Adding extra pixels on left or right of image source containing a dithered image adds banding.

[sonneveld]

With an image that contains dithering, if the scaler includes extra pixels on left or right, you can see noticeable banding. This is with with default shader and no extra scaling. Does this suggest that scaling occurs somewhere when adding extra pixels?

When taking screenshots, I did notice that taking screenshots of the source (instead of the scene) lead to screenshots with the same dimensions of 640x400, even though OBS says that it is 660x400 in the transform window after adding extra pixels.

Using OBS 29.1.3 and obs-shaderfilter 2.2.2 on Windows 10 (haven't had a chance to upgrade to newer OBS yet sorry, hopefully it's unrelated)

To test:
Add this image as a source with no scaling:

Configure shader with extra pixels on left and right as so:

OBS scene screenshot without shader:

OBS scene screenshot with shader:

[sonneveld]

I did some experimenting and I've noticed that I don't get the same banding effect issue if I use a separate "Crop/Pad" filter before the shader filter. So there may be some differences in the implementation of "Crop/Pad" 's padding and shaderfilter's.