Help with removing a dark spot

pfile said:

m45masks.zip

drive.google.com drive.google.com

that is a zipfile with some process icons, the masks and the fixed image.

what i did was to first draw a preview over the bottom right spot, with the edges of the square touching the edges of the circle. that way i didn't have to eyeball it in game - i just used the preview origin and size to figure out what to put into GAME. then i generated a binary mask with GAME and used AtrousWavelets to smooth the edges of the mask a bit. then i applied $T*1.16 to the image thru the mask. not perfect but close enough for government work.

then i cloned the mask and rotated it 180 degrees, masked the image with that mask and again thru trial and error came up with $T*1.1 to fix that spot. this only worked because your image was apparently not cropped, or it was cropped with the same amount of pixels chopped off from all the edges so that the dust spot on the other side was exactly in the same place, but rotated.

rob
Click to expand...

WOW!!! I am impressed. That is amazing! I am not sure I will be able to figure out how to do it on my own but I am going to try to work with it and see if I can. I am so new to using Pixinsight and new to imaging. Working with masks and doing what you did seems to have a long learning curve.

My camera ASI2600 color, is brand new and all of my images have that circle. I just looked at the sensor on the camera, telescope, etc and I cannot see anything that would make that circle. I am beginning to wonder if there is a defect with the camera.

I really appreciate you taking your valuable time to do this. It is very thoughtful of you and I hope one day I will be able to do the same for somebody.
 
pay it forward yeah

there must be a reducer or other optical element just ahead of the camera sensor? that spot is definitely from a fleck of dust. it's so out of focus that it casts a circular shadow. you can actually calculate how far a piece of dust must be from the sensor with the formula on this page:


the dust itself could be pretty tiny, just a mm or two. sometimes they are hard to see with your eye unless you get the lighting just right.

keeping the optical path clean is best but dust motes are just a fact of life so eventually you end up in this situation. flats should take care of the spots but of course if the dust moves between the flats and lights, you're out of luck.

rob
 
pfile said:
pay it forward yeah

there must be a reducer or other optical element just ahead of the camera sensor? that spot is definitely from a fleck of dust. it's so out of focus that it casts a circular shadow. you can actually calculate how far a piece of dust must be from the sensor with the formula on this page:


the dust itself could be pretty tiny, just a mm or two. sometimes they are hard to see with your eye unless you get the lighting just right.

keeping the optical path clean is best but dust motes are just a fact of life so eventually you end up in this situation. flats should take care of the spots but of course if the dust moves between the flats and lights, you're out of luck.

rob
Click to expand...

I took that apart also but just can't find it. I will try again.
 
Geoff said:
No idea what it is, but since it seems to be circular and uniformly dark it should be easy to make a mask which blocks out everything except the spot, using either PixelMath or the Game script. Then use Curves to lighten it to match the rest of the image
Click to expand...
Geoff, if doing this, do you recommend doing it while the image is linear or after it's been stretched.
 
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