[pmrid (Peter)]

Here is a crop from an stacked image. You will see immediately the repeated pattern of red, green, blue color blocks - identical blocks.

These will almost certainly be the product of dithering and something I would expect Sigma Clipping would pick up and remove. But in APP, this is not happening and so far, I haven't found a reason/solution.

Stacking in DSS does the job nicely but not APP.

Anyone??