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Astro Thoughts

Processing Images

Processing deep sky objects

Deep sky objects

Located outside our solar system, often invisible to the naked eye, and require long-exposure photography:

  • Nebulae: Interstellar clouds of dust and gas, such as emission, reflection, or dark nebulae within the Milky Way Galaxy;
  • Galaxies: Vast systems of stars, gas, and dust outside the Milky Way Galaxy;
  • Star Clusters: Dense groupings of stars, including open clusters and globular clusters within the Milky Way Galaxy.  

   

Inspiration

   

 Pixinsight

  • Weighted Batch Pre-processing is done separately for each narrowband image, using appropriate lights, light darks, flats and flat darks, with drizzle applied.
  • Each drizzled master image is deconvoluted, noise reduced and, if needed, gradient corrected.
  • The images are star aligned with Ha image as reference and dynamic crop is applied if needed.
  • Images are corrected with HLP Astro Image Primer and then integrated to form a luminance image, which is then saved starless, having extracted the stars.
  • The monochrome images are combined with pixel maths, either with Hubble palette or the palette of Charles Bracken.
  • Generalized Hyperbolic Stetch and Curves Transformation are then applied. 
  • The starless luminance image, following stretching, is then combined with the stretched colour image.
  • The stars from the luminance image, after stretching, are then put back into the colour image with HLP_starsback.
  • The resulting file is saved as a 16-bit TIFF file.

 

 Topaz Studio

  • The TIFF file is adjusted with denoise, sharpen and enlarged with gigapixel.

 

 Adobe Photoshop

  • The TIFF file is adjusted as required, sometimes expanding with Adobe Firefly, and saved with standard A3+ size, landscape, or, very occasionally, portrait.    

 

Saving files

  • The Pixinsight Master folder (other folders are deleted to save space) is saved on the working computer with the folder name [classification of the image and the date of aquisition] for further work and publishing as needed. Copies are saved to a portable SanDisk extreme drive (to move between locations), G-RAID in one location and internet-accessible NAS storage device in a separate location.

 

 

Objects within the solar system

 

Inspiration

 

For the planets

  • For the planets. I follow the traditional approach of sorting/stacking in AUTOSTAKKERT! (best frames), sharpening in REGISTAX (wavelets), and potential derotation in WinJUPOS to handle rotation. Following this, I adjust the produced file with TOPAZ STUDIO denoise, sharpen and enlarge with gigapixel. I then adjust the image as required with ADOBE PHOTOSHOP, sometimes expanding with firefly, and saving with standard A3+ size, landscape. Rather than using REGISTAX, I have also experimented with PIXINSIGHT.     

 

For the moon

  • For the moon, I sort/stack in AUTOSTAKKERT!, adjust the produced file with TOPAZ STUDIO denoise, sharpen and enlarge with gigapixel. I then adjust the image as required with ADOBE PHOTOSHOP, sometimes expanding with firefly, and saving with standard A3+ size, landscape. I have also experimented with PIXINSIGHT.     

 

For the sun

  • For the sun, I sort/stack in AUTOSTAKKERT!, process the image with PIXINSIGHT, using the Solar Toolbox to colour the monochrome image of the sun, adjust the produced file with TOPAZ STUDIO denoise, sharpen and enlarge with gigapixel. I then adjust the image as required with ADOBE PHOTOSHOP, sometimes expanding with firefly, and saving with standard A3+ size, landscape.

 

Saving files

  • The final TIFF file is saved on the computer with the folder name [object, and date of capture] for further work and publishing as needed, with copies saved to a portable SanDisk extreme drive (to move between locations), G-RAID in one location and internet-accessible NAS storage device in a separate location. 
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