First LRGB Effort

[Pomerol]

Acquired an old HX916 recently and after 5 years of dslr processing in PS have been trying to learn how to manage LRGB.

I am using AstroArt for image capture, calibrating subs in DSS and then basically using the Wade-Observatory tutorial for the RGB and LRGB actions.

The problem that I haven't fixed yet is that after combining the RGB I have a slight misalingment of the images (no problem with aligning the L with the RGB).I can't see a way to fix this in PS, I have tried the AstroArt Trichromy but don't really understand what this is doing.

Any advice much appreciated.

[Freddie]

When calibrating your subs in DSS use the same frame each time as a reference to ensure everything is properly aligned together. When your reference frame is not one you want in a stack (eg if your reference is a lum when you are stacking red) just make sure it is not ticked. Everything should then be perfectly aligned when you import into PS.

[Pomerol]

Freddie, many thanks, just tried it....a big improvement.

Rgds

Ian S.

[Pomerol]

Freddie, just went through the whole process again using the "reference frame method" and I still have an alignment problem.

The red and green are lined up but the blue is out of line on the RGB.

I am using 2x2 bin and have noticed the blue image size is 2 pixels bigger than the red and green (653 v 651) which is probable what is causing the misalignment.Have tried changing image sizes on R/G/B and RGB but cannot get good alignmant.

Rgds

Ian S.

[Pomerol]

As normal there is a way around the problem.I found that by selecting the blue channel only (in the rgb) I could apply the move tool and move the blue till it lined up with the red and green.

Still don't know why the blue was bigger than the red and green though?

[ollypenrice]

AA5 is not good at aligning colour layers. It often gets it wrong for me. (You open Trichromy, put the red in the red, the blue in the blue etc and click auto align. But it doesn't work!!)

I align my colours in Registar but that's a quite costly programme which I use for other jobs as well.

To align your colours in AA5 you can use the longhand method.

Open your reference image, say Red.

Open View and then Stars.

Click on three well separated stars in a tirangle across the image. Smaller ones are best but be sure you can see them in all three colours.

Open the green image. As above, View, Stars, and click the same three stars in the same order. Then Image, and Co -Register. Save the new green as, for example, Green CR.

Repeat for Blue.

Now in Trichromy the Red, Green CR and Blue CR should be aligned without checking the Align box.

Hope it works.

Olly

[Pomerol]

Olly, thanks for your input.

Used the "longhand" method and did the co-registration OK.

The alignment after Trichromy looked good but the image I ended up with looked nothing like I had got using Photoshop sot think I will stick with that for the future.

Rgds

Ian S.