XI. Post Processing

This is the final step, and arguably almost as hard as planning. After
taking down the telescope and mount, putting everything away, and going
to work tired the next day, the images might become forgotten and stay
in their raw form on the camera or on the computer. It takes dicipline
to find the time for processing, but this is where the real pay-off is.

  1. Calibration (ImagesPlus, RegiStax, or DSS)
    1. Convert to *.tiff
    2. Subtract Darks from Lights
    3. Divide Lights by Flats
    4. Bayer Interpolate
    5. Convert to Linear Color
  2. Evaluation
    1. Review each frame
    2. Check for flaws
    3. Eliminate substandard frames
  3. Align and Stack
    1. RegiStax: (Planetary)
      1. Select the .avi file
      2. Set Alignpoints
        • Find a clear/sharp frame
        • Manually set align points
      3. Align
      4. Limit: Best Frames Use judgement, about 50%
      5. Stack: Complete in Registax or proceed to PhotoShop
      6. Wavelet
        • Sliders
          • All off except #1
          • Denoise: 0.25
          • Sharpen: 0.15
        • RGB Align: Click Estimate
        • Brightness/Contrast: Experiment
        • Historgram:
          • Move red slider to right of peaks
          • Click Stretch
        • Gamma: Bend the curve upward
        • RGB Balance: Autobalance
        • Click Do All
      7. Save (16 bit TIFF)
    2. DeepSkyStacker: (DSOs)
    3. ImagesPlus
  4. Normalized (Multiple ISOs only)
  5. Adjust (PhotoShop)
    1. White Balance
    2. Non-linear Stretch
      • Image > Adjustments > Curves
      • Click the settings gear
      • Load the preset curve (STRETCH.ACV)
    3. Neutralize Background
      • Image > Adjustments > Levels
      • Select the graypoint eyedropper
      • Click in the sky background
      • The RGB levels should be approximately equal
    4. Flatten the Field (if needed)
      • Duplicate the image
      • Filter > Noise > Dust & Scratches
      • Radius = 30 pixels
      • Healing Brush Tool > Healing Brush Tool
      • Diameter = 100 pixels
      • Alt - Click near stars that remain visible
      • Paint over
      • Click
      • Back to original image
      • Image > Apply Image
      • Blending Mode = Subtract
      • Set target as original image
      • Set source as the blurred copy
      • Opacity = 100%
      • Scale = 1
      • Offset=50
    5. Set Black Point
      • Select the Color Sampler Tool from the eyedropper tool
        on the toolbar Brings up the Info window)
      • mage > Adjustments > Levels
      • Slide the black point toward the right until RGB levels are 30 - 40
    6. Fix Imperfections
  6. Enhance
    1. Mask Highlights and Enhance Shadows
    2. Enhance Color
    3. Reduce Noise
  7. Sharpen
  8. Archive