Color management/profile confusion - display profile in darktable

Hi everyone,

I’m having difficulty getting color management done right (I think) and it’s been puzzling me for sometime now. What I would like to do is to be able to edit RAW photos in Darktable but it looks like I have stumbled even in the first step to get the colors right before I start editing the photos.
Hopefully I can get advice and insight of what I have done incorrectly from whoever reading this that are far more knowledgeable on this topic.

I have a BenQ SW240 monitor that as an external monitor to my laptop running windows 10. I have also installed ubuntu for dual booting. In both OSes I have Darktable 3.6 installed.
The BenQ monitor I have came factory calibrated and according to the specs, is capable to display 99% adobe RGB color space. The monitor has got build in color modes for AdobeRGB, SRGB, B&W and others. A pictures will look less saturated / more dull when viewed in ‘SRGB’ color mode when compared to ‘AdobeRGB’ color mode. That I gather is how it’s supposed to be since in my understanding the SRGB color space is smaller than that of the AdobeRGB’s.
Here’s the first question that I have. I have a JPEG picture having sRGB color space (straight out from camera) and I don’t understand why this JPEG looks different when viewed on the monitor under both the ‘AdobeRGB’ and ‘sRGB’ color mode.

My subsequent questions are related to the use of color profile in Darktable and the correct behavior I should expect to see.
In Darktable 3.6, for the Display profile, I have selected to use ICC profile that came with the monitor driver. I find that the pictures look more dull with this ICC profile in use when compared to ‘sRGB (web-safe)’ for display profile, when I thought it supposed to be the other way around?

I have also set the softproofing profile as ‘sRGB’ with the purpose of looking at how the picture would look like in sRGB color space and I thought I could compare it to when I set the Display profile to use ‘sRGB’ profile. When I activate the softproofing though, I hardly see any difference in the pictures and it’s definitely not the same as when selecting sRGB as the display profile. Why is it so?

I have tried to export the RAW files as JPEG image file, one with AdobeRGB profile and another with ‘sRGB’ color profile. The JPEG with sRGB color profile are again more vibrant, basically the same look as when I used sRGB for the display profile.

These questions have been bugging me for sometime now and I realize it’s a big confusion for me.

I hadn’t done calibration on the monitor myself since I bought the monitor about 3months ago as I don’t own calibration device yet.

Hope to be able to get insights or correction on my understanding from the people here :slight_smile:

Many thanks,
Don

You have a lot going on with that question. Basically I believe softproofing setting just uses that profile instead of the current display profile …so if you have them both on sRGB they should look the same going to and from softproofing…if they don’t I am not sure what’s up??

I wrote this over a year ago, might be of help:

https://discuss.pixls.us/t/article-color-management-in-raw-processing/11521

Essentially, you’ll want to make a calibrated profile for your monitor soonest. However, if it’s gamut is indeed 99% of AdobeRGB, you could try setting an AdobeRGB ICC profile as the display profile. I currently use a sRGB profile on my tablet in this manner (I have the device, too lazy to do the calibration… ) and it looks okay.

With an appropriate profile set for your display, the software will look for a corresponding profile that describes the image gamut and tone. OOC JPEGs typically don’t have an embedded profile, just a tag that says, “sRGB”, so dt has to have an appropriate profile internally to use. With that profile assigned to the image, the image is transformed for display using it as input and the display profile as output.

Same thing with the raw file. For this, the input profile needs to be one that describes the camera data, these profiles are specific to a camera model. Most raw software has a humougous data set with all the supported camera data, because most cameras do not embed this data in the raw file, go figure. (well cellphones that produce DNG raws do, but they have proven dodgy, ask @Entropy512 )

If you’re playing by the above rules, an image displayed on your monitor should look the same, no matter what colorspace it’s encoded with.

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A display that can cover a wider colour space maps a given RGB input sent to it to a more vivid colour.
When an image is displayed in a colour managed environment, values in the image file are converted values in the display’s colour gamut.
An sRGB triplet, let’s say R = 50, G = 200, B = 50 will need little adjustment to display on an average monitor that covers more or less sRGB. However, the same colour is encoded using different values in Adobe RGB (or in case of a display that is not a close match to sRGB). Inserting the example values (50, 200, 50) in Convert | EasyRGB gives an Adobe RGB triplet of 119.066, 198.675, 67.838. Since the values are much closer together (the ratios are not 1:4), one can see that this colour is not considered so saturated in Adobe RGB (compared to the maximum saturation the colour space is capable of representing).

sRGB 50, 200, 50 means Lab 71.018 -65.575 59.866.

If you set your display profile to sRGB in darktable or your image viewer, no conversion will be made when loading an sRGB image, and 50, 200, 50 will be sent to the display, but that will think the values are in its native colour space (e.g. Adobe RGB or something close to it). Adobe RGB 50, 200, 50 is Lab 67.876 -103.912 64.598; the larger (in absolute value) a and b values mean more saturation.

