Author Topic: Colour profile confusion  (Read 790 times)

2023-03-08, 11:27:02

Jpjapers

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I Have photographed a load of swatches and used a Spyder Checkr to calibrate them in lightroom.
I then saved them as TIF files and open them in photoshop. At this point, photoshop has the ProPhoto profile assigned. Just changing it to sRGB changes the colours so i need to convert to sRGB rather than just Assign the sRGB profile.

So I convert to sRGB profile, the colours still look correct, and I picker the colour to get the hex code. When i put this hex code into a corona color map, it displays incorrectly. And i dont just mean brighter or darker, i mean that something green turns blue. But the hex code is the same.

How can i get the colour that i can see in Lightroom & PS & even illustrator, into max?

I know that theres been many long threads here about colour management and i could really use some advice. Ive been trying for days to figure this out.
I must be doing some process wrong as the colours i see on screen in Adobe products are correct to the real swatches i have. But outside of Adobe software i cant seem to get them to display correctly.


« Last Edit: 2023-03-10, 12:57:00 by Jpjapers »

2023-03-08, 19:30:05
Reply #1

Aram Avetisyan

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I would narrow the issue down to see if the difference is only in Photoshop, or 3ds Max and/or Corona.
Try another program, any, which does not have any profile assigned (so most probably with sRGB), enter the hex color and see if it looks the same as in 3ds Max/Corona.
I think that the other program(s) will have consistent display of the same hex color as 3ds Max/Corona.

Display profiles can get tricky very quickly.

I have just tried in Photoshop, which has sRGB IEC61966-2.1 profile applied (Monitor sRGB) for me, and the sampled hex color had exactly the same RGB values in Photoshop and 3ds Max.
Sampling both previews of the same color - CoronaColor from SME and Photoshop, side by side - there was just a tiny difference, probably because of slight differences in the color profiles for previews.

I think the "difference" is because of the color profile used in Photoshop.

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2023-03-08, 19:51:43
Reply #2

romullus

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If the difference is tiny, then it also could due to rounding errors - Max's colour picker is outdated crap and Corona colour picker is essentially built on top of it and has to deal with all its limitations.
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2023-03-08, 22:07:23
Reply #3

Jpjapers

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I dont think its a corona specific thing i just thought it was best to post here because there has been lots of threads about linear and srgb and colour space etc.

Ive figured out my process for getting colours through from calibrated images in lightroom after watching these videos and essentially immersing myself in the topic all day. So my issue was somewhat of a PEBKAC issue for not knowing much about the mess that is colour management but now ive got my head around embedded profiles things make more sense and ive managed to get my colours in bitmap and in RGB into max correctly (aside from the picker bug i reported today https://forum.corona-renderer.com/index.php?topic=39503.0;topicseen). It looks like my photoshop defaults for colour management were the problem. Once i tagged my lightroom exports with Prophoto embedded, brought it into PS and converted to sRGB everything worked as intended.

These videos were very very informative on this topic and would recommend for anyone struggling to get their head around colour space. The pickers one was also just complete nightmare fuel!



2023-03-09, 10:39:50
Reply #4

Juraj

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All those long threads were effectively about 3dsMax not having any color management, so it will simply stretch towards whatever gamut the current monitor is showing.
Vray has ColorManaged both input (even for colors and textures but the ICC node has to be used) and output (it's in framebuffer).

Assign Profile should never be used, it's meant to be used when you know what color-space the input is, but the color-profile tag was lost, or the file format didn't support.

Photoshop defaults should be to ask what to do, but they can accidently become something else.

Rumour is new 3dsMax might have something to change here. 3dsMax and Corona are somewhat playing a game of cat and mouse who will do it first :- ). It's nightmare for people who need color-critical work, but also it's 2023 and people are adopting wide-gamut in masse thanks to HDR popularity. This will need to change soon.
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2023-03-09, 13:24:00
Reply #5

Jpjapers

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All those long threads were effectively about 3dsMax not having any color management, so it will simply stretch towards whatever gamut the current monitor is showing.
Vray has ColorManaged both input (even for colors and textures but the ICC node has to be used) and output (it's in framebuffer).

Assign Profile should never be used, it's meant to be used when you know what color-space the input is, but the color-profile tag was lost, or the file format didn't support.

Photoshop defaults should be to ask what to do, but they can accidently become something else.

Rumour is new 3dsMax might have something to change here. 3dsMax and Corona are somewhat playing a game of cat and mouse who will do it first :- ). It's nightmare for people who need color-critical work, but also it's 2023 and people are adopting wide-gamut in masse thanks to HDR popularity. This will need to change soon.

I was hoping you might chime in as if i recall, you had a lot to say on the topic.
I basically didnt know how important embedded image profiles were for interchange and how much of a mess colour profiles are between programs but i have been enlightened and now i dont think ill ever not check exif data of anything during interchange or before sending an image to anyone. That was the root of my issue though. i was using photoshop defaults for colour settings and also assigning the sRGB profile rather than converting.

I did find an interesting plugin that offers some colour management but i believe it is only for Vray

https://www.avizstudio.com/tools/acolormanager/

Very interested to see how this topic evolves over the coming years with the adoption of wider gamut monitors. It would make sense that a newer standard than sRGB is adopted given it initially existed for CRT's. I imagine it would be such a mess for a number of years though and there would probably need to be MUCH better colour management in windows. I mean this whole thing has really made me consider buying a Mac for the better OS-Wide management and that has never been something ive considered before!


