Streamlined Instructions for Processing Your CCD Camera Images



Here is where you correct your raw image for the thermal noise and the uneven pixel and optical illumination, and then convert to color using one of several possible rendering methods.

* Start up the program CCDOPS by clicking on the desktop icon (do not start things by just finding and clicking on your picture and counting on it to properly open the CCDOPS application - that will cause bad errors very shortly)

* click file -> open and open your first image file (like m27dumbell-1.st2k)

* Note the little information box that pops up first, and note the temperature. That's the chip's temperature. If it's -20C or very close to it, then the dark frame you will want is dk5-20.st2k. That's your first step - subtract the dark frame from the image frame. To do that...

* click utility -> dark subtract and then click on the dark frame appropriate for your photo. It must be the same length of time and the same temperature as the chip or your image will suffer. Now in the little dialog box, find and checkmark the box for auto, and this will automatically scale the photo to best advantage. You should see that your image looks cleaner, much fewer speckled, most of the hot pixels should be fixed. If it doesn't look better, something's wrong and try again.

* click utility -> flat field and then click on the flat field that's appropriate. For any images on the dome 12" scope in or after August 2013, you should use flat16-1.st2k as your flat field. Before you click on it, you should notice that your corners are darker than the center of the images. Now click on the flat frame and OK and you should see your image look a little smoother and mostly, that the corners should now match the rest of the sky brightness. Now you have a fully corrected image!

* click utility -> single shot color and note the color method. It should be sRGB+gamma for most pictures, especially for nebulae and galaxies and comets. Star clusters might benefit from RGB or sRGB or DDP methods. Try 'em and see. BUT - realize that this is NOT the time to try and totally optimize the look of your image. Your goal here is just to make sure the brightest part of your subject isn't overexposed (saturated) and that the faintest parts of your image are not black faded into the sky. The rest of the polishing we do in Photoshop, later.

* Now close out those photos and be sure to not save the black and white frame (since it's the same name as the original raw and if you save it, it'll overwrite the raw image and the raw image will be gone).

* Repeat these steps for each of your 5 minute exposures. Now you'll have .tiff versions of each of your .st2k original images

In Registax

Here is where you stack all your separate 5 minute exposures into one single image. The single image will be smoother, less noisy, essentially an average of all the exposures, and this averages away some of the random pixel-to-pixel shot noise.

* click on the Registax blue icon on the desktop of your Windows computer to start up the program.

* click Select and then highlight all of your exposures for that image subject.

* Now you should see a box with a plus sign in it. Adjust the Alignment box size to 128 is my suggestion, but it might not be critical. Now find a star that is brighter and reasonably isolate, so the box won't get confused about which is your alignment star as it moves through all the images. If you're subject is a comet, use the comet's nucleus. If it's not a comet, do NOT use the center of your subject.

* click Align and you should see the star in each of your photos. If the program can't align on a given image, then click OK and click carefully on the same alignment star for that image.

* In the Limit box, set the number down to 0. This will tell Registax to keep all images with quality above 0, which means it'll keep all your images and not drop any from the final stack. Now click the limit button.

* Now click Optimize and Stack and you should see a graph of quality constructed. It'll take some seconds. You should then see on the left side a set of wavelet processing sliders. Leave them alone, but if you see them, then it stacked successfully. If successful, the stars in the final image will now show any "double vision". If your stack didn't work, it'll be obvious. If it did work, that'll be obvious too.

* Now click Do All and then click Save Image (might be in red) and my convention is to keep the same name but change the numbers to stack. For example, your stacked image of m27dumbell-1.st2k + m27dumbell-2.st2k + m27dumbell-3.st2k should be named m27dumbell-stack.st2k.

* Now your image should look less noisey and smoother. You're ready for Photoshop.

In Photoshop

This stage is a little harder to lay out as a cookbook set of instructions. I tell my students their goal should be to look at your image and try to imagine what it would look like if it were taken with a bigger telescope, under darker skies, with sharper atmospheric conditions. Make it not different, but better, in other words. Here are the kinds of things I usually do...

* click Image -> Adjustments -> hue & saturation and then pump up the color intensity by increasing saturation. Don't change hue, which alters the colors.

* click Filter -> Noise -> Despeckle to get rid of some of the bad pixels

* click the dotted square icon on the left side menu and use it to crop the picture. It's typical that after stacking you'll have some funky borders which are undersampled

* click Filter -> Sharpen -> unsharp mask

* Get Neil Carboni's "Astronomy Tools" Photoshop actions set ($21.95). Note, once you get it, that it is a file type .atn. Place it into the /presets/Photoshop Actions subfolder in your computer's Adobe Photoshop folder. Then "load actions" when you've got Photoshop running. Photoshop actions only need to be loaded once, and forever after when you start up Photoshop they'll be there. Then I'd suggest trying the following actions
-- "make stars smaller" will sharpen your stars
-- "space noise reduction"
-- "enhance DSO" will attempt to bring your faint deep sky object (DSO) up above the level of the sky better.
-- "enhance contrast of edges" will bring out swirly patterns in galaxies and emission nebulae better
-- you can also use some of the actions which make "christmas star" patterns on the stars