So, if you want to use your display properly, use its profile as the display profile. A wide-gamut display is not to be used to boost saturation of JPGs; it is to be used to display some colours that no sRGB-encoded JPG can represent (but the cameras can record, some printers can print).

Also a key thing I find is people often have these questions and it comes to light that they don’t do the comparison back in DT or another color managed application but they use the Win10 viewer or some other utility that is not color managed…if you do that you will notice lots of differences when you have a mismatch but if you stay in a color managed environment things should be correctly mapped and displayed between colorspaces…

Thanks for the replies! There is a lot to digest and I will try to reply as soon as I can…

One thing I didn’t mention clearly in my post, in darktable I’ve opened RAW file (mine is taken with Olympus EM-10 MkII) and I was describing the difference in what I observed when different display profile is used. In Darktable the default scene-referred and modern color adaptation is used when opening RAW files
So I’ve tried three display profiles within DT:

  1. BenQ SW240
  2. Adobe RGB (compatible)
  3. sRGB (web-safe)

The first two actually looks quite similar. The third display profile (sRGB) gives me a more saturated look. It’s not that I prefer the saturated look of the sRGB display profile, I just want to know if that is indeed I’ve done the steps correct.

I guess my problem is I’m not sure if with the display profile set to my monitor ICC profile, am I in the right starting point to start editing the raw photos. I’m worries if I adjust the color saturation higher that will end up with super saturated look when I sent the photos for prints or when viewed from web.

Thanks for highlighting this. I saw from other articles about Win10 viewer not being color managed. I’ve used IrfanView to compare the look of the jpgs exported from DT with ‘AdobeRGB’ profile tag and ‘sRGB’ tag (and true enough under Win10 viewer, there is no difference in the look between the two jpgs).

Another odd thing I discovered too that the jpg exported with adobeRGB is having the EXIF color space properties as uncalibrated while the sRGB one is just fine…

edited:
I tried to upload the jpgs here for reference to show what I mean. The exported jpg as sRGB is way oversaturated while the adobeRGB one is just a tad more than what it should be.
I can’t find the way though to upload the images without embedding in the post…


Yes, that is all expected. The BenQ will be close to AdobeRGB, and if you view an sRGB image on a wide gamut monitor without remapping the colours properly (eg. by using an sRGB profile instead of the display’s proper profile, or any application that doesn’t support colour management), it will look overly-saturated.

@priort @kofa @ggbutcher @Matt_Maguire, I really appreciate all the replies and advice given over the weekend and that really cleared up the confusion I had…
@ggbutcher thanks for sharing the article that you wrote, it’s very informative and I learn a lot from it

So just to summarize and conclude in case this will be helpful to others, basically in DT, it’s important to use the correct monitor profile for the display profile. Using the incorrect profile (such as ‘sRGB’ in my case where display that can cover wider color space) would result in the overly saturated looking pictures because of the colors are not mapped properly.

The issue I thought I had with jpg exported with sRGB color space looking much more saturated, it turns out that I have erroneously thought Irfanview was showing me the correct views, but it seems the images were not displayed in the correct color space. Thanks @priort for pointing out this issue.

I have then used both DT and Krita to view and compare the jpgs and voila, the jpgs look OK with very little difference in color, definitely none of the over saturated look. In fact the jpg with sRGB color space is to my eyes, identical to when I used soft proofing function in DT with sRGB profile.

Thanks again to everyone for helping me clear this confusion that’s been bugging me for quite long now!

I have the same screen. You need to use hardware calibration with the BenQ calibration (Palette Master Element) tool and a colorimeter with this screen. There is no way around this. The calibration changes frequently. I need to calibrate it once a month. And that’s also the only way to get a correct profile and use it’s whole gamut.
The profile that came with the driver, you can forget it.
Well, it depends on how often you use it. If you use it for several hours per day, you definitely need to calibrate it once a month.

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Thanks for the advice… I didn’t realize that calibration would need to be done so frequently when I bought this monitor. In fact I decided on this as it came pre-calibrated thinking I didn’t need to get calibration tool.
wrong call, it seems :sweat_smile:

It also depends on how you calibrate it. I made the experience that the calibration is most stable if you calibrate the screen to 6500 kelvin and 120 candela. Apparently it also depends on the temperature in the room where the screen is. Calibration seems to be more stable if it is warmer.
In the end, if you can afford this screen, although it is not the most expensive one, you should also be able to afford a calibration device.
In general, it is recommended to calibrate wide gamut screens every two weeks. So once every 4-8 weeks is actually not so much. But if your calibration settings significantly differ from 6500K/120cd, you should definitely calibrate it every 2 weeks.
Palette Master Element also has an option to check the calibration.

Thanks! I will keep that in mind. will definitely look around for calibration device and get one in near future…

When you do, consider getting a spectrometer-based device. When I bought the ColorMunki colorimeter for display calibration, I was pretty sure that’s all I’d ever need to do. Now, I find myself wanting to measure other things, like light spectrum and color patches, and I wish I’d have just plunked down the extra money back then for the i1Studio spectrometer…

Your Mileage May Vary, here…