Blue on cropped part of image when Sequencer color space is Linear #85003

New Issue

Corwin Kerr · 2021-01-23T22:03:21+01:00

Corwin Kerr commented

2021-01-23 22:03:21 +01:00

System Information
Operating system: Darwin-19.6.0-x86_64-i386-64bit 64 Bits
Graphics card: AMD Radeon Pro 5500M OpenGL Engine ATI Technologies Inc. 4.1 ATI-3.10.18

Blender Version
Broken: version: 2.93.0 Alpha, branch: master, commit date: 2021-01-22 18:30, hash: aaa1d58054
Broken: version: 2.92.0 Beta, branch: master, commit date: 2021-01-15 20:18, hash: 957de39191
Worked: version: 2.91.0, branch: master, commit date: 2020-11-25 08:34, hash: 0f45cab862

Short description of error
When using the Linear color space for the sequencer, a cyan blue color appears where the cropped part of the image should be. It appears best when placed over a white color strip. I'm not sure if it works on all images.

Setting Color>Saturation != 1 makes the cropped area turn black.
Changing Color>Multiply doesn't affect it.

I don't know if this is due to misuse of color spaces.

Exact steps for others to reproduce the error

Here is how I made the example file:

Note default Sequencer color space is sRGB.

Open new video sequencer file.
Add a color strip and set it to white extending over enough space for 2 images to be added.
Add an image as alpha over and position cursor over image.
Crop it using the new transform tools.
Change sequencer color space to "Linear". Note things look normal.
Position cursor above just the color strip.
Add an image as alpha over.
Crop it using transform tools.
Observe cyan blue in place where uncropped image would be
Render the frame of animation.
Note the render and preview appear as they should.
Move cursor
Problem re-appears.
Do anything to cause the first strip to re-load (like save and open) and the first strip has the problem too.

In the example file I also cropped the color strip to show that the blue only appears where the color generator strip is.

Based on attached .blend file.
blue_cropped_on_alpha_over.blend

**System Information** Operating system: Darwin-19.6.0-x86_64-i386-64bit 64 Bits Graphics card: AMD Radeon Pro 5500M OpenGL Engine ATI Technologies Inc. 4.1 ATI-3.10.18 **Blender Version** Broken: version: 2.93.0 Alpha, branch: master, commit date: 2021-01-22 18:30, hash: `aaa1d58054` Broken: version: 2.92.0 Beta, branch: master, commit date: 2021-01-15 20:18, hash: `957de39191` Worked: version: 2.91.0, branch: master, commit date: 2020-11-25 08:34, hash: `0f45cab862` **Short description of error** When using the Linear color space for the sequencer, a cyan blue color appears where the cropped part of the image should be. It appears best when placed over a white color strip. I'm not sure if it works on all images. Setting Color>Saturation != 1 makes the cropped area turn black. Changing Color>Multiply doesn't affect it. I don't know if this is due to misuse of color spaces. ![blue_crop_problem.png](https://archive.blender.org/developer/F9594293/blue_crop_problem.png) **Exact steps for others to reproduce the error** Here is how I made the example file: Note default Sequencer color space is sRGB. 1. Open new video sequencer file. 2. Add a color strip and set it to white extending over enough space for 2 images to be added. 3. Add an image as alpha over and position cursor over image. 4. Crop it using the new transform tools. 5. Change sequencer color space to "Linear". Note things look normal. 6. Position cursor above just the color strip. 7. Add an image as alpha over. 8. Crop it using transform tools. 9. Observe cyan blue in place where uncropped image would be 10. Render the frame of animation. 11. Note the render **and** preview appear as they should. 12. Move cursor 13. Problem re-appears. 14. Do anything to cause the first strip to re-load (like save and open) and the first strip has the problem too. In the example file I also cropped the color strip to show that the blue only appears where the color generator strip is. Based on attached .blend file. [blue_cropped_on_alpha_over.blend](https://archive.blender.org/developer/F9594296/blue_cropped_on_alpha_over.blend)

Corwin Kerr commented

2021-01-23 22:03:21 +01:00

Added subscriber: @ckerr

Richard Antalik commented

2021-01-24 03:13:00 +01:00

Added subscriber: @iss

Richard Antalik commented

2021-01-24 03:13:00 +01:00

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

Richard Antalik commented

2021-01-24 03:13:00 +01:00

Can you provide image file?
What are steps with provided .blend file? I assume I should start from step 9?

Can you provide image file? What are steps with provided .blend file? I assume I should start from step 9?

Corwin Kerr commented

2021-01-24 03:18:52 +01:00

Here's the image unpacked from the .blend.

I have tested a few different images and it's not obviously linked to the image.

Yes for the attached file, start from 9.
I just confirmed by re-downloading it - the problem shows up in the preview right away when I open the .blend file.

