PLANETARY IMAGE PROCESSING

Here is the technique I use for processing images of the planets and the Moon of the solar system. Before starting the treatment, it is necessary to choose the right equipment, to carry out a good preparation, to proceed to the acquisition of the images and lastly, to carry out the processing of the acquired images. At the end of the presentation (see References), I provide my personal detailed processes for each of the software.

Choose the right equipment

  • The fastest possible camera: minimum 30 images / sec.
  • For an estimate of the exposure time, see chapter Suggested exposure times to section The photography of the planets.
  • Have the right sampling. See the chapter Astronomical calculations to section Sampling for imagery of planets.
  • Recommended color video with built-in infrared filter: simpler for the beginner in planetary imaging.
  • Recommended filters: use a polarizing filter for the Moon.
  • Recommended cameras:
    • Choose the mid or high end.
    • For the best value for money, I recommend the cameras ASI of the firm ZWO which are specialized in the imaging of the solar system. For those new to planetary imaging, prefer color camera models.

Preparation

  • Shot near the meridian.
  • Photograph the planets (Mars, Saturn and Jupiter) during the period ofopposition (time when the planet is closest to the earth).
  • Turbulence: minimum 4/5 (good).
  • Wind: less than 15 km / hour.
  • Clean optics.
  • Very good collimation.
  • Heating of the equipment. Set up equipment outdoors at least one hour before shooting.
  • Focusing (MAF): doing the MAF on a Jupiter Moon. For the other planets, perform the MAF directly on the planet. During the MAF, put a high gamma and increase the exposure time which will allow to accentuate the contrast of the image thus facilitating this task. After the MAF, remember to reset the gamma to 50% (recommended standard setting).
  • Keep the image slightly darker to avoid having overexposed sections. I suggest adjusting the exposure time to 75% of the histogram.
  • Number of image pixels for the planets Saturn, Jupiter and Mars: 640 x 480 pixels and less.

Image acquisition

I recommend using the software FireCapture (free software). It is the most complete software for acquiring images of the planetary system.

Image processing

  • Using the software Pipp to decrease the displacement of the planet in the video.
  • Composing in AutoStakkert. The software will rank the best frames in the video at the start of the clip and the worst at the end. We can then easily analyze the images manually from the first to the last. It is recommended that you retain approximately 25% to 50% of the best images in the sequence. For example, if the video contains 1500 images, if 25% of the best are retained, the images retained will be the first 375 images of the sequence. These images can then be viewed individually to ensure their quality. The software will then proceed to compositing the retained images using alignment points on details of the planet's surface.
  • Wavelets with PixInsight (ATrousWaveletTransform) or RegisTax.
  • PixInsight :
    • RangeSelection : Using a mask to process only the details on the edges of the planet (treatment # 16).
    • HDRMultiscaleTransform : To get details on the edges of the planet (treatment # 14).
  • Finishing with Photoshop :
    • Create an image of synthetic luminance.
    • If necessary, use the levels to round the planet.
    • Use of curves to slightly increase the contrasts and nuances of the surface of the planet (treatment # 3). Make a slight S-curve.
    • If needed, Filter | Reinforcement | Emphasis (treatment # 13).
    • Balance colors using curves (click this lien). To adjust the colors of the planet without modifying the colors of the sky background (keep the black tones of the sky background). Most of the time, I slightly adjust the colors of the planet. Also, very useful for removing an unnatural color cast from the planet.
    • Etc…

References :

Here are my personal detailed processes in PDF format for each of the software described above. I use a monochrome camera for photographing the planets. So, for the beginner who uses a color camera, skip the steps regarding the management of the motorized filter wheel:


Richard Beauregard
Sky Astro - CCD

Revised 2021/11/03