Processing solar images

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This section is mainly to add notes and information that is useful during planning an observing session and then working on it.

  1. Processing Stage 1. AutoStakkert 3
  2. Processing Stage 2. Registax  6 or imPPG
  3. Processing Stage 3. Photoshop

       
Processing Stage 1. AutoStakkert 3

a) Start by loading the flat frame video. Go to Image Calibration-> Create master frame Save the master flat with an indicative name.

(b) Load the surface video. Use Surface and Improved Tracking.

From Image Calibration load the master flat just created. Click Analyse. When done create alignment points. Set the AP size to 32 and select Place AP grid. Use the best 10% of the frames (or more if the analysis graph stays well above the 50% line for further), deselect Sharpened. Click Stack.

(c) Load the prominence video. Clear the load flat. Move the anchor to the large prominence and select Analyse.

Use the same alignment size and by hand set alignment points over the areas of interest – the prominences, but avoid the main disc. Do this by rapidly clicking as the mouse is moved to create the points. Stack as before.

There are now three images, the flat, the surface and the prominences. The flat will not be used again. (or more if the analysis graph 

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Processing Stage 2. Registax 6

The purpose is simply to do an initial sharpening. After some trial I found that imPPG was better for sharpening the surface, although Registax seems better – at least for me – for prominences

If using Registax for the surface image try the following settings for the wavelets. Leave the de-noise and sharpen as they are.

  1. 7.3
  2. 16.5
  3. 60.7
  4. 14.6
  5. 18
  6. 23

Adjust these to give the best sharpening – but not over sharpened. Select Do all and then Save.

For the prominence try as a start:

  1. 1.0
  2. 6.1
  3. 46
  4. 10.4
  5. 15.3
  6. 17.7

Adjust these to give the best sharpening – but not over sharpened. Select Do all and then Save.

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Processing Stage 3. Photoshop

For the prominence it is worth a try to get the area around the prominences as dark as possible without losing their detail. Levels helps by moving the black point to the right to remove low intensity pixels, but not to the levels of the prominences. Also try contrast. On occasions I have used curves lifting the area of intensity occupied by the prominences. I am sure that this needs more practice and other more experienced will have better advice. To further sharpen I find the unsharp mask the best tool to use generally.

Then load the surface. Again, it can be further sharpened – and again I prefer unsharp mask but a variety of tools are available.  Unlock the level. Copy and paste the prominence, and then move the surface layer to the top.

Use the magic wand tool and click in the black area. Make sure contiguous is set and the tolerance is increased upwards till the wand selects right to the edge of the disc. Right button click and set a small feather – just a few pixels – experiment with what suits. Then hit delete and OK to remove the black area and let the prominence show through. (Some suggestions invert the image or use difference levels – but in the area of a sunspot, where the image area is dark even in h-alpha, that looks wrong turning the area light.)

The images can now be aligned. Make any further adjustments while the layers are separate. For example, the centre slider in levels can give more of a sphere effect. Finally flatten the image and crop anything not wanted.

To colour the image set the mode to RGB. Use levels and from the rgb drop down select red. Move the centre slider to the left to about 1.6. Then set the green to 0.8 and the blue to 0.4 to 0.2. The blue at the end gives the greatest control of the final colour. Save the final image.

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