Can you tell me

[speach]

Can you tell me what these are and how they get on my pixs? They appear no all my pre-processed pix not always this shape more often a series running left to right and top to bottom through approx. 30 lines of pixels. They will be randomly spaced through-out the pix but always the three colours RBG. They do not appear on the originals only on the pre processed pix. I'm finding it quite puzzling, but I can get rid of them by using the clone tool but that take a lot of time.
     

[RobD]

They look like hot pixels that have not been removed by darks or cosmetic correction.
The pattern will depend on the movement between frames either caused by dither or drift.

If they are hot pixels I would expect them to be in approximately the same place on all stacked images, exact location will depend on drift/dither.
Having said that again if they are hot pixels they should show in the original image, but only as a single pixel which will be in the same place on each frame. Star alignment and stacking then gives the pattern. I would have expected that anything left by darks and cosmetic correction would then have been removed by 'rejection' in the stacking routines.

Rob

[oldwexi]

Hi Speach!
These are hot Pixels which have not been removed.
Usually when stacking them they disappear if you select !Pixel Rejection!.
If you have selected Pixel Rejection than it could be tha the Parameter are to high
so they got not clipped.

Gerald

[RobD]

Gerald,
looks like you are having one of my ' senior moments',    I was replying to 'Speach's question.

Rob

[Alejandro Tombolini]

As Gerald and Rob said you have to set a value of Sigma high in Image Integration tool that effectively remove the hot pixels.

See this video that shows how different values of Sigma high remove hot pixels when using Winsorized Sigma Clipping as Rejection algorithm.
Also you may want to inspect your rejection maps and see there if those pixels have been effectively removed.

Saludos, Alejandro.

[oldwexi]

Rob!
Yes, you are right, thanks for the nice expression "Senior Moment".
Yes, i wanted to reply to Speach´s question.
Sorry for adressing the reply not correct.
Gerald

[speach]

Thank-you Gents. I'm only very new at A/P with starting to learn that, and starting to use PI it's a very steep learning curve indeed. Your answers have given me something to work on. Thank you again.

[speach]

Yes it was hot pixels, got them under control now with a bit of fiddling in the setting.

[Warhen]

Speach, CosmeticCorrection is fabulous for this. Run it after Calibration and before Alignment, or automatically with the BatchPreprocessing script. You must set up the template beforehand. I like to use Auto Detect for hot pixels, and also a master dark at an appropriate setting, and I also make detailed Defect Lists for bad columns. Hot pixels are nonlinear, and often escape the dark frame. CC will average in the values of surrounding pixels. Dithering is also critical when guiding! If they escape calibration, alignment drags the single pixel out to many. Good luck!