Regression: image.save_render() command changes color profile and file type when saving. #98444

New Issue

Eugenio Pignataro · 2022-05-27T15:31:11+02:00

Eugenio Pignataro commented

2022-05-27 15:31:11 +02:00

Ubuntu 22.04
Nvidia 1070 Ti

Broken: version: 3.3.0 Alpha May 18 89ccff62d2
Worked: 3.2 May 2 5188c14718

When you save a newly baked float Normal Image with Linear profile using the bpy.data.images["Untitled"].save_render("/path/to/save/file.exr") command, blender saves it as a 16 bit PNG with sRGB values and a .exr extension.

Previously it would save the image buffer as a linear OpenEXR Image file.

Steps:
1 -Bake a float normal map in memory in Linear color profile
2 - Save the picture with save_render python command.
3 - open the .exr in image editor.
4 - You will see the color profile loaded as sRGB.
5 - Various other programs won't open it because it is actually a 16 bit PNG file with the wrong extension.

blendFile: test.blend

Working video 3.2: https://www.dropbox.com/s/e4mat4i77ix6i7q/2022-05-27%2010-18-27.mp4?dl=0
Non Working video 3.3: https://www.dropbox.com/s/35x24pobe6plafp/2022-05-27%2010-21-14.mp4?dl=0

Same procedure, different result.

Ubuntu 22.04 Nvidia 1070 Ti Broken: version: 3.3.0 Alpha May 18 89ccff62d2df Worked: 3.2 May 2 5188c14718c5 When you save a newly baked float Normal Image with Linear profile using the `bpy.data.images["Untitled"].save_render("/path/to/save/file.exr")` command, blender saves it as a 16 bit PNG with sRGB values and a `.exr` extension. Previously it would save the image buffer as a linear OpenEXR Image file. Steps: 1 -Bake a float normal map in memory in Linear color profile 2 - Save the picture with save_render python command. 3 - open the `.exr` in image editor. 4 - You will see the color profile loaded as sRGB. 5 - Various other programs won't open it because it is actually a 16 bit PNG file with the wrong extension. blendFile: [test.blend](https://archive.blender.org/developer/F13114799/test.blend) Working video 3.2: https://www.dropbox.com/s/e4mat4i77ix6i7q/2022-05-27%2010-18-27.mp4?dl=0 Non Working video 3.3: https://www.dropbox.com/s/35x24pobe6plafp/2022-05-27%2010-21-14.mp4?dl=0 Same procedure, different result.

Eugenio Pignataro commented

2022-05-27 15:31:11 +02:00

Added subscriber: @EugenioPignataro

Omar Emara commented

2022-05-27 16:02:42 +02:00

Added subscriber: @OmarEmaraDev

Omar Emara commented

2022-05-27 16:02:42 +02:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Omar Emara commented

2022-05-27 16:02:42 +02:00

Does EXR images store color profiles at all? As far as I know, EXR files can't store the color space, so this is most likely Blender assuming a color space upon reading the image back.
It loads as linear for me regardless. Does this happen with the default OCIO config and factory settings?

Does EXR images store color profiles at all? As far as I know, EXR files can't store the color space, so this is most likely Blender assuming a color space upon reading the image back. It loads as linear for me regardless. Does this happen with the default OCIO config and factory settings?

Eugenio Pignataro commented

2022-05-27 16:14:16 +02:00

Hi Omar! In the previous versions this worked fine.

Blender saves pixel information baked as sRGB.

If I set the image loaded as Linear (normal map):

Hi Omar! In the previous versions this worked fine. Blender saves pixel information baked as sRGB. ![image.png](https://archive.blender.org/developer/F13114775/image.png) If I set the image loaded as Linear (normal map): ![image.png](https://archive.blender.org/developer/F13114778/image.png)

Eugenio Pignataro commented

2022-05-27 16:21:24 +02:00

I've tried with default OCIO, same problem.

I made a new video:

https://www.dropbox.com/s/xnrbfgnproc5tko/2022-05-27%2011-18-33.mp4?dl=0

blendFile: test.blend

I've tried with default OCIO, same problem. I made a new video: https://www.dropbox.com/s/xnrbfgnproc5tko/2022-05-27%2011-18-33.mp4?dl=0 blendFile: [test.blend](https://archive.blender.org/developer/F13114799/test.blend)

Eugenio Pignataro commented

2022-05-27 16:24:04 +02:00

This is an older .exr in the newest blender version.
it's working fine.
I believe that the problem is in the save step.

This is an older .exr in the newest blender version. it's working fine. I believe that the problem is in the save step. ![image.png](https://archive.blender.org/developer/F13114803/image.png)

Omar Emara commented

2022-05-27 16:38:26 +02:00

In 3.2 in your video, it seems to be loaded as sRGB OETF, not linear, which is contrary to what you want, right?
It loads as sRGB in both versions for me. My point was that EXR files don't actually store any color space information, so Blender make make the decision based on something else.

