Image compression. Noise in black areas of render. #86112

New Issue

Pablo · 2021-03-01T02:04:33+01:00

Pablo commented

2021-03-01 02:04:33 +01:00

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: GeForce RTX 2080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 461.40

Blender Version
Broken: version: 2.92.0 Release Candidate, branch: master, commit date: 2021-02-19 18:02, hash: b1142858d4
All versions.

Output 8bit images contain noise in the black background areas. Default color management settings, Filmic, exposure 0, Gamma 1.0. I've know of this issue for a number of years.
The issue only seems to apply to 8bit outputs. The attached image shows the exposed black level in Photoshop.

To reproduce:
render an empty scene with black background
save to 8 bit png or jpg file
open in image editor to inspect

**System Information** Operating system: Windows-10-10.0.19041-SP0 64 Bits Graphics card: GeForce RTX 2080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 461.40 ![test2.jpg](https://archive.blender.org/developer/F9854126/test2.jpg) **Blender Version** Broken: version: 2.92.0 Release Candidate, branch: master, commit date: 2021-02-19 18:02, hash: `b1142858d4` All versions. Output 8bit images contain noise in the black background areas. Default color management settings, Filmic, exposure 0, Gamma 1.0. I've know of this issue for a number of years. The issue only seems to apply to 8bit outputs. The attached image shows the exposed black level in Photoshop. To reproduce: render an empty scene with black background save to 8 bit png or jpg file open in image editor to inspect

Pablo commented

2021-03-01 02:04:33 +01:00

Added subscriber: @OtherRealms

Falk David commented

2021-03-01 10:30:42 +01:00

Added subscriber: @filedescriptor

Falk David commented

2021-03-01 10:30:42 +01:00

I don't think this is a bug. When you use the 8bit JPEG compressed image format, you are limited to 256 shades of grey. That's just how it is. If you want more color information (especially for dark images), you should use a higher bit depth. You could also use an uncompressed format like PNG which will give you fewer repeating patches and more uniform noise.

Pablo commented

2021-03-01 12:39:19 +01:00

Hi.
Surely values of 0,0,0 should just produce black though?
I work with large scale LED displays that only deal with an 8bit source, an rgb value of 1 in any channel is clearly visible. I've been flooring the black level in editing software and playing back as 8bit h264/h265. When using doing so in other software, a zero value will effectively mean off. However if I'm not careful a video will slip through that hasn't been floored, since its not visible and hard to detect, anything produced in Blender will result in flickering. I could output 16bit png's in all cases ( I do 50% of cases usually depending on efficiency, some diplays have extreme specs) but was thinking that there must something up on Blenders end. Here's a comparison of 8bit PNG's output and exposed from Cinema 4D and Blender.

Hi. Surely values of 0,0,0 should just produce black though? I work with large scale LED displays that only deal with an 8bit source, an rgb value of 1 in any channel is clearly visible. I've been flooring the black level in editing software and playing back as 8bit h264/h265. When using doing so in other software, a zero value will effectively mean off. However if I'm not careful a video will slip through that hasn't been floored, since its not visible and hard to detect, anything produced in Blender will result in flickering. I could output 16bit png's in all cases ( I do 50% of cases usually depending on efficiency, some diplays have extreme specs) but was thinking that there must something up on Blenders end. Here's a comparison of 8bit PNG's output and exposed from Cinema 4D and Blender. ![Blender.png](https://archive.blender.org/developer/F9856196/Blender.png) ![C4d.png](https://archive.blender.org/developer/F9856198/C4d.png)

Falk David commented

2021-03-01 12:59:11 +01:00

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

Falk David closed this issue

2021-03-01 12:59:11 +01:00

Falk David commented

2021-03-01 12:59:11 +01:00

I also saw the noise when saving out the image. Per default, Blender applies some dithering as a post-processing step.
If you turn that down to 0.0, you get the expected result.

Closing this, as it seems to be the expected behavior.

I also saw the noise when saving out the image. Per default, Blender applies some [dithering](https://docs.blender.org/manual/en/latest/render/output/properties/post_processing.html) as a post-processing step. If you turn that down to 0.0, you get the expected result. ![image.png](https://archive.blender.org/developer/F9856376/image.png) Closing this, as it seems to be the expected behavior.

Pablo commented

2021-03-02 03:11:39 +01:00

Ah yes makes sense, cheers.

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Image compression. Noise in black areas of render. #86112