narrow band colors

[vernon tucker]

hello  can anyone tell me if there is a method to simulate narrowband colors if i do not have the filters  thanks

[Philip de Louraille]

None that I am aware of.
Narrowband filters only capture a tiny part of the electromagnetic spectrum, each filter being designed to capture a physical effect, such as an electron of an atom of hydrogen coming from the third orbital to the second.

Normal color filters capture a much wider range of the electromagnetic spectrum and there is no method I know that can extract the narrowband info (which was captured) into the "largerband" data as it is mixed in with other data.
 
For instance, the red filter will capture "100" photons in a pixel. A narrow band would have captured "5" of a particular energy. Which 95 photons would you remove? The data is here there somewhere but has been mixed in and is now unretrievable.

[Geoff]

I don't think the poster wants to extract true narrowband data from his RGB filters. I think he is asking if you can fake narrowband colours with the RGB data so that it looks like a typical narrowband image.  I have no idea of how to do this.

[oldwexi]

Hi Vernon Tucker!
As Philip already mentioned, i think there is no way to get narrowbanddata out of an final RGB image.

If you want to create an fake Hubble Palette image out of an RGB you could use
PixelMath to recombine the data. PixelMath allows nearly everything...
Find attached a link to a PI-Processing screenshot using an old NGC6914 image i have with the original RGB data
faked with PixelMath to what i think could be a faked Hubble Palette.
The SII  i created by using a curve over a copy of the the R Channel.
http://www.werbeagentur.org/oldwexi/fotos/FalseColorRGB%20.jpg

So, if thats what you want somehow - PixelMath could be a help.

Aloha
Gerald