone else is stupid. You have fundamental misconceptions and you have been corrected. If you insists on being stubborn about your misconceptions, they will remain firmly your misconceptions.

George · February 16, 2023, 6:44am

A quote from a quote from a link Bold is from me.

But that isn’t my item. My point is that when using the soft proof 2 conversions are done., one from the working color space to the soft proof color space and one from the soft proof color space to the monitors color space. So what you see is an image in the monitors color space with the extra info of what are the oog parts between working color space and soft proof color space.

There’s another consideration for me. Being able to see the true soft proof colors on my screen the rendering intent shouldn’t compress the in-gamut colors.
Now there’re 3 parameters that influence the colors: the rendering intent, the simulate paper&ink and the preserve color details.

George

zkarj · February 16, 2023, 7:17am

The diagram as it now appears is quite understandable to me, where the original wasn’t quite. I still have quibbles with some minor aspects of the language, but I can understand it.

However, in this thread, there has been a fair bit of discussion over “assign” versus “convert” and I think the problem is there need to be THREE terms.

I tried before to describe the problem without referring to images, but text.

First, the data:
Le printemps à Paris

Now we assign the language.
Le printemps à Paris

Oops! That does not make any sense as an English sentence. Let’s try again.

Le printemps à Paris

Now it makes sense, we can do a meaningful conversion.

Springtime in Paris

So, what is the third term? I would call it interpretation.

My analogy doesn’t make this one easy, but imagine someone is speaking the phrase above, whether in the original French or English. It is not understandable to the deaf person.

But behind the speaker of the phrase is a signer who is listening to the phrase, in English or in French, and signing the meaning for the hard of hearing. They are interpreting the phrase in real time but they are not changing the spoken phrase in any way.

I say the monitor profile is never assigned and nor is the image ever converted to the monitor profile. It is only ever interpreted as the monitor profile. Interpretation is technically equivalent to conversion but has no permanence.

George · February 16, 2023, 7:51am

Excact.
But conversion can be done in 2 ways: changing the pixel values in the image permanent or on the fly to the monitor. That last happens. The image itself is untouched. I’m not sure if for soft proofing a copy is made in memory. That’s just a matter how to code it.

George

OXiDant · February 16, 2023, 7:53am

I starting to think can we go back to the day’s we didn’t had any choice?
Just stumbling in the dark.
Export and it didn’t look good on the screen you liked to watch it or the print does look off you just go back adjust a bit and be done with it…

Soft proofing seems to me just a lay over: if the image color footprint doesn’t fit in the chosen “box” you get a warning. It’s too big.
And you decide if you need to adjust the image or get a bigger box.
In order to help out they fitted a “sqeezer” in the box cover so if you proceed the content got sqeezed in the box. They call it “protect saturated colors”.

Ok in reality there are colorspace convertions which have the intent to convert without colorshifts but doesn’t always got it right.
Where i am hoping for is a drivers assist for those who are happy with non calibrated screens and only use softproofing to see if it’s fit in the box of choice.
Due the fact that tools as histogram and clippingwarning and saturation edittools are depending on in which working colorspace you are it’s important that the userinterface is very clear what is effected when changing workingcolorspace.

KeithRJ · February 16, 2023, 7:54am

Interesting analogy.

So to further explain the editing flow we have:

RAW file > Working Colour Space > monitor profile for preview of edits > Export profile

Or

RAW file > Working Colour Space > monitor profile for preview of edits > Optionally: SP preview (simulation within monitor profile) > export profile (from working image and does not have to be the same as SP profile)

Technically:

RAW file > working image (RAM) > Graphic memory for display (including conversion to monitor profile) > export file (from working image)

Or

RAW file > working image (RAM) > Graphic memory for display (including conversion to monitor profile and simulation of SP profile) > export file (from working image)

I believe this matches the diagram and describes what is happening internally in the computer. The blue boxes are either physical files or electronic copies of the image. The two monitors display the image from graphic memory, and the red boxes are the process used to convert from one blue box to another, and finally the green boxes are assigning profiles to the image but not changing any image data.

