I'm trying to render my models as pixle perfect sprties for a game. I'm rendering with a clear background using the transparent film setting, then adding a solid color (RGB 0,0,255) as the background with compositing nodes : Render Layers -> Alpha Over -> Composite. The 3d models render correctly, my problem is the background is not a solid color, but has some shading or variation across the image, which messes up the background for my sprites.
In the picture, I've imported the render into paint.net and used the magic wand tool with a low tolerance (4%) to select the soild blue background, and it selects this bizzar pattern. I can select multiple "strips" across the width of the image that all have this repeating pattern. The color picker tool only returns RGB 0,0,255 and 1,1,255 thoughout the image.
And I can't just use the paint bucket tool to make it all one color, because it won't get the pixles in between my models ;-)
Eevee and Cycles give the same result, exporting the render as different image formats give the same result. I've tried changing the lighting, this does nothing which makes sence because it should be applied after rendering out the models.
Does anyone know what is causing the background of my render to have this slight difference in color? It seems like all the pixles in the background should get set to the same value using this method.