Processing Narrowband Images

[jnc71106]

first off appologies if this has been answered before many many many times

software im using is artemis to capture, nebulosity to calibrate and stack and PS for post processing

im a bit lost when it comes to processing HA/OIII/SII images. if i have captured subs with all 3 filters and then calibrated and stacked each set of subs for HA OIII and SII in nebulosity so that i then end up with 3 files one for each of the filters

do these fits files need aligning with each other as well ?

if so how would that be done without stacking them again as i assume i want to keep them seperate for when i load them into PS to start my post processing as i can then asign each one to a certain colour

or am i wrong in thinking that is how its done. i have watched tutorials on this and they all load the HA image first in PS and then paste the OIII and SII on top of the HA

if you can help me please as i have info overload at the mo

[Freddie]

Yes, you can either align them in neb by using the same alignment star on each set of images or if they are not aligned when you put them in PS you can align each by using the move function. Getting them aligned whilst in Neb is probably best though.

[steppenwolf]

When you align the three filter sets with one another, be sure to use two alignment stars preferably as far away from one another as possible. This action will remove any rotation effects if there are any between the capturing of the three sets of data.

It normally pays to use the Ha as the 'master' and align the OIII and SII with Ha. Once you have a set of three aligned filter sets, combine them in a graphics program like PhotoShop or The Gimp by pasting the relevant filter data into the R, G and B channels of a freshly made empty RGB file.

There are two main mapping choices here, R(Ha), G(OIII) and B(SII) or the Hubble palette which is R(SII), G(Ha) B(OIII). On an Ha rich nebula, the Hubble palette will give a very green image but the final popular colours can be reproduced using this process.

[jnc71106]

thanks very much it makes a bit more sense now and cheers for the link as well

[martin_h]

Using Nebulosity to register the 3 files is easy, I create a new folder and name it Reg, copy the 3 master files you have into it, then.....goto - Batch - Align & Combine Images, choose Translation & Rotation, and make shure you tick the "Save Each File" button at the top of the box, load the 3 files and pick the first star to align to, and go through the other 2 files, then pick the next star, and do the same, you should then have 3 new files in the folder, all registered to eachother.

The files will be named...."Align_filename"