Additionally, the profile icons are inputs to the assign or the convert processes.

As a final note, and it is important to understand this:

Assign associates a profile with an image but does NOT change the image data in any way but updates the metadata with the assigned profile.

Convert assigns a profile to the image AND changes the image data to match the assigned profile.

A RAW file may have a profile associated with it (if the camera manufacturer supplies one) or you can assign a profile to either match the camera manufacturer’s or another profile to simulate different film etc. An RGB file may have a profile assigned but if it does not you can assign one yourself. When you export a file you choose what profile to convert to which also assigns the profile to the export file.

I hope this helps explains the thought process used to produce this diagram with additional DxO specific algorithms.

KeithRJ · February 16, 2023, 8:04am

Unfortunately many people pestered DxO for ages to add soft proofing. Professionals know what they are doing with colour management so will not have an issue with what DxO has done. It is the hobbyist who is struggling with the concept.

Fortunately I think you can work in PL6 the same as you did with PL5.

In Colour Rendering, find settings that work for your camera and look good for you, then ignore all the monitor warnings, Soft Proofing and SP warnings. Edit away and export and see what the results are like. You do have the Protect Saturated Colours slider (in colour rendering) to help with this process.

This is pretty much what I do except if I see I have very saturated colours I may well decide to check monitor warnings and do a little soft proofing, but this will be for a small proportion of my images.

Two screenshots showing extremes of PSC slider settings.

George · February 16, 2023, 8:28am

It comes close to what I tried to explain you for a long time. Simulation within the monitor profile is the same as converting to the monitor profile.

Assigning is a color profile to an image is the same as setting the dpi values in that image. It’s an info to the screen or printer saying ‘use me as if…’.
Assigning a color profile is only meaningful if that color profile is unknow/missing in the file. By example a jpg with no color profile. Standard sRGB is assigned to that one.

Conversion doesn’t mean that the values of that image are changed. It can be done on the fly too. What happens constant when you look on the monitor.

Read @zkarj post again!!!

George

OXiDant · February 16, 2023, 9:57am

I have the PSC slider on auto. Magic want active.
So when i see that slider rising i know something got squeezed.
Then i can use monitor out of gamut warning to see which parts could be pinched.
And decide to correct manual or let dxo magic do its thing when i export.

The problem for most hobby people is the inconsistency of legacy switch to Wide Gamut.
Often things as golden hour colors get desaturated in the same settings when you switch from legacy to WG in order to gain some control in the darker saturated area’s, which is the “extra part” in the WG working space. The darker saturated bits of your rawfile.
So you raise the colors of the more brighter parts in order to get the same look in your monitor preview.
And when you export to sRGB al that work is squasted and compressed and can give you a nondesired outcome.

I think that’s the biggest problem for all not so into softproofing between colorspaces and profiles.

John-M · February 16, 2023, 10:56am

I reckon that’s a very good/accurate observation, Peter.

Fortunately, PL provides good tools to manage this; Activate Soft Proofing and adjust Preserve Color Detail to taste.

The following tips are “good ones” !

… which can lead to …

John

IanS · February 16, 2023, 11:21am

John, would it be constructive to move the soft proofing feature topic more towards printing for which it is primarily aimed? Most images for the web are in sRGB and when you save a raw image to sRGB, as we have all been doing for years, the default perceptual rendering intent does the job and most people have been fine with the result.

Given that with monitors the result everyone sees depends on their monitor, sRGB, aRGB, P3 etc this makes the discussion difficult.

I think once people start to use soft proofing in the way it was originally intended and everyone can see the results from their own printer, then the knowledge gained can be beneficially fed back into monitor soft proofing.

