Changing colorspace on image with pixels set from Python erases all pixels #93714

New Issue

Simon Wendsche · 2021-12-05T18:41:10+01:00

Simon Wendsche commented

2021-12-05 18:41:10 +01:00

Blender Version
Broken: 3.0 (and older)

Short description of error

Image created with Python, pixel values set with foreach_set()
Changing the colorspace erases all pixels, setting them to black

Exact steps for others to reproduce the error

Open this .blend file: image_test.blend

Execute the Python script in the text editor:

import bpy
import random

img = bpy.data.images.new("test", 200, 200, alpha=True, float_buffer=True, is_data=False)

# Fill pixels with colors
img.pixels.foreach_set([random.random() for x in range(200*200*4)])

# Changing the colorspace will set all pixels to black
img.colorspace_settings.name = "Linear"

Expected Behaviour

In my opinion, Blender should convert the pixels from the old colorspace to the new one. The output should be the same as when changing colorspace on an image loaded from disk.

**Blender Version** Broken: 3.0 (and older) **Short description of error** * Image created with Python, pixel values set with `foreach_set()` * Changing the colorspace erases all pixels, setting them to black **Exact steps for others to reproduce the error** Open this .blend file: [image_test.blend](https://archive.blender.org/developer/F12692495/image_test.blend) Execute the Python script in the text editor: ```Py import bpy import random img = bpy.data.images.new("test", 200, 200, alpha=True, float_buffer=True, is_data=False) # Fill pixels with colors img.pixels.foreach_set([random.random() for x in range(200*200*4)]) # Changing the colorspace will set all pixels to black img.colorspace_settings.name = "Linear" ``` **Expected Behaviour** In my opinion, Blender should convert the pixels from the old colorspace to the new one. The output should be the same as when changing colorspace on an image loaded from disk.

👍 1

Simon Wendsche commented

2021-12-05 18:41:10 +01:00

Added subscriber: @BYOB

Richard Antalik commented

2021-12-06 21:19:19 +01:00

Added subscriber: @iss

Richard Antalik commented

2021-12-06 21:19:19 +01:00

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

Richard Antalik commented

2021-12-06 21:19:19 +01:00

Image buffer content is supposed to be in common colorspace - Linear if buffer is float, sRGB otherwise. All operations rely on this. You specify only in what colorspace image is saved on disk. Since this image is generated, setting it's colorspace is "not valid" operation. This is because file format does inform what colorspace should be (it is not possible to save linear data in PNG format, this is same for render result/bakes, conversion happens when file is saved to disk).

Not quite sure why changing colorspace is allowed for predefined generated images. Also I think this could be sanitized in RNA rather than just disabling this in UI.

I will confirm as I think this could be handled in better way, but this may be closed as "not a bug".

Image buffer content is supposed to be in common colorspace - Linear if buffer is float, sRGB otherwise. All operations rely on this. You specify only in what colorspace image is saved on disk. Since this image is generated, setting it's colorspace is "not valid" operation. This is because file format does inform what colorspace should be (it is not possible to save linear data in PNG format, this is same for render result/bakes, conversion happens when file is saved to disk). Not quite sure why changing colorspace is allowed for predefined generated images. Also I think this could be sanitized in RNA rather than just disabling this in UI. I will confirm as I think this could be handled in better way, but this may be closed as "not a bug".

Brecht Van Lommel commented

2021-12-08 21:26:05 +01:00

Added subscriber: @brecht

Brecht Van Lommel commented

2021-12-08 21:26:05 +01:00

I think that for generated images we can just make it not reload / regenerate the image.

There's two reason why you still might want to have this color space editable for generated images:

Most color spaces should not matter, however setting the color space to non-color data should make a difference.
It can be useful to set the color space in anticipation of saving the image to disk.

I think that for generated images we can just make it not reload / regenerate the image. There's two reason why you still might want to have this color space editable for generated images: * Most color spaces should not matter, however setting the color space to non-color data should make a difference. * It can be useful to set the color space in anticipation of saving the image to disk.

👍 1

Bastien Montagne added this to the Core project 2023-02-09 15:42:54 +01:00

Bastien Montagne removed this from the Core project 2023-02-09 18:20:37 +01:00

Philipp Oeser removed the

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Changing colorspace on image with pixels set from Python erases all pixels #93714