While working on processing the Trifid Nebula in PixInsight I came up with a new pixel mapping function.
It is a mathematical function based on a dampened sine wave which only maps pixels in the shadow and mid tone range.
I tried it out on a luminance image of the Lagoon Nebula and the results look encouraging. Compared to an unmapped image its looks like a much deeper exposure without the star bloat and excessive noise if the image were simply over stretched.
The unmapped image is here.
http://members.iinet.net.au/~sjastro/lagoonHaNormal.jpg
The mapped image is here.
http://members.iinet.net.au/~sjastro..._Pixelmath.jpg
Regards
Steven