2023-03-09, 15:02:51
Reply #6

Juraj

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Ever since I bought iPhone I just realize daily how much better is everything solved there. Yes they have it easier but still.

Heh I have two of the best, most expensive Windows laptops in a world. And they can't even keep stable WiFi driver no matter what :- D And how on earth is WiFi driver capable of BSODin the whole system?

Given majority of my clients are US based, I can sleep soundly knowing that if I send them TIFF file with embedded sRGB or wide-gamut DCI-P3/AdobeRGB, I know they will see it correctly. Whereas in Windows, the main photo app (the main one!!) doesn't even support doing that properly.

The only way to have usable experience in Windows across full range of apps, is the NoVideo (just for nVidia) sRGB (it can do others too, incl. ICC) app from Github which superimposes color-profile onto everything, superseding Windows Color Management. This one: https://github.com/ledoge/novideo_srgb It works on laptop too, but you have to disable Optimus and only run dedicated nVidia card.

Windows can't even do HDR well, it can't do color-management well, list just goes forever. How little improvement has Windows11 brought to table is not even worth ranting over :- ).

And 3dsMax only having single gamma value that's also hilarious. I think it's the only DCC app without CC. While I am not such big fan of the VFX influence forcing ACES and .EXR and etc.. at least it will standardize CC across apps. All I wanted was just capability to display with ICC and save with color-profile from framebuffer, ideally in Adobe DNG format.

Ah man, feels good to shit on this topic :- )
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2023-03-10, 11:12:29
Reply #7

Jpjapers

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Ever since I bought iPhone I just realize daily how much better is everything solved there. Yes they have it easier but still.

Heh I have two of the best, most expensive Windows laptops in a world. And they can't even keep stable WiFi driver no matter what :- D And how on earth is WiFi driver capable of BSODin the whole system?

Given majority of my clients are US based, I can sleep soundly knowing that if I send them TIFF file with embedded sRGB or wide-gamut DCI-P3/AdobeRGB, I know they will see it correctly. Whereas in Windows, the main photo app (the main one!!) doesn't even support doing that properly.

The only way to have usable experience in Windows across full range of apps, is the NoVideo (just for nVidia) sRGB (it can do others too, incl. ICC) app from Github which superimposes color-profile onto everything, superseding Windows Color Management. This one: https://github.com/ledoge/novideo_srgb It works on laptop too, but you have to disable Optimus and only run dedicated nVidia card.

Windows can't even do HDR well, it can't do color-management well, list just goes forever. How little improvement has Windows11 brought to table is not even worth ranting over :- ).

And 3dsMax only having single gamma value that's also hilarious. I think it's the only DCC app without CC. While I am not such big fan of the VFX influence forcing ACES and .EXR and etc.. at least it will standardize CC across apps. All I wanted was just capability to display with ICC and save with color-profile from framebuffer, ideally in Adobe DNG format.

Ah man, feels good to shit on this topic :- )

Having never been a mac user, when i asked my colleague to show me the mac colour management dialog i was blown away at the depth of ICC profiles on the retina display. That NoVideo thing looks super useful. I did wonder why nVidia doesnt have a gpu-wide setting for this or even their own calibration device.

A few questions,

In terms of calibration, do you use a calibration device on your monitors? With that NoVideo thing, do you calibrate with or without it enabled? Do you calibrate with it disabled and then enable it?

If a colour falls outside of the sRGB range but it has an sRGB profile attached, will that colour still clamp on a display thats capable of showing the out-of-gamut colour?
Im working on windows but those doing the signoff are on iMacs and im wondering how to go about ensuring that colours translate correctly across devices.

Also, what profile should i be assigning to corona renders? Should i be opening them in Photoshop and assigning the sRGB profile?
« Last Edit: 2023-03-10, 12:57:24 by Jpjapers »

2023-03-11, 00:54:46
Reply #8

Juraj

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I use xRite i1Display Pro, I had it from time when it was the only model supported on wide-gamut Dell Ultrasharps.
I will rather not say if and how much I use it these days... let's just say I am not one of those people calibrating every week, or every month..or even..

Color profiles are well respected on IOS. Doesn't matter what color-space your clients will be working with (but most likely default wide-gamut DCI-P3), it will show sRGB embedded images clamped to sRGB colors. The color profile after all only interprets the RGB values.

The last question is something I actually don't have definite answer for. My opinion is that Corona's output is to be interpreted as sRGB, it looked wrong to me in every other way. Of course, because Corona isn't color managed, without tools like NoVideo Clamp, if someone wants to get identical colors as in Corona (which are shown wrong in every wide-gamut monitor) they will have to assign monitor color profile (and hopefully don't forget to convert back to universal color-space). This will make sure the colors are completely wrong but at least identical :- ).

This is why both 3dsMax and Corona at same time should support Color management as soon as possible. With Corona right now, you only know they use wide-gamut (one that is literally called "wide-gamut", not as in wide-gamut aRGB, ProLab, DCI-P3, ACES,etc..) internally for color calculation. But what kind of operation happens at output? Ondra told me that saving process is managed by 3dsMax. So it's pure black box?

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2023-03-11, 15:49:44
Reply #9

Basshunter

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All I wanted was just capability to display with ICC and save with color-profile from framebuffer, ideally in Adobe DNG format.

I remember asking the devs for this ability to save renders as DNG which would be super helpful in many ways. But I guess it will never be heard.