[gregbradley]

I thought I would start a thread where we can discuss different techniques for data rejection. This will help anyones image processing and its an area that does not seem to be well written up.

I usually only use hot and cold pixel rejection in CCDstack.

It used to be one item in CCDstack 1 but in CCDStack 2 it is 2 separate items. Also hot pixel rejection in CCDstack 2 seems to bog as the slider colours in and then it does nothing apparently for quite a while then it completes its task, so watch for that.

Once its done its selection I then use interpolate the rejected data to correct it.

I have found in experimenting that if I did not do hot/cold pixel rejection I would tend to get little black spots or coloured spots in the background of the image that required the healing tool to correct. Doing this I now rarely have to correct spots in the background.

However the other data rejection tools seem to damage the image when I have used them or select way too much of the image. Obviously the default settings are not right and have to be adjusted. To what I don't know.

I don't see they are of much use to my setup where the images are usually defect free except for satellites etc.

I use median combine. I notice John Gleason said to use sigma reject combine. I don't think that is an option in CCDstack. He must be using another program.

Greg.