Image Processing Tutorial for Starlight Xpress Cameras using AstroArt
	© 2004 John Horsley & Jeff Mammele

Note: This is an ongoing, never ending learning process! There are so many variations between images that no one routine will work for all images. This tutorial presents basic guidelines for image processing and we have found that we get fairly good results. If you find a flaw, or know of an enhancement to these routines, please let us know so we may post it. This way, we can all share in the pleasurable experience of improving our imaging.

Light frames or exposure frames: as a base value (starting point), 600 seconds (10 minutes) will give you a good s/n ratio. Go for 2 hours of total exposure time, for deep sky objects. Take 12 exposures @ 600 seconds.

Take these after exposing the light frames.

• leave the guide window open.
• uncheck X & Y.
• cap the scope.
• take 3-5 exposures @ 600 seconds.

• Change binning to "hi-res interlace mode".
• Uncheck "new window".
• Turn off tracking mode.
• Take 20 exposures. Get a value between 20,000 & 40,000. That number is at the bottom of the image. Look for b =

• cover scope
• take 20 exposures using same time as the flats.

After taking flats & flat darks, be sure to turn tracking back on & change binning back to "hi-res self guide."

• Open preprocessing.
• Put all dark frames into image window.
• Under the Option tab, select "average."
• Uncheck alignment options.
• Click OK.

AstroArt will build an averaged image. Save it as your master dark. Do the same with your flats & flat darks. Now you have your 3 master calibration frames.

Note: dark frames can be reused if temp & exposure time of new light frames are the same. Flats & flat darks must be taken every session.

• Open preprocessing.
• Put your first raw exposure into image window.
• Put your 3 master calibration frames into their perspective windows.
• Click OK and save the image.
• Repeat this process for all remaining raw frames. You will now have 12 calibrated master raws.

• Open your first master raw.
• Open Mike's colour synthesis plug-in.
• Click "white balance" anti-vbe, luminance hpf-off.
• Click batch LRGB.
• Highlight all master raws & open. You will now have 12 each, LRGB's.

• Close mikes & open first lum master
• Select an unsaturated star, then close image.
• AstroArt will save the selected star.
• Open preprocessing.
• Select all blue frames, put them into image box.
• Be sure to close calibration windows.
• Option tab: check average, check auto-align for one star, check confirm each image, click ok. Then you will have your master blue.
• Apply anti-vbe plugin & artificial flat, if any sky glow is present.
• Save the image as your master blue.

Repeat process to get your master green & master red.

Now, the background values of your RGB masters have to be equalized:

• Open your blue master.
• You want a value of 500. To do this: Open arithmetic>add offset function. This number is at bottom of image b = example: if the value is 2500, enter -2000 to get 500. Click on bottom border of image. This will stretch it.
• Then save as your master blue.

Do the same for your green & red.

• Open preprocessing.
• Select all lum frames.
• Place in image window.
• Follow what you did with the RGB frames. You now have your master lum.
• Again, use the anti-VBE and artificial flat plug-in, if skyglow is present.
• Apply the star bloat plugin, DDP and any other filters to build your luminance image.
• Save as your master lum.

• Open your 4 master L,R,G, and B frames.
• Select trichromy (under color) to combine your color frames.
• Adjust color balance if needed.
• Open LRGB synthesis.
• Click your master lum. This will combine all LRGB frames.

At this point, your image should look pretty good. Maybe a little washed out. That's ok. If not, you screwed up!!!

Save the image as JPEG and open it in PhotoShop. If needed, try saturation first, then do whatever final processing is necessary. Crop the image a bit and square the pixels by resizing the image:

• for MX7 & MX9 series cameras, resize to 779 x 580
• for MX5 series cameras, resize to 500 x 373

Crop as required, and finaly save as JPEG, at a file size of around 60-100k (for web use).