Colour processing

[Sully]

Another member has kindly sent me some Subs, Ha, O111 and S11 files, so that i can practice my processing before entering the realms of DSO AP myself. As I dont want to badger the man with queries, very basic questions no doubt, I thought I'd ask you guys for some help.

I've stacked the relative Ha, O111 and S11 files, converted them to 16 bit, but when I load up the Stacked images they seem to be in mono, how do i get them into colour? Do I have to combine them somehow? I've seen the finished product in colour just cant figure out how to do it.

Any advice more than welcome

Sully

[Ags]

They are narrowband so they are all mono. The Ha and SII are both deep red, so you would not want them in their 'true' color.

The idea is you assign red, green and blue to the three files and then blend them in your image processing software to get a false color image.

Assuming you are using GIMP or Photoshop, you would put all three images in separate layers and then edit each layer to be blue, green or red.

[Sully]

Does each band have to be a certain colour?

[steppenwolf]

Using Photoshop, load all three images, select 'Channels' then select the little drop-down menu at top right and choose 'Merge Channels'. Change the option to 'RGB colour' and you will be asked to choose which of your three files should be mapped to which colour. The most usual choice here is the Hubble Palette so map SII to Red, Ha to Green and OIII to blue. This will give you your start image which will be predominantly green as the Ha (now mapped to green will almost certainly be the strongest data set) - remember though that this will be a totally false colour image.

Have a look at this excellent website for more information on this technique for producing false colour images.