In 3.2 in your video, it seems to be loaded as `sRGB OETF`, not linear, which is contrary to what you want, right? It loads as sRGB in both versions for me. My point was that EXR files don't actually store any color space information, so Blender make make the decision based on something else.

Eugenio Pignataro commented

2022-05-27 18:39:34 +02:00

Hi Omar, we are testing the last blender build with my partner.

We are close to find the problem.

The last version it seems to be using color management options for saving the file.

The previous versions doesn't force the use of the CM options to save the images with "save_render()"

The usual way to load an EXR Normal Map is in Linear, and the undistorted base value is .5 .5 1

Hi Omar, we are testing the last blender build with my partner. We are close to find the problem. The last version it seems to be using color management options for saving the file. The previous versions doesn't force the use of the CM options to save the images with "save_render()" The usual way to load an EXR Normal Map is in Linear, and the undistorted base value is .5 .5 1

Omar Emara commented

2022-05-27 18:42:33 +02:00

Changed status from 'Needs User Info' to: 'Needs Triage'

Nahuel Belich commented

2022-05-27 19:01:02 +02:00

Added subscriber: @NahuelBelich

Nahuel Belich commented

2022-05-27 19:01:02 +02:00

I have the blender defaults color management and notice the same behaviuor with the test file provided in the comments(following the steps).
With the blender default i can reproduce the problem, its using the Color management options instead of saving linear. This may or not be a big issue but something to consider, however we also notice a second big (huge) issue that could be related to this, saving exr files using the console can no longer be opened with Krita, it returns an error
(QString::arg: Argument missing: Loading canceled. Error:)
nor can be opened in djview imagin 2.0.6

Working properly build:
hash: 56d1d19c88
commit date: 2022-04-20 14:55

oldest failing build i have
hash: 89ccff62d2
commit date: 2022-05-18 21:09

I have the blender defaults color management and notice the same behaviuor with the test file provided in the comments(following the steps). With the blender default i can reproduce the problem, its using the Color management options instead of saving linear. This may or not be a big issue but something to consider, however we also notice a second big (huge) issue that could be related to this, saving exr files using the console can no longer be opened with Krita, it returns an error (QString::arg: Argument missing: Loading canceled. Error:) nor can be opened in djview imagin 2.0.6 ![image.png](https://archive.blender.org/developer/F13115163/image.png) Working properly build: hash: 56d1d19c88e0 commit date: 2022-04-20 14:55 oldest failing build i have hash: 89ccff62d2df commit date: 2022-05-18 21:09

Evan Wilson commented

2022-05-28 07:38:53 +02:00

Added subscriber: @EAW

Evan Wilson commented

2022-05-28 07:38:53 +02:00

Changed status from 'Needs Triage' to: 'Confirmed'

Evan Wilson commented

2022-05-28 07:38:53 +02:00

I can confirm.

Sorry my bad english and thanks a bunch!

@EugenioPignataro your English is perfectly understandable. 😀

saving exr files using the console can no longer be opened with Krita, it returns an error
nor can be opened in djview imagin 2.0.6

@NahuelBelich It turns out that Blender is saving them as 16bit PNG files with the .exr extension.

Ifranview 4.58 gives the error message of

Warning!
The File: "C:\home\tomate\defaultOCIO.exr" is a PNG file with incorrect extension.
Rename?

Examining the file in a HEX editor confirms that it is a PNG file. Changing the extension allows the file to be opened normally.

I'll update the report.

I won't be able to bisect until tommorow.

I can confirm. >Sorry my bad english and thanks a bunch! @EugenioPignataro your English is perfectly understandable. 😀 >saving exr files using the console can no longer be opened with Krita, it returns an error >nor can be opened in djview imagin 2.0.6 @NahuelBelich It turns out that Blender is saving them as 16bit PNG files with the .exr extension. Ifranview 4.58 gives the error message of >Warning! >The File: "C:\home\tomate\defaultOCIO.exr" is a PNG file with incorrect extension. >Rename? Examining the file in a HEX editor confirms that it is a PNG file. Changing the extension allows the file to be opened normally. I'll update the report. I won't be able to bisect until tommorow.

Evan Wilson changed title from ~~Error image.save_render() command color profile.~~ to Regression: image.save_render() command changes color profile and file type when saving.

2022-05-28 08:02:00 +02:00

Eugenio Pignataro commented

2022-05-28 12:26:09 +02:00

Ohh thanks Evan! thanks Omar.
We are working on a PBR Baker Addon, so... save_render command is very important for us.

thank you very much again!

Ohh thanks Evan! thanks Omar. We are working on a PBR Baker Addon, so... save_render command is very important for us. thank you very much again!

Bastien Montagne commented

2022-05-30 11:27:54 +02:00

Added subscribers: @brecht, @mont29

Bastien Montagne commented

2022-05-30 11:27:54 +02:00

@brecht this one might be for you I think? Thanks.

