I have an NVIDIA GPU with its corresponding drivers, and I want to ensure that the image displayed on the screen precisely matches the original intended image, saved as an npy object. However, I noticed that certain pixels have slightly different values (difference of either +1 or -1) in random color channels and locations compared to the original image. After disabling dithering using the NVIDIA control panel, I managed to reduce the number of different pixel values by 75%. Nevertheless, there are still occasional differences of exactly 1 (definitely not noticeable by the human eye) in approximately 2%-7% of the image pixels. I explored a little bit further and I found that these variations are not random but rather tend to occur mainly in areas with changes in depth.
What might be the cause for these discrepancies? It appears that despite disabling dithering through the NVIDIA control panel, some dithering algorithms might still be active, contributing to the remaining differences in pixel values.