Here's the image unpacked from the .blend. ![weird-alpha.png](https://archive.blender.org/developer/F9594571/weird-alpha.png) I have tested a few different images and it's not obviously linked to the image. Yes for the attached file, start from 9. I just confirmed by re-downloading it - the problem shows up in the preview right away when I open the .blend file.

Richard Antalik commented

2021-01-24 03:34:39 +01:00

I can't reproduce this issue. Based on description I would assume it can be duplicate of #82094 as convert to float should change strip colorspace to linear.

Can youy check without changing colorspace in rendering panel and just using convert to float option on strip?

I can't reproduce this issue. Based on description I would assume it can be duplicate of #82094 as convert to float should change strip colorspace to linear. Can youy check without changing colorspace in rendering panel and just using convert to float option on strip?

Corwin Kerr commented

2021-01-24 03:45:32 +01:00

without changing colorspace in rendering panel and just using convert to float option on strip?

Using the 'Convert to float' option on either/both strips doesn't reproduce the problem in this task.

(Commented on #82094 too; I couldn't reproduce that)

>without changing colorspace in rendering panel and just using convert to float option on strip? Using the 'Convert to float' option on either/both strips doesn't reproduce the problem in this task. (Commented on #82094 too; I couldn't reproduce that)

Richard Antalik commented

2021-01-25 04:10:52 +01:00

Can you see this blue area even if you render the image? Can you save rendered image and check saved image?
Can you sample area in preview by clicking onto area with mouse? Does tool also report blue color?

Can you see this blue area even if you render the image? Can you save rendered image and check saved image? Can you sample area in preview by clicking onto area with mouse? Does tool also report blue color?

Corwin Kerr commented

2021-01-25 23:27:19 +01:00

Can you see this blue area even if you render the image? Can you save rendered image and check saved image?

The render looks normal, even on saved image.

Rendering even makes the sequencer preview window look normal until I change the frame. (Caching maybe?)

If I import the saved image back into Blender as an image strip, it looks fine unless I start cropping it.

Can you sample area in preview by clicking onto area with mouse? Does tool also report blue color?

Good idea.
White area shows as expected:
R:1.00000 G:1.00000 B:1.00000 A:1.0000 | CM R:1.0000 G:1.0000 B:1.0000 [white patch] H:0.0000 S:0.0000 V:1.0000 L:1.0000

Blue area shows negative values in the red channel:
R:-1407600499915438018491580416.00000 G:1.00000 B:1.00000 A:1.0000 | CM R:-0.1250 G:1.0000 B:1.0000 [blue patch] H:0.5000 S:1.1250 V:1.0000 L:0.7608

(!)

>Can you see this blue area even if you render the image? Can you save rendered image and check saved image? The render looks normal, even on saved image. Rendering even makes the sequencer preview window look normal until I change the frame. (Caching maybe?) If I import the saved image back into Blender as an image strip, it looks fine unless I start cropping it. >Can you sample area in preview by clicking onto area with mouse? Does tool also report blue color? Good idea. White area shows as expected: `R:1.00000 G:1.00000 B:1.00000 A:1.0000 | CM R:1.0000 G:1.0000 B:1.0000 [white patch] H:0.0000 S:0.0000 V:1.0000 L:1.0000` Blue area shows negative values in the red channel: `R:-1407600499915438018491580416.00000 G:1.00000 B:1.00000 A:1.0000 | CM R:-0.1250 G:1.0000 B:1.0000 [blue patch] H:0.5000 S:1.1250 V:1.0000 L:0.7608` (!)

Ankit Meel commented

2021-04-07 11:18:49 +02:00

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

Richard Antalik commented

2021-04-07 13:12:00 +02:00

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

Richard Antalik commented

2021-04-07 13:12:00 +02:00

Sorry for late answer, I have lost this report. Adding BF-Blender tag so it's in my workboard.

Other than that, Still can't reproduce this issue, But I have noticed R channel having value of -0.000 with Linear colorspace. So there is probably something to this.

@ckerr since this issue doesn't exist during render, can you check if this issue still exists when you switch User Preferences > Viewport > Textures > Image Display Method to GLSL or 2D Texture?

Sorry for late answer, I have lost this report. Adding BF-Blender tag so it's in my workboard. Other than that, Still can't reproduce this issue, But I have noticed R channel having value of -0.000 with Linear colorspace. So there is probably something to this. @ckerr since this issue doesn't exist during render, can you check if this issue still exists when you switch User Preferences > Viewport > Textures > Image Display Method to GLSL or 2D Texture?

Corwin Kerr commented

2021-04-09 07:56:23 +02:00

@iss I found that both GLSL and 2D Texture had no change in behavior.

