Based on a recent conversation with a user: It is possible to create diffraction spikes without scripting:
- obtain a nice spike image from some source - in this case I used one of the James-Webb-Telescope images published yesterday
- cut out the spike, edit it to remove stars you don't want to have, and adjust its brightness so background pixels are black (value 0,0,0). I used GIMP for that. No need to mess with transparency or other special features, just make the background really dark.
- Import the spike picture and your target picture to PI. Do SampleFormatConversion to 32 bit float if necessary.
- Apply the spike picture via the Convolution process to your target picture.
- Screenshot of result is below
- You may want to play with mixing the original image with the convolved image, or do histogram transforms first, or limit application to bright stars. (via StarMask), ... I will leave those details to you.
- I am totally aware that this procedure is not what the documentary school of astrophotography likes - see discussions above.
Georg
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