Blackmagic Forum

Hey, I've read and know about the gamma shift in QuickTime exports. I don't have a problem with gamma shifts when exporting to mxf

But I want to use some stills from a video, exporting to jpeg, tiff or png results in an image with slightly different gamma that how it appears on resolve.

The ones I want to use in the video itself I can freeze frame. But some I have to use outside of the video. And can't seem to get around this problem.

My timeline settings are rec 709 2.4 (tried changing to scene which I don't know exactly what it (scene) is but that doesn't help either)

I don't think deliver page settings do anything in exported still yet the settings are on auto levels. The project settings are on video levels.

The still I am exporting is an ungraded still. 0 nodes or changes. Directly from the video, still from color page and export.

Please help.

Also is there is a platform or group on whatsapp discord or any as such where we can all ask such quick questions. Where a dedicated thread is not needed?

Thanks!

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Mark Foster wrote:https://forum.blackmagicdesign.com/viewtopic.php?f=21&t=101253

I read this. It's mainly for video I suppose. I tried things in it but to no avail. Don't know what am I missing bro

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Any help please?

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Hey guys, any help would be great! i am still having this problem. When exporting stills, there is a tone shift. The darks get a bit lifted.

I have read the above mentioned post and that is not my problem, i do not have problems exporting video, its just the stills from gallery. No matter what i export, jpg, tiff. everything has a slight gamma shift.

did anyone experience this before? any solutions?

What happens if you mark in and out in the Deliver page and export stills (like TIFF)?

If your images have a gamma curve 2.4 but your image reader assumes 2.2 and therefore images appear too dark, then you must assign 2.4 and then convert to 2.2. This can be done in Photoshop under edit menu. Photoshop will tell you upon loading any deviation from the working color space and you can assign and convert accordingly.

Uli Plank wrote:What happens if you mark in and out in the Deliver page and export stills (like TIFF)?

i didnt know we can export stills from the deliver page

Dante Stiller wrote:If your images have a gamma curve 2.4 but your image reader assumes 2.2 and therefore images appear too dark, then you must assign 2.4 and then convert to 2.2. This can be done in Photoshop under edit menu. Photoshop will tell you upon loading any deviation from the working color space and you can assign and convert accordingly.

My working space is 2.4 yes and my monitors are calibrated to 2.4 as well. The exported still is not darker, it is lighter. The blacks are lifted. When i checked in photoshop, the "assign color profile" section, it was set to do not colour manage this file.

If i set this assign color profile to srgb then no change, the darks are still lifted (lighter than in resolve) when i change to adobe rbg it gets darker and normal as it is in davinci. but i dont want to deal with adobe rbg problems when uploading to web for clients or sharing.

If i then convert to profile from adobe RGB to sRGB then this way i can get back to normal contrast. However its taking me so many steps to get stills like this.
1. export still from davinci
2. open in photoshop and assign adobe RGB
3. convert to sRGB and save.

i have a lot of stills to export. there might be a way in davinci to export stills with proper contrast? and not lifted shadows like now?

Also that is not proper math. When I assign Adobe RGB, the colors change a bit. Gets more saturated. I have to tone that down again and that creates some variations

If AdobeRGB to sRGB conversion somewhat works the problem lies in the toe region of transfer function. AdobeRGB and sRGB transfer curves are both 2.2-ish but first is pure gamma curve and another has a linear toe region. So what you could do is try interpreting the tiffs simply as gamma 2.2 / sRGB primaries source and then convert to sRGB, then you get rid of gamut transform which messes with your color saturation.

In Resolve you can try adding Color Space Transform effect with input gamma set to 2.2 and output gamma set to sRGB and see if it produces what you expect as output.

irfanintekhab wrote:
My working space is 2.4 yes and my monitors are calibrated to 2.4 as well. The exported still is not darker, it is lighter. The blacks are lifted. When i checked in photoshop, the "assign color profile" section, it was set to do not colour manage this file.

If i set this assign color profile to srgb then no change, the darks are still lifted (lighter than in resolve) when i change to adobe rbg it gets darker and normal as it is in davinci. but i dont want to deal with adobe rbg problems when uploading to web for clients or sharing.