Blender Version
Broken: version: 2.93.0 Alpha, branch: master, commit date: 2021-04-09 05:00, hash: 3f91591c1d

@iss I found that both GLSL and 2D Texture had no change in behavior. **Blender Version** Broken: version: 2.93.0 Alpha, branch: master, commit date: 2021-04-09 05:00, hash: `3f91591c1d`

Richard Antalik commented

2021-04-21 05:49:02 +02:00

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

Richard Antalik commented

2021-04-21 05:49:02 +02:00

Thanks for update.

I wanted to continue investigation, but now I can't reproduce even negative value in R channel.
No issue on another machine as well.

Issues like this may be caused by imprecise math being done on GPU, so you may try using different GPU driver or even software based openGL emulation to check whether this would resolve the issue. I would expect this to be case only with GLSL though, but I don't have deep knowledge how these methods work internally.

Other than that I am out of ideas.

Thanks for update. I wanted to continue investigation, but now I can't reproduce even negative value in R channel. No issue on another machine as well. Issues like this may be caused by imprecise math being done on GPU, so you may try using different GPU driver or even software based openGL emulation to check whether this would resolve the issue. I would expect this to be case only with GLSL though, but I don't have deep knowledge how these methods work internally. Other than that I am out of ideas.

Omar Emara commented

2022-03-21 13:05:36 +01:00

Added subscriber: @OmarEmaraDev

Omar Emara commented

2022-03-21 13:05:36 +01:00

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

Omar Emara commented

2022-03-21 13:05:36 +01:00

Can you try capturing an API trace of the frame where the issue happen and attach it here? You should remove all other frames if possible. See https://apitrace.github.io/ for instructions.

Corwin Kerr commented

2022-03-26 20:55:56 +01:00

I can no longer reproduce the original bug. (Note this test was on 2.93.0 release)

System Information
Operating system: macOS-10.15.7-x86_64-i386-64bit 64 Bits
Graphics card: AMD Radeon Pro 5500M OpenGL Engine ATI Technologies Inc. 4.1 ATI-3.10.22
Blender Version
Works: version: 3.0.1, branch: master, commit date: 2022-01-25 17:19, hash: dc2d180181
Works: version: 2.93.0, branch: master, commit date: 2021-06-02 11:21, hash: 84da05a8b8

However, there is another problem. I'm not sure if this problem existed when I made the first report, but it seems related.
If I set the "Display Channels" to "Color" instead of "Color and Alpha", places with background showing through look green.

This has a bigger impact when using the Display Mode to view anything besides "Image Preview", such as "Chroma Vectorscope".

Blender Version
Broken: version: 3.0.1, branch: master, commit date: 2022-01-25 17:19, hash: dc2d180181
Broken: version: 2.93.0, branch: master, commit date: 2021-06-02 11:21, hash: 84da05a8b8

I can no longer reproduce the original bug. (Note this test was on 2.93.0 release) **System Information** Operating system: macOS-10.15.7-x86_64-i386-64bit 64 Bits Graphics card: AMD Radeon Pro 5500M OpenGL Engine ATI Technologies Inc. 4.1 ATI-3.10.22 **Blender Version** Works: version: 3.0.1, branch: master, commit date: 2022-01-25 17:19, hash: `dc2d180181` Works: version: 2.93.0, branch: master, commit date: 2021-06-02 11:21, hash: `84da05a8b8` However, there is another problem. I'm not sure if this problem existed when I made the first report, but it seems related. If I set the "Display Channels" to "Color" instead of "Color and Alpha", places with background showing through look green. ![Screen Shot 2022-03-26 at 3.55.10 PM.png](https://archive.blender.org/developer/F12948517/Screen_Shot_2022-03-26_at_3.55.10_PM.png) This has a bigger impact when using the Display Mode to view anything besides "Image Preview", such as "Chroma Vectorscope". ![Screen Shot 2022-03-26 at 3.51.40 PM.png](https://archive.blender.org/developer/F12948515/Screen_Shot_2022-03-26_at_3.51.40_PM.png) **Blender Version** Broken: version: 3.0.1, branch: master, commit date: 2022-01-25 17:19, hash: `dc2d180181` Broken: version: 2.93.0, branch: master, commit date: 2021-06-02 11:21, hash: `84da05a8b8`

Omar Emara commented

2022-03-26 21:20:38 +01:00

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

Omar Emara commented

2022-04-04 16:44:04 +02:00

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

Omar Emara closed this issue

2022-04-04 16:44:04 +02:00

Omar Emara commented

2022-04-04 16:44:04 +02:00

It would be best if you open a separate report for other issues. Since you can't replicate the original issue, we will archive this for now.

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Blue on cropped part of image when Sequencer color space is Linear #85003