PixInsight Forum (historical)

PixInsight => Tutorials and Processing Examples => Topic started by: sonshadowcat on 2019 November 20 09:24:27

Title: Linearfit giving curious result
Post by: sonshadowcat on 2019 November 20 09:24:27

I'm just a beginner PI user so bear with me if this is a dumb question 😀.

I'm trying to use linearfit to match my hydrogen and sulfur images to my oxygen (oxygen is brighter by far due to light pollution and broader filter). When I apply it, however, the images go almost entirely white.

Am I not supposed to use the oxygen as the reference image even though the histogram for it is clearly more tilted towards the right than any other image? Or is there a workaround I am not aware of?

Title: Re: Linearfit giving curious result
Post by: pfile on 2019 November 20 10:21:19

recompute the STF for the image that you ran LF on. LF changes the brigtness of the image and the old STF is now too aggressive for the new data.

rob

Title: Re: Linearfit giving curious result
Post by: sonshadowcat on 2019 November 20 10:24:22

I did. The stretched image is nearly entirely white.

Title: Re: Linearfit giving curious result
Post by: pfile on 2019 November 20 10:44:09

did you use linearfit on a stretched image?

try turning off the STF entirely...

rib

Title: Re: Linearfit giving curious result
Post by: sonshadowcat on 2019 November 20 10:50:47

I did not auto an already stretched image. I made sure that the stf was off entirely before I reapplied. I'll have to post some images when I get home to show what's going on.

Title: Re: Linearfit giving curious result
Post by: astroedo on 2019 November 20 12:17:49

Are the images already aligned?
LF must be used only on aligned images, both at linear stage.