Multi channels images

[StasV]

I want to combine in one image more than 3 channels (For example L, R, G, B, Ha, Ha-continuum) and make operations ones for all channels.
It seems me very comfortable for operations such as Crop, DBE and mosaic star alignment
As I understand, PI provide only one way for it: Use alpha channels. Am I right?

I found some problems
1 ScreenTransferFunction works only with 3 channels
2 DBE is works only with 3 (RGB) channels

Is it possible in PI to work with multi channels images, like I want?
May be .... Do You no another way?

[Philip de Louraille]

You want to use PixelMath for this operation.
I am not sure what you mean with "... and make operations ones for all channels."
In PixelMath, use all 3 RGB channels (unselect use a single RGB/K...)
Say your frames are called L, R, G, B, Ha, and Hac.
In the R field, you could have something like
 0.6 * ( 1.05 * Ha - 0.05 * R) + 0.4 * ( R - Ha )   *** (note that the weights 0.6 and 0.4 add up to 1.0. You will want each other color channel to have the same weight. The above algorithm is a combo of this thread  http://pixinsight.com/forum/index.php?topic=2545.new;topicseen#new

Or you can put other stuff if you wish to combine L and Hac as well.
Then you still have the G and B channel to play with.

[StasV]

Sorry,  “combine” is not correct word. May be “collect” is better.
I do not speak about LRGB or HaRGB combination or Continuum subtraction.

Idea is:
Some of operations is a very similar for each channels. For example. Crop is absolutely similar for R G B Ha L OIII etc. channels of one image. DBE is similar.
If I apply DBE for RGB image, I get 3 simple DBEs for each channel automatically. I do not need to apply DBE 3 times separately for R G B.
Why not ….  expand this operation for more than 3 channels ?

[Philip de Louraille]

I see what you mean but not all operations are color channel independent. If you are working on a RGB shot (and by that I mean "natural color"), then doing a DBE on all 3 channels independently will not give the same result as doing a DBE on a RGB frame. Ditto for a HistogramTransformation of a natural RGB frame.
Now, if your frames are narrowbands, that is a different situation.

But back to your question, PI is a scripted language. There is no reason why you could not write a script which would go through a folder and apply a single operation (or more probably) such as Crop or DBE to all images contained within.
Is this what you are referring to or would you like all images to be opened on PI desktop and somehow "link" several of them (1 to many being more than 3) and then apply a PI operation on that symbolic link so that all such images then get operated on?

[Carlos Milovic]

Hi Stas
There are some processes that work on every channel, independly. Internally, this is defined by routines that look for the "number of channels". Others, just ignore Alpha channels, since they look for the "number of nominal channels" (that depends on the color space... RGB = 3, Gray = 1).
Anyway, you may use Process Icons as a workaround. Just encapsule the process, and then reuse all the parameters on other images. If it is not a dynamic process (some of them will work too), you may use Image Containers to speed up the process and automatize everything.

[StasV]

Thanks for answers!