PDA

View Full Version here: : Colour processing...what am I doing wrong?


kinetic
28-04-2009, 01:01 AM
Two attempts tonight to get a colour image from my OSC DSI II Colour
camera failed terribly!

I'm not sure what I'm doing wrong.

Firstly I captured M83 with the camera saving RAW FITs
I understand that the capture program Debayers the colour
image (subtracts all the filter factors) and essentially saves
the files as if they were mono.

Then I can process the image as if it was a mono, including subtracting
the Darks (also saved as RAWS)

Then just before stacking, convert them to colour frames again

The frames just before stacking have colour in them...I could see
it if I stretched them just before stacking.
But the stack result turned out Mono...

I'm not sure what I'm doing wrong?...

So then I put the camera in 'save as RGB files' mode.
I then did a capture sequence of the Lagoon.
The lights had colour in them as expected...lots of green naturally
as the green pixels outnumber the R and B.

subtracted darks (RGB darks this time) as normal.
Stacked....again a mono result....!

I'm doing something so obviously stoopid but can't work out what
it is.
The only part that is colour on the 2nd image is the hot pixel artifact showing
as green....if that is any indicator obviously staring me in the face?

Can any owner of a DSI II Colour shed some light on this please?

thanks in advance,

Steve

Alchemy
28-04-2009, 05:58 AM
i know in deep sky stacker you just stack as FITS; just also plug into it your calibration files and lights, , BEFORE doing anything else , you do have to tell the program what camera you are using so it gets the bayer pattern right... cant suggest much else, as i dont use that particular camera.

peter_4059
28-04-2009, 06:37 AM
Steve,

What are you using to stack and what file format is it saving the stack in? If the answer is DSS and TIF I think you'll find a TIF is only monochrome.

You need to create a R stack, G stack and B stack then re-combine them into an RGB image in something like PS.

Peter.

ps the lagoon image looks colour to me.

dannat
28-04-2009, 09:37 AM
Steve, from my limited knowledge programs like DSS do often produce a mono image (i was also stumped) - but as long as you save in a lossless format like fits/tiff/png when you open the stack in a program like PS, you can adjust the color curves & you will see the colour info is there, the stacking has just hidden it - experiment with one of your mono stacks

kinetic
28-04-2009, 11:48 PM
Thanks Clive, Peter, Daniel,

I had another few tries with DSS and Neb.
It definately has colour in it but is so washed out.
Dialing in some saturation brings up the blue but shows up
just how bad the originals were.
The trade off in sensitivity and resolution between the
Mono DSI II and colour version definately shows up here :)

Good thing about the RAWS though is that I got rid of the
dark artifacts while dealing with them in Mono.

Once again...dealt with all dark subtraction in RAW FITS...
then reconstructed before stacking.

Thanks guys for the advice,

Steve