Preventing core burnout

[astrodoc71]

I'm currently processing M13 and have the problem of core burning out during histogram stretch when trying to bring out the peripheral areas of the cluster. I tried a range selection mask, inverting it and adjusting the lower limit until only the core was visible but it seems to produce weird central contrast artifacts (at least in preview mode) as I try to stretch the outer portions. Perhaps this is not the correct approach to this?
Dave

[Philip de Louraille]

In a word: masks.
I am not expert enough with them and their uses to remember how to use them without looking at tutorials.
There ought to be some explanations here: http://pixinsight.com/tutorials/index.html

[georg.viehoever]

.... I tried a range selection mask, inverting it and adjusting the lower limit until only the core was visible but it seems to produce weird central contrast artifacts (at least in preview mode) as I try to stretch the outer portions....

This may be an artifact of STF (limited accuracy). Did you try a real HistogramTransform?
Georg

[astrodoc71]

Yes, real histogram transform only. No STF

[astrodoc71]

In a word: masks.
I am not expert enough with them and their uses to remember how to use them without looking at tutorials.
There ought to be some explanations here: http://pixinsight.com/tutorials/index.html

Thanks for the reference. It does appear that the tutorial "dynamic range and local contrast" provides some clues as to how to deal with this.