image artifacts - analysis please

[rcheshire]

Maybe this request could be in the beginners section, but it's a bit techo.

3 images cropped from the same frame (M8: 1 x 5 minutes and 1 x 6 minutes) calibrated with a master dark and master bias in Pixinsight - no flats (still working on producing a reliable set).

The original image was colour calibrated and background neutralised in Pixinsight.

I've boxed the areas in question, and other than obvious alignment issues, there are;

1. dark pixels adjacent to the brighter stars,
2. in the small image there is a block of red pixels, and on the left a single bluish pixel.
3. what appears to be either cloud or reflection nebula producing a bluish tinge...

I'm not sure that these issues/artifacts would show up with more data (possibly), but conveniently they show up here - :question:

Many thanks

Rowland.

[multiweb]

1_ It happens sometime on undersampled images when you debayer direct to color. The cure is to debayer to each channel, stack then recombine.

2_ red block is likely to be a bunch of hot pixels. You can do darks to get rid of that or median combine opposed to mean combine or just heal them out on PS.

3_ Hard to tell. Could well be part of the data.

[higginsdj]

Thosee black spots are either dead pixels or the dark doesn't match the light image. It is also possible that you have over stretched the light image.

[rcheshire]

Thanks both... always appreciated:)