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In compositing, the Render Layers node is outputting a HDR (32bit?) image. I'm trying to add a white background and a gradient using compositing nodes, but sRGB nodes are interpreteted as some middle-grey color.

Can I transform the Render Layer Image node to sRGB first, and do my opererations after? What node would I use for this?

(edit: as per the comments below, using the correct naming sRGB instead of RGB)

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  • $\begingroup$ Note that it's all RGB all the time in Blender. You might mean to say sRGB. sRGB is a specific RGB color space and RGB without the "s" is the whole color model that uses red, green and blue lights to represent color. It can have infinite amount of color spaces. All compositing in Blender is done in RGB color model, but in linear color space. There are other color models/systems like CMYK. Saying RGB(or just CMYK) does not describe the color space, just a model/system and 32bit HDR files still use RGB model. That's a common mistake even amongst professionals in areas like graphics design. $\endgroup$ Oct 24, 2023 at 21:15
  • $\begingroup$ It's a pity to see many professionals make this horrible mistake. But it's so common... Every time a graphics designer gives you a hex code for a color without specifying the color space for example, they are are being unprofessional. Or a print shop requesting the files to be in "CMYK color space"... It's just a model, not color space. I have seen countless designers working on their Macs with P3 color space monitors and giving hex codes to their clients using sRGB monitors... it's truly disgusting. Don't make this mistake. $\endgroup$ Oct 24, 2023 at 21:22
  • $\begingroup$ Thank you Martynas. I've corrected the question accordingly (with a note so future visitors may understand what happened here :)) $\endgroup$
    – Warner
    Oct 25, 2023 at 6:26
  • $\begingroup$ Nodes with color inputs in compositing are in linear RGB color space(Rec. 709 chromaticities and D65 white point), not sRGB. Rendering and compositing happens in that space, images are converted to it for rendering then color managment is applied at the end and colors are transformed to the space of Display Device setting so sRGB. New versions will have settings for other screens as well, hopefully it works. At the moment if you have custom color management ssetup and let's say P3 display devices, files are saved incorrectly. $\endgroup$ Oct 25, 2023 at 6:36

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Blender uses Filmic color transform(shortly with version 4.0 will use new version of it - AgX), that compresses light values and makes highlights visible so they don't loose detail and look more natural as well. This also makes RGB(1,1,1) look greyish. You just need a higher value to show white after Filmic transform. Try something like RGB(20,20,20) with Filmic/AgX:

enter image description here

Or you could disable Filmic/AgX transform by choosing "Standard" transform in the Color Management settings:

enter image description here

In this case, your renders will not use Filmic/AgX, but the color values will just be clipped at some point instead of compressed in a sophisticated and nice looking way, so everything might start looking real ugly in case of your renders based on scene referred light values, but if you are compositing images that are not 32bit EXRs in linear color space and start with sRGB images in the first place, that's probably what you would want.

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  • $\begingroup$ That's great, thank you for the insight. If I want to start with filmic (because I want to apply some Glare effects that benefit from it) and then add a white background, is that possible? I tried to use the 'Convert Colorspace' node from Raw to sRGB but it's not showing any difference. $\endgroup$
    – Warner
    Oct 25, 2023 at 6:23
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    $\begingroup$ Ok, nevermind.. just set the color values to (15,15,15) for the background, got it! $\endgroup$
    – Warner
    Oct 25, 2023 at 6:29
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    $\begingroup$ I think white in Filmic is $2^{6.5} × 0.18 ≈ 16.29174$ $\endgroup$ Oct 25, 2023 at 9:39
  • $\begingroup$ OK, let's make it 20. $\endgroup$ Oct 25, 2023 at 10:49
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    $\begingroup$ @MarkusvonBroady you are right. It's in the readme on Filmic GitHub page. It's 16.29174024. $\endgroup$ Oct 25, 2023 at 10:52

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