This is where the magic happens.  This tutorial will describe all the steps used to turn a raw video clip into this final image of Mars.

Above:  On the left is a single frame from the video clip of Mars.  On the right is the final processed image.  Image by Rick Auerbach and Scott Tucker.

Outline of Procedure

Registax

• Select reference frame

• Align frames

• Limit processing to best frames

• Optimize alignment

• Stack frames

• Apply wavelet filter

• Color balance, etc.

• Save

Adobe Photoshop

• Levels

• Color Balance

• Crop

• Save

Selecting Initial Frame

Begin by opening the video clip in Registax.  Select the LRGB checkbox, which will allow some fine tuning of the image at a later step.  Click on the slider at the bottom of the window and use the arrow keys on the keyboard to step through the frames one at a time.  Select the best looking frame for your reference frame.  There won't be that many different-looking frames, so something in the first 50 is normally sufficient unless the seeing changed dramatically during the video.

Choose an Alignment Box Size from the top menu that allows you to select the entire planet.  Move the box over the planet and click.  This will bring up the FFT Spectrum window.  Increase the FFT Filter value until there is only a single colored dot in the middle of the window, with no colored edges or corners around it.  This makes the alignment more precise.

Click the Align button at the upper left and Registax will begin aligning and sorting the frames.  A 2000-frame video will take several minutes to fully process.

Limit Frames

Once the images are aligned, a window appears showing a graph of the quality of the images and their alignment differences.  The best images are on the left, the worst frames on the right.  A vertical green bar indicates the cutoff point for limiting which frames to use.  Use the slider bar at the bottom of the window to move the green bar to the desired position.  For this example, it was moved until just over 40% of the total frames were selected.  A few more frames will be cut out in a later step, so if I want 800 frames in the end, I select a few more at this point.

In this case, the best 850 frames were selected, as shown in the stacksize display at the bottom of the main Registax screen.

Optimize

After limiting the frames, Registax will optimize the alignment based on only the selected frames.  The default settings were used for this step.  The Optimize command was used rather than Optimize & Stack.  This allows stacking to me done in a separate step, giving you more control over the result.

Stacking

Select the Show Stackgraph checkbox.  In this window you can limit the frames again, this time based on their alignment differences.  If the difference is too great, you can reject the frames and the result will be a better stacked image.  Use the left slider to move the horizontal line down, cutting off some of the peaks in the Difference graph.  This rejects the frames with the worst alignment.  In this case the Difference Cutoff was set to leave 800 total images.  In other words, the 50 worst-aligned images were rejected.

Press the Stack button and the software will combine the selected frames.  The result is an image which is blurry but has far less noise than the original single frame.
 

Above:  800 frames stacked

Wavelet Filter

Now the magic of Registax.  The Wavelet Filter enhances the image to bring out incredible detail.  Each layer in the filter operates on a different level of detail in the image.  This step if more art than science, but in general the layer sliders will have the pattern shown below, with each slider moved slightly farther than the one above.  Play around to see what you like.  If you find a good setting, you can save a wavelet scheme.  The slider settings tend to be the same for a given planet, so I have schemes saved as "Mars," "Jupiter," etc.

After setting the sliders you will see an incredible amount of detail appear in the image.

Above:  The stacked image after wavelet filter processing.  Note the incredible difference between this image and the stacked image.

Other Adjustments

By choosing the LRGB setting in the initial Registax window, you can now change how much each channel, red, green, and blue, contribute to the final luminance layer in the image.  Note that this adjustment does not affect the actual color of the image (this is done later).  What the LRGB Mixer does is to blend the amount of each color channel to create a luminance image.  Changing the settings will change what details in the image are enhanced.  Play around to see what looks best.  For Mars and Jupiter, bringing up the red slider usually brings out more detail.

To change the actual color of the image, use the RGB Balance control.  For this image, the amount of red was bumped up, while the amounts of green and blue were decreased slightly.  Usually only a slight adjustment is necessary.

Sometimes adjusting Contrast and Brightness can help and image, although in some cases it will not.  This is also something you can do with more control in Photoshop.  For this image, increasing the contrast from 100 to 110 helped a bit.  Be sure not to overdo things with this command as it can easily result in the image being overexposed and washed out.

Once these settings are done, go to the Final tab.  In this window you can fine tune the image.  In this case, Flip Y was selected to put the north pole on top.  If you like, you can rotate the image, which is ideal for a subject like Saturn when you might want the rings at a certain orientation.  Saturation can be adjusted here, but this is something that can be done in Photoshop as well.

Saving Files

If you plan on opening a file to process it further in Photoshop, save it as a 16-bit TIFF file in Registax.  This avoids any loss in quality.  You can then save the file in Photoshop as a JPEG for emailing or posting on a website.  Photoshop gives you more control over this than Registax.

Processing in Photoshop

Adjustments in Photoshop were minor for this image.  For details on aesthetic image adjustment in Photoshop, see the tutorials in this section.  For this image only Levels and Saturation were adjusted.

I always save the final processed image as a TIFF file in Photoshop, just in case I need to go back and play around with it some more later.  Then I resave it as a JPEG for display purposes.  If I change my mind about something later, I can always go back to the TIFF image.  Adjusting a JPEG after the fact is not recommended because you will lose image quality each time you resave a JPEG file.

Above:  The final Mars image.  Mars was over 40 million miles away when this image was taken.  Newton crater is about 300 km wide, or about 0.9 arcseconds at this distance.

Mars Processing Example