Processing with Photoshop CS2 - Adjusting Levels, Curves & Colours
Different people have different method of processing. I'm simply showing some ways which I go abouts on processing my images. Open Photoshop CS2 and load your saved stacked file.
The first step I do is lower the level bar graph to roughly as seen in the image below. The stacked image should be more brighter than an actual light frame.
Next step I adjust the Curves to roughly around the point as seen below. At the sametime, watch your image as you don't want to overexpose it.
I now go back to Levels and lower the black points. You want to increase the right hand side (White Point) but also lower the left hand side (Black Point).
Repeat these steps about 3 - 5 times (Raising Curve and Levels) depending on the magnitude of your object. Since ETA Carina is a bright Nebula, i normally do only twice. Always observe the histogram when you do this. Once i am satisfied, open up the level box again, on the bottom right hand side, you'll see 3 small button boxes. Select the grey point button box and click the background of the nebula. This will balance the background colour.
Next step, open up Channel Mixer. I slowly go through each channel to adjust the colours which I am happy with.
Once this is done, go back into Levels and lower the black triangle point. Ensure that you don't clip the black point. An example of clipping can be seen below. I noticed alot of people tends to do this so they can get a more black background. You are just cutting out the details. A big no no to clipping unless you really have to.
Another note to watch out on when adjusting Levels. If you raise the white triangle (White Point) too much, you'll overexpose the image loosing alot of important data. This is another big no no. Example can be seen below.
Once i am happy with it, I norally zoom right in and use Unsharp Mask. Don't set the amount of Unsharp Mask too much as this will also remove details.
Thats it for now.