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Convert Color Space Node is undocumented. #95186

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opened 2022-01-24 21:02:16 +01:00 by kevin donovan · 9 comments
kevin donovan commented 2022-01-24 21:02:16 +01:00
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The Convert Color Space Node is currently undocumented in the 3.1 version of the manual.
I have chosen to repurpose this task instead of closing it, to note that the image node's sRGB->Linear automatic transformation might cause confusion to other users, and therefor I think it should be documented on the Convert Color Space Node's page.

Original report below

Original Title
srgb to filmic log colorspace convert not correct

System Information
Operating system: Windows-10-10.0.22000-SP0 64 Bits
Graphics card: AMD Radeon RX 5700 ATI Technologies Inc. 4.5.14802 Core Profile Context 22.1.1 30.0.14023.1009

Blender Version
Broken: version: 3.1.0 Alpha, branch: master, commit date: 2022-01-23 19:27, hash: blender/blender@abf30007ab
Worked: (newest version of Blender that worked as expected)

Short description of error
using the srgb to filmic colorspace conversion(node) settings does not give the correction numbers.
using the view transform for filmic log to test the color managed numbers which should become the non cm rgb numbers after conversion
The numbers are correct for linear to filmic log but not srg to filmic log.

Exact steps for others to reproduce the error
use the color space conversion node to convert and srgb image to filmic log, If you switch to the filmic log view transform (blender color management) the
the cm rgb numbers should be the same as the number the rgb numbers after the conversion. Meaning the previous cm rgb number under filmic log view transform should should match the the straight rgb numbers after the colorspace transform node srgb to filmiclog. this works with linear to filmic colorspace transform but not srgb to filmic.

srgb_gray.jpg

lin_gray.exr

The Convert Color Space Node is currently undocumented in the 3.1 version of the manual. I have chosen to repurpose this task instead of closing it, to note that the image node's `sRGB->Linear` automatic transformation might cause confusion to other users, and therefor I think it should be documented on the Convert Color Space Node's page. **Original report below** **Original Title** srgb to filmic log colorspace convert not correct **System Information** Operating system: Windows-10-10.0.22000-SP0 64 Bits Graphics card: AMD Radeon RX 5700 ATI Technologies Inc. 4.5.14802 Core Profile Context 22.1.1 30.0.14023.1009 **Blender Version** Broken: version: 3.1.0 Alpha, branch: master, commit date: 2022-01-23 19:27, hash: `blender/blender@abf30007ab` Worked: (newest version of Blender that worked as expected) **Short description of error** using the srgb to filmic colorspace conversion(node) settings does not give the correction numbers. using the view transform for filmic log to test the color managed numbers which should become the non cm rgb numbers after conversion The numbers are correct for linear to filmic log but not srg to filmic log. **Exact steps for others to reproduce the error** use the color space conversion node to convert and srgb image to filmic log, If you switch to the filmic log view transform (blender color management) the the cm rgb numbers should be the same as the number the rgb numbers after the conversion. Meaning the previous cm rgb number under filmic log view transform should should match the the straight rgb numbers after the colorspace transform node srgb to filmiclog. this works with linear to filmic colorspace transform but not srgb to filmic. ![srgb_gray.jpg](https://archive.blender.org/developer/F12821762/srgb_gray.jpg) ![lin_gray.exr](https://archive.blender.org/developer/F12821761/lin_gray.exr)
kevin donovan commented 2022-01-24 21:02:16 +01:00
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kevin donovan commented 2022-01-24 21:23:28 +01:00
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added a linear gray and srgb grey when using filmiclog view transform we get the same conversion , but when using the color space conversion node we get different numbers.

added a linear gray and srgb grey when using filmiclog view transform we get the same conversion , but when using the color space conversion node we get different numbers.
Evan Wilson commented 2022-01-25 02:42:43 +01:00
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Added subscriber: @EAW

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Evan Wilson commented 2022-01-25 02:42:43 +01:00
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Changed status from 'Needs Triage' to: 'Confirmed'

Changed status from 'Needs Triage' to: 'Confirmed'
Evan Wilson commented 2022-01-25 02:42:43 +01:00
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Thank you for the report.
NOTE:It is always helpful, when saying that the numbers don't match, to say what those numbers are, and also what the expected numbers are.

NOTE: Please also to include a .blend file demonstrating the issue.

Blender takes an sRGB image and converts it to Linear when loading the image, if the image's color space is set to sRGB.
The Image node is outputting Linear data already, that is why setting the color space conversion node from Linear to Filmic Log will give you the desired results.
If you set the sRGB image's color space to Raw, you are telling Blender "Just give me the raw data stored in the file, don't convert it for me."
Then setting the color space conversion node from sRGB to Filmic Log works as seen in the Blender file and screenshot below.

#95186 sRGB to Filmic Log Comp Node.blend

#95186 sRGB to Filmic Log Comp Node.png

As there hasn't been any information committed to the manual regarding the new Color Space Conversion Node, I'll leave this open as a documentation task to be sure to add a note about this in the manual.

Thank you for the report. NOTE:It is always helpful, when saying that the numbers don't match, to say what those numbers are, and also what the expected numbers are. NOTE: Please also to include a .blend file demonstrating the issue. Blender takes an sRGB image and converts it to Linear when loading the image, if the image's color space is set to `sRGB`. The Image node is outputting Linear data already, that is why setting the color space conversion node from `Linear` to `Filmic Log` will give you the desired results. If you set the sRGB image's color space to `Raw`, you are telling Blender "*Just give me the raw data stored in the file, don't convert it for me.*" Then setting the color space conversion node from `sRGB` to `Filmic Log` works as seen in the Blender file and screenshot below. [#95186 sRGB to Filmic Log Comp Node.blend](https://archive.blender.org/developer/F12822201/T95186_sRGB_to_Filmic_Log_Comp_Node.blend) ![#95186 sRGB to Filmic Log Comp Node.png](https://archive.blender.org/developer/F12822202/T95186_sRGB_to_Filmic_Log_Comp_Node.png) --- As there hasn't been any information committed to the manual regarding the new Color Space Conversion Node, I'll leave this open as a documentation task to be sure to add a note about this in the manual.
Evan Wilson changed title from srgb to filmic log colorspace convert not correct to Convert Color Space Node is undocumented. 2022-01-25 09:58:23 +01:00
kevin donovan commented 2022-01-25 12:52:17 +01:00
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Thanks for looking into this. It does make me wonder how the lut node will handle inputs if its ever accepted. Maybe in the future
a check box on the color space node to delinear based on input selection would be helpful, so we can keep all the comping linear before
the color space node

Thanks for looking into this. It does make me wonder how the lut node will handle inputs if its ever accepted. Maybe in the future a check box on the color space node to delinear based on input selection would be helpful, so we can keep all the comping linear before the color space node
Aaron Carlisle commented 2022-02-09 21:40:20 +01:00
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Aaron Carlisle commented 2022-02-09 21:40:20 +01:00
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Changed status from 'Confirmed' to: 'Resolved'

Changed status from 'Confirmed' to: 'Resolved'
Aaron Carlisle self-assigned this 2022-02-09 21:40:20 +01:00
Aaron Carlisle commented 2022-02-09 21:40:20 +01:00
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Node has now been documented

Node has now been documented
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