PixInsight Resources

MaskedStretch and Stars Cores

by Alejandro Tombolini

Processing

When applying MaskedStretch tool, cores of saturated stars will be protected and will remain as they are, independently of the increasing bright in the periphery. A possible alternative to solve this is repair the stars cores before stretching. The following image of Antares will be useful to show the reparation.

First I have applied MaskedStretch tool to a crop of the image with Antares using the default values. As expected the center of the star does not look fine.

Over a clone of the linear image apply the Repaired HSV Separation script. Set the desired levels to Clip Shadows and Repair level and check V- no repairs for the scrip to generate also the Unrepaired V.

You will get four new images:

• Unrepaired V
• V
• Sv
• H

I have seen in some cases that is better to generate the new image using the Unrepaired V instead of V. Using ChannelCombination tool generate the new image.

The center of the stars look better now in the linear image:

Finally apply the same Masked stretch process to the repaired image.

See Bob Andersson post about Repaired HSV Separation Script.