What causes this ?

[star gazer]

Does anyone know what causes this when I process my images?



This is my workflow:

1. convert CR2 to Fits
2. Create master dark
3. Image calibration
4. Debayer
5. Star alignment
6 image integration

The image is the result of step 6 without doing anything else in PI and is a 2:1 crop before STF or any stretching takes place

[georg.viehoever]

UFOs? 

Check on your original image files if you see something like this in them. Unlikely that Calibration and Integration cause such artifacts without them being somewhere in your base data.
Georg

[Philip de Louraille]

Look at each image separately and do a ScreenTransferFunction on each. Those details are bound to show up.

[star gazer]

Hi Guys,

I don't see them in any images until the final integration. At least if they are there, they are too subtle for me to see. They do seem to be worse were I combine images from separate imaging sessions i.e. where the orientation of the camera is very different between the sessions.

V strange.

[georg.viehoever]

I know of nothing in ImageIntegration that could possibly cause such artefacts. II is basically a weighted addition of the source images, and therefore your "UFOs" most likely are also in the source images.
Georg

[Raymond]

It's probably the wrong guess, but maybe it can have sth. do to with atmospheric dispersion (the stars should have red/blue borders). Try to extract the R, G and B channel using Channel Extraction. Allign the three images and combine them again.

[Cleon_Wells]

What do the High and Low pixel Rejection images look like, what's your setup?
Cleon
PS I've got a history of imaging UFOs and have never seen anything like this.

[martin_magnan]

Hi

In step 5. Star Alignment

make sure the Pixel Interpolation is set to "Bicubic Spline" and not to Auto. The Auto use Lanczos and it does funny stuff around remaining hot pixels and small stars.

Martin