Brecht Van Lommel commented

2022-05-30 14:14:04 +02:00

I'll restore the old behavior.

Note that technically normal maps should be set to Non-Color instead of Linear. With the default OpenColorIO config you might not notice the difference, but in general it will not work correctly.

I'll restore the old behavior. Note that technically normal maps should be set to Non-Color instead of Linear. With the default OpenColorIO config you might not notice the difference, but in general it will not work correctly.

blender-admin commented

2022-05-30 14:23:45 +02:00

This issue was referenced by fc1ae52994

This issue was referenced by fc1ae52994016fc4d43053caa412212726f7e223

Brecht Van Lommel commented

2022-05-30 15:36:41 +02:00

Changed status from 'Confirmed' to: 'Archived'

Brecht Van Lommel closed this issue

2022-05-30 15:36:41 +02:00

Brecht Van Lommel commented

2022-05-30 15:36:41 +02:00

Actually, looking closer I don't think this is a bug.

Blender 3.1.2, 3.2 and 3.3 are all saving a PNG file with EXR extension. It uses the settings in the Output panel, the extension in the file path is not what determines the file type.

The difference is in this bugfix from 5baa3ec.

* Fix missing color space conversion for 16 bit PNGs, where it assumed wrongly
  assumed ibuf->rect would be used for saving. Add BKE_image_format_is_byte to
  more accurately test this.

That is, 16 bit PNG would save renders without color space conversion (i.e. Linear), while 8 bit PNG would do the proper color space conversion. However both should work the same way, PNG files have a 0..1 range and can't store linear HDR colors, regardless if it's 8 bit or 16 bit.

If you want to save a non-color image through the render pipeline, you need to either:

Change the output file type to EXR
Set the view transform to Raw for other file types

Actually, looking closer I don't think this is a bug. Blender 3.1.2, 3.2 and 3.3 are all saving a PNG file with EXR extension. It uses the settings in the Output panel, the extension in the file path is not what determines the file type. The difference is in this bugfix from 5baa3ec. > * Fix missing color space conversion for 16 bit PNGs, where it assumed wrongly > assumed ibuf->rect would be used for saving. Add BKE_image_format_is_byte to > more accurately test this. That is, 16 bit PNG would save renders without color space conversion (i.e. Linear), while 8 bit PNG would do the proper color space conversion. However both should work the same way, PNG files have a 0..1 range and can't store linear HDR colors, regardless if it's 8 bit or 16 bit. If you want to save a non-color image through the render pipeline, you need to either: * Change the output file type to EXR * Set the view transform to Raw for other file types

Eugenio Pignataro commented

2022-05-30 16:00:52 +02:00

Hi Bretch, thanks for your help.

I'm following your instructions:

Output

CM

Run command:
bpy.data.images['Untitled'].save_render("/home/tomate/test.exr")

Djv error:

What am I doing wrong?

If I save the picture from uv/imageEditor space everything works fine!

Save as:

Djv works fine:

And blender recognizes the color profile.

I tried everything, but I can't get a good result.

Thanks a bunch.

Hi Bretch, thanks for your help. I'm following your instructions: Output ![image.png](https://archive.blender.org/developer/F13123106/image.png) CM ![image.png](https://archive.blender.org/developer/F13123115/image.png) Run command: bpy.data.images['Untitled'].save_render("/home/tomate/test.exr") Djv error: ![image.png](https://archive.blender.org/developer/F13123119/image.png) What am I doing wrong? If I save the picture from uv/imageEditor space everything works fine! Save as: ![Screenshot from 2022-05-30 10-56-30.png](https://archive.blender.org/developer/F13123131/Screenshot_from_2022-05-30_10-56-30.png) Djv works fine: ![image.png](https://archive.blender.org/developer/F13123137/image.png) And blender recognizes the color profile. ![Screenshot from 2022-05-30 10-57-41.png](https://archive.blender.org/developer/F13123140/Screenshot_from_2022-05-30_10-57-41.png) I tried everything, but I can't get a good result. Thanks a bunch.

Brecht Van Lommel commented

2022-05-30 16:26:28 +02:00

Ok, it seems there is a bug where this output setting is ignored. It was confusing because the example blend had this set to PNG while presumably your real test case had it set to EXR.

Brecht Van Lommel commented

2022-05-30 16:26:36 +02:00

Changed status from 'Archived' to: 'Resolved'

Eugenio Pignataro commented

2022-05-30 17:11:37 +02:00

Now blender works fine!

Thanks Brecht!

Now blender works fine! Thanks Brecht!

blender-admin commented

2022-05-30 17:17:39 +02:00

This issue was referenced by None@62938

Thomas Dinges added this to the 3.2 milestone 2023-02-08 15:51:07 +01:00

Sign in to join this conversation.

No Label

Download

What's New

Blender Studio

Manual

Developers Blog

Documentation

Benchmark

Blender Conference

Development Fund

One-time Donations

Regression: image.save_render() command changes color profile and file type when saving. #98444