Back to forums

PixInsight - How do I overlay a luminance layer from a mono cam onto RGB from a color cam?

Processing Deep Sky M101 Messier Objects
7 replies•194 views
JohnAdastra avatar
JohnAdastra avatar
Hello PixInsight Users!

I just start working with a newly acquired ASI2600MM-P camera and got some nice luminance data on the M101 galaxy. I also have data from an ASI071MC color cam. While both were taken with the same C925Edge HD telescope, the arcsec/pixel ratio is different and the mono data is binned at 2X2, versus color data at 1X1. 

When I try to overlay the processed mono L layer over the RGB image, PixInsight keeps telling me "incompatible geometry". I have tried as L in LRGB Combination, and various PixelMath combinations but nothing is working. I can do a StarAlignment using Views and drag the one on top of the other in the workspace and they match up.  But that is as far as I can get.

I have never tried combining data from two different cams before. Any suggestions would be appreciated.

Thanks,

John
Well Written Respectful Engaging
Geoff avatar
Geoff avatar
Just guessing here, but it could caused by the number of pixels of the RGB and the L images being different–try resampling the RGB to have the same dimensions in pixels as the L.
Geoff
JohnAdastra avatar
JohnAdastra avatar
Thanks Geoff. I  suppose I could resample the mono at 1X1, but the arc/pix would be 0.47, a bit oversampled and would be a tad blurry. Can't rebin the color to 2x2 as I would lose the RGB matrix. Trying to work with the data already collected.

Best Regards,

John
Well Written Respectful
Min Xie avatar
Min Xie avatar
I would suggest doing the following:

- Use StarAlignment process on RGB master, use the Mono L as reference.
- Use LRGBCombination, uncheck RGB, assign L to your Lum master from 6200mm. Apply to the registered RGB master.

Hope it helps.
-Min
Helpful
JohnAdastra avatar
JohnAdastra avatar
Min,

Just tried that and I think it may work. When I did this the first time I had the RGB added as a View in the Target Images of StarAlignment, which would not allow me to complete the overlay later.  When I use nothing in the Target Views fields and the mono as Reference that stops the error from occurring later. Now I can try to process to completion.

Many thanks!

John
Tayson avatar
Tayson avatar
Always align r, and b to g.
remember to check in star alignment distorsion correction.
Bogdan Borz avatar
Bogdan Borz avatar
Hello PixInsight Users!

I just start working with a newly acquired ASI2600MM-P camera and got some nice luminance data on the M101 galaxy. I also have data from an ASI071MC color cam. While both were taken with the same C925Edge HD telescope, the arcsec/pixel ratio is different and the mono data is binned at 2X2, versus color data at 1X1. 

When I try to overlay the processed mono L layer over the RGB image, PixInsight keeps telling me "incompatible geometry". I have tried as L in LRGB Combination, and various PixelMath combinations but nothing is working. I can do a StarAlignment using Views and drag the one on top of the other in the workspace and they match up.  But that is as far as I can get.

I have never tried combining data from two different cams before. Any suggestions would be appreciated.

Thanks,

John

Hi John

Pixinsight can't combine images that have different sizes and resolutions (which is the case for your 2 masters from 2 different cameras). Just register (star align) on the smaller image and then you can combine them. If you register on the smaller size image, you don't have to crop at the end the masters, there will be no black excedentary background.

CS,

Bogdan
Helpful Concise
JohnAdastra avatar
JohnAdastra avatar
Thanks for the tip, Bogdan. This is new territory for me.

Regards,

John
Well Written Respectful