I took some photos at night and I didn't have long exposure noise reduction on. My photo has quite a few hot pixels, here's a 100% crop of a part of the sky:
Since long exposure noise reduction is sometimes called "dark frame subtraction", I naively thought I could just subtract a dark frame from the image by loading it in another layer in Photoshop (or Affinity Photo in my case) and setting its blend mode to "Subtract". But of course that just converts the hot pixels into black pixels:
So I guess I somehow have to overwrite the pixels' channel values with those of the adjacent pixels, proportional to the value in the dark frame. What is a good software/procedure to achieve that?