If i then convert to profile from adobe RGB to sRGB then this way i can get back to normal contrast. However its taking me so many steps to get stills like this.
1. export still from davinci
2. open in photoshop and assign adobe RGB
3. convert to sRGB and save

Also that is not proper math. When I assign Adobe RGB, the colors change a bit. Gets more saturated. I have to tone that down again and that creates some variations

I am not sure what the answers to your problems are but one thing you are doing wrong here for sure is assigning an AdobeRGB Profile and making modifications to the image from there. Assigning a color profile in Photoshop does not change the color numbers, it just changes the way they look on your screen. You can verify this using the eyedropper tool in Photoshop. So you are actually changing the colors yourself by modifying the image after you assign the profile. The general advice from the experts is to only use Assign Profile when you have a file that has no color profile or an incorrect profile. However, it makes no sense here to assign AdobeRGB even if the image is untagged, as that is not what you want in any case. You are only distorting your view of the image.

How about setting the Working Space in Photoshop to sRGB in the Color Settings and then setting it to Convert to Working RGB in the Color Management Policies. That will cut out the unnecessary and misleading step 2 and step 3 becomes automatic. If you find that the images do not look as you want them to then just create an action that will get you in the right ball park if they are all similarly off and/or tweak manually.

mickspixels wrote:How about setting the Working Space in Photoshop to sRGB in the Color Settings and then setting it to Convert to Working RGB in the Color Management Policies. That will cut out the unnecessary and misleading step 2 and step 3 becomes automatic. If you find that the images do not look as you want them to then just create an action that will get you in the right ball park if they are all similarly off and/or tweak manually.

If image does not have profile attached, automatic conversion will not do anything because source colorspace is unknown.

Hendrik Proosa wrote:

mickspixels wrote:.

If image does not have profile attached, automatic conversion will not do anything because source colorspace is unknown.

OK you are right - you need to have Missing Profiles set to Ask When Opening and you get a dialog where you can assign the working space profile (sRGB in this case). When you save the file it will be tagged sRGB. The important point really is he should not be assigning AdobeRGB and making modifications based on what he sees after doing that.

when i change to adobe rbg it gets darker

Have you tried assigning HDTV (rec709) instead of Adobe RGB before converting to sRGB? Adobe RGB is incorrect as you mentioned. It has different primaries and the wrong gamma.

my monitors are calibrated to 2.4 as well

Your desktop is calibrated to rec709? Or just the viewing monitor for Resolve? Rec709 is just for videos. Everything else assumes sRGB.

Dante Stiller wrote:

when i change to adobe rbg it gets darker

Have you tried assigning HDTV (rec709) instead of Adobe RGB before converting to sRGB? Adobe RGB is incorrect as you mentioned. It has different primaries and the wrong gamma.

That would actually be a pointless diversion with no purpose. To reiterate, assigning a profile in Photoshop does nothing to the color numbers, it just alters the appearance of the image. So assigning AdobeRGB is like putting a saturation filter (whatever that might be) over the screen. It will make the image appear more saturated while having no actual effect on the underlying image. Making modifications to the image with such a "filter" is pointless when you are going to convert it to sRGB afterwards as the results will be unpredictable. Assigning a Rec.709 profile would probably make no difference at all in any case as Rec709 and sRGB are very similar but again this would be pointless. It just complicates the workflow and has no purpose.

The simple way to approach this is to convert to sRGB in Photoshop (whichever method you choose to do that) and make any modifications there if sRGB is going to be the final output space. Finally I wonder if it is worth getting too worried about exact matching the stills in Photoshop with the stills in Resolve given that these images are destined for the web it seems and there may be little or no control over how they are viewed in the end.

Op is already doing a conversion, no-one here is arguing that simply changing the profile metadata changes pixel values. Let me quote op again with emphasis:

irfanintekhab wrote:However its taking me so many steps to get stills like this.
1. export still from davinci
2. open in photoshop and assign adobe RGB
3. convert to sRGB and save.

As for this:

mickspixels wrote:So assigning AdobeRGB is like putting a saturation filter (whatever that might be) over the screen. It will make the image appear more saturated while having no actual effect on the underlying image. Making modifications to the image with such a "filter" is pointless when you are going to convert it to sRGB afterwards as the results will be unpredictable.

