Problem summary
Color banding can occur in Unprojections
Customer reported version
Mari n/a
Customer reported platform
Windows
Steps to reproduce
1) Download the attached PNG and OBJ files
2) Create a project using the attached Plane.obj
3) Create an 8-bit Channel and import the downloaded image
4) View the Current Channel
5) Switch to the UV view
6) Transform the Paint Buffer to roughly match up with the Patch
7) Create a Projector -
8) In the Unprojection settings, set Shader Used to Current Channel, Lighting Mode to Flat and Color Depth to 8bit
9) Unproject the image to a PNG file
10) Export the Channel Flattened as a PNG file
11) View the Unprojected, exported and source images in Mari's Image Manager or with an external image viewing program, and compare the banding in the images
Expected behaviour
The Unprojected image should have a similar level of banding as the exported image.
Actual behaviour
The Unprojected image has more banding compared to the exported/source images, which is most noticeable in the darker values in this example:
Shown below with the brightness increased to make the banding more visible:
Workaround
Banding can be prevented if you unproject to a higher bit-depth i.e. 16 or 32-bit.
Reproduced by support
This bug has been reproduced in:
Mari 5.0v3 - Windows 10 - CentOS 7.9
Mari 4.8v3 - Windows 10
Mari 4.7v1 - Windwos 10
Mari 4.5v2 - Windows 10
Mari 3.0v1 - Windows 10 - CentOS 7.9
Earliest version tested
Mari 3.0v1 - This issue appears to be in all tested versions of the product