In an attempt to illustrate what i mean I took Joanne’s famous lobster image (extreme image) and soft proofed against a “plain paper” (extreme paper choice) icc profile I made to maximise the impact. The impact of soft proofing I believe is marked enough to show even with screen grabs of the soft proof:

Original image -no soft proof:

Soft Proof - Perpetual:

Soft Proof - Relative

Soft Proof - Adjusted image to increase contrast etc

Adjusted image with soft proof turned off. garish starting image to get an improvement when printed

I use primarily C1 and one of the biggest drawbacks for me with DXO was the colour management limitations (aRGB) and lack of soft proofing. This is why I have been so happy with DXO now that they use wide gamut and have soft proofing.

I fear that the huge improvement in DXO’s colour processing pipeline is not getting the credit it deserves while the focus is only on monitor profiles…

Just trying to help move these interesting discussions forward.

KeithRJ · February 16, 2023, 11:46am

I fully agree👍🏻

John-M · February 17, 2023, 3:27am

I’m fine with that emphasis, Ian … I don’t print myself, so it’s not particularly relevant for me, personally … But I’m always keen to learn something new.

An interesting point about your suggestion/proposal is that the reason I’ve been “promoting” the importance of understanding Soft Proofing for display purposes (as distinct from printing) is that, “traditionally”, it’s been associated specifically with preparation for printing (as you noted).

It was this image of mine (download link) that first made me realise the criticality of Soft Proofing, including for output to display devices - esp. for images, like this one, containing saturated colours that really push the envelope of target rendering capability (of sRGB devices).

That’s why I felt it important that we all better understood this conflation … and it seems suggestions are that I’ve been “too successful”

Just a point on this, too.(You may already be aware of this - but, allow me to “mansplain” regardless )

(In the context of PL), the means by which Out-of-Gamut colours are “squeezed” into smaller display color spaces (such as sRGB) is via the Preserve Color Details (PCD) algorithm;

During the beta testing stage, we were advised by a DxO staff member that the PCD-algorithm is “neither Perceptual OR Relative Intent - it’s something in-between, developed uniquely by DxO”
By default, the “strength” of application of the PCD-algorithm is a 50/50 split between retention of color saturation versus preservation of detail … and, as you observe, this generally does a very good job.
If we aren’t happy with the default, tho, Soft Proofing’s PCD slider allows us to shift this balance
– My saturated reds image (see link above) is a really good example for testing this with.
Altho it’s not at all obvious from the current (poorly designed) SP user-interface; the PCD slider is applied ONLY when the ICC Profile selected for Soft Proofing is one that applies to display devices (not for printing) … Conversely, the Intent and Paper&Ink simulation options apply ONLY when the ICC Profile selected for Soft Proofing is one that applies to printing (not for display devices)
– See here for my proposal for the Soft Proofing user-interface to be “fixed”.

Go for it, Ian … I will follow with interest.

John

KeithRJ · February 17, 2023, 4:07am

Here is the next iteration of the diagram which I hope will be less confusing and more descriptive of the whole process.

George · February 17, 2023, 6:51am

Still no conversion from soft proof color space to monitor color space

I’ll show you something. I’ve a RGB monitor. When opening an image and turn the soft proof on, the histogram is based on the soft proof image. Choosing another ICC profile gives another histogram. But my image hardly changes. The soft proof image is converted to the monitor profile.
This is also the limitation of soft proofing.

George

IanS · February 17, 2023, 9:14am

We are on the same page John although I am shocked, I repeat shocked, that anyone doesn’t print and I am still trying to understand the concept:slight_smile:

DXO’s improvements to monitor soft proofing are welcome and add value. I agree with you that the SP UI needs further work to clarify what is a complex topic, as seen in the threads on this forum. DXO have done as excellent job so far but with so many users, UI clarity is difficult. In C1 you are always colour soft proofing although some users are unaware that that is what they are doing.

My point is this. Even if you don’t normally print, soft proof a matt paper profile and you will see the contrast and saturation go right down as well as colour changes. Everyone can easily see what is happening even if they only have a monitor with sRGB. So we get a “common” reference point. I hope it would then be easier to understand what’s happening with monitors and profiles. That’s what I tried to show with Joanne’s “lobster” image. That’s turned out to be a very useful image, thanks Joanne.