Assigning AdobeRGB and working under view transform to sRGB or converting first and then working on sRGB data only changes how tools react. It does not distort what one sees, because result is in sRGB space in both cases. If results were unpredictable, it would meal all color management everywhere would not work at all. Yet it does. In one case data flow is:
- AdobeRGB interpreted data > do work > apply view transform to sRGB > look at piece with eyes;
In another case it will be:
- AdobeRGB interpreted data > apply conversion transform to sRGB > do work > apply no view transform > look at piece with eyes;

Adobe RGB is ofcourse wrong, but it does give some clues to what is different and what is similar when conversion from AdobeRGB to sRGB fixes gamma issues but introduces saturation issues. I have already explained my reasoning above about how this could be overcome in Resolve.

I was just trying to keep things simple as the Assign Profile is an unnecessary step whatever profile one assigns and it will affect how one modifies the image while assigned.

So to explain what I mean let's use a simple example.

1.Open an image already tagged sRGB in sRGB working space in Photoshop. Using the Color Sampler tool (under the eyedropper tool) sample a couple of points.

2. Assign an AdobeRGB profile using the Edit-Assign Profile command. Note that the color numbers stay the same but the image will change in appearance (how much will depend on the image of course).

3. Do some edits and save.

4. Repeat the procedure without step 2 and save. Chances are you will have two different looking images. That is the simple point I was making.

Note that if instead of assigning a profile you Convert Profile to AdobeRGB then the color numbers will change.

Hello.

I have same problem. Do you find a solution to this, beside Photoshop work around?

Best
Jaka

I have a simple solution for future reference (probably mine as well next time I have to google this!)

My settings and issues match exactly with the original post - Rec 709 2.4 project. When viewed in Preview, exported stills have a gamma shift making them appear slightly washed out. This is the same whether exporting stills from the Color page or exporting a TIFF sequence.

The issue appears to be that MacOS/Preview can't read the colour profile information that Resolve tags stills with. This can be confirmed by viewing the file info (CMD+I) - a comparison of this info before and after the fix is below.



I discovered that Photoshop reads the colour profile settings correctly, and I also know that when you save a file out of Photoshop that Preview/MacOS will see that colour profile information. So the solution is to either force Photoshop to tag the file as Rec.709 / Gamma 2.4 in a way that MacOS will understand, or actually bake in a conversion from 709/2.4 to sRGB. Both will work, but I opted for the latter as a way to hopefully avoid further issues if those stills ever get opened up on a computer that can't read the 709/2.4 tag properly.

So that's the theory. To apply the fix, open the still in Photoshop and go to Edit > Convert to Profile

A window will open that should tell you that the Source Space is Rec.709 Gamma 2.4.

Either change the Destination Space to Rec.709 Gamma 2.4 or change it to sRGB - up to you as per the explanation above.

Save the file.

Mac OS/Preview will now correctly interpret the colour profile.

I haven't attempted to set this up as a batch action but presumably it's possible for anyone dealing with lots of stills.

Hey Alex -

Thanks for this, in following your directions I've discovered that my output stills from Davinci Resolve are in the profile sRGB iec61966.

This is bizarre and I can't understand it based on my setup. Does anyone recognise why they might be in this color profile?

Thanks

elkins.alex wrote:I have a simple solution for future reference (probably mine as well next time I have to google this!)

My settings and issues match exactly with the original post - Rec 709 2.4 project. When viewed in Preview, exported stills have a gamma shift making them appear slightly washed out. This is the same whether exporting stills from the Color page or exporting a TIFF sequence.

The issue appears to be that MacOS/Preview can't read the colour profile information that Resolve tags stills with. This can be confirmed by viewing the file info (CMD+I) - a comparison of this info before and after the fix is below.

Screenshot 2023-03-31 at 11.03.47.jpg

I discovered that Photoshop reads the colour profile settings correctly, and I also know that when you save a file out of Photoshop that Preview/MacOS will see that colour profile information. So the solution is to either force Photoshop to tag the file as Rec.709 / Gamma 2.4 in a way that MacOS will understand, or actually bake in a conversion from 709/2.4 to sRGB. Both will work, but I opted for the latter as a way to hopefully avoid further issues if those stills ever get opened up on a computer that can't read the 709/2.4 tag properly.

So that's the theory. To apply the fix, open the still in Photoshop and go to Edit > Convert to Profile

A window will open that should tell you that the Source Space is Rec.709 Gamma 2.4.

Either change the Destination Space to Rec.709 Gamma 2.4 or change it to sRGB - up to you as per the explanation above.

Save the file.

Mac OS/Preview will now correctly interpret the colour profile.

I haven't attempted to set this up as a batch action but presumably it's possible for anyone dealing with lots of stills.