Window-sill Trapezium dehaloed

As I have previously posted, I have been trawling through my archive looking for likely candidates for the “dehalo” processing i came up with to get rid of those irritating dark haloes around bright objects the PD camera sometimes produces. (I think it is probably an artifact of the PD’s compression/noise reduction algorithms). Again, I’ve already posted some of these. M42 seems particularly to benefit from this:

Digital Astronomy – things to do when it is cloudy!


However, I found this one too, that I was particularly taken by. Here is the original and the dehaloed version.

It is quite simple and quick to do in GIMP and I’ll post the method if anyone is interested, but I suspect it is just my kit and methodology that creates the issue. “Proper” imagers don’t seem to get the problem!


4 Responses

  1. I do very little, if any, sharpening with DSOs. The haloes do get more pronounced when you adjust “curves” though. There were lots of example images on this web-site:
    They now seem to have vanished, but there is one still there where the haloes a very apparent.
    I think it is probably to do with the camera’s internal software, either sharpening or noise reduction. It was only £100-ish after all (what do you want, blood?!).
    However, I think the dehaloing method is quite effective.

  2. So do the haloes appear in the image before you’ve processed Roger? I know sharpening can often introduce them, but I’ve not had them direct from the camera. I wonder if this means your PD camera does some sharpening internally.

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