Example 5: Full Disc Lunar Imaging

Update 25/04/2013

Please note that this example is using v2.1.4 of PIPP which is a little old now and there have been a few changes to the design since then.  I plan to do an update to this example when I get time and include my processing steps with RegiStax 6 too.

In the meantime I recommend reading this excellent tutorial on full disc lunar imaging which covers the process from capturing the images to getting results out of RegiStax 6.


Right, back to the old example...

This is an example of using PIPP to help with full disc lunar imaging.  This example uses images taken through an 80mm refractor telescope with a Canon DSLR camera and a x2 barlow.

The imaging session resulted in 120 full frame DLSR images like the one shown below.  The individual images are actually 4272 x 2848 pixels, the image below is reduced in size for this web page.

To begin with we start PIPP, add all 120 CR2 files to the source file list and select the 'Optimise Options for Solar/Lunar Full Disc' imaging box.

We continue by working along the tab, so next we look at the 'Input Options' tab.  We note that there are some detailed controls for CR2 files, but as is usual the default values are fine for our processing needs.

So we continue along to the 'Processing Options' tab.  Note that some options have been changed because of the 'Optimise Options For Solar/Lunar Full Disc' imaging control being selected on the first tab, these options have had their colour changed to green.  Basically, object detection has been enabled plus object centring and cropping with a default crop value added.

Also, the 'Convert Colour To Monochrome' control has been enabled which will cause the colour images to be converted to monochrome which will reduce the file size to 1/3rd of the that of a colour image.  If required, this option can be disabled so that colour images can be used which can produce nice results with the moon.  However, we shall leave it enabled and work with monochrome images in this example.

Next we click the 'Test Options' button to bring up the image preview window and check the effect our settings have had so far.  It is immediately obvious that our crop area is too small and needs to be modified.

So we increase 'Crop Width' and 'Crop Height' from 1200 to 2500.

Then we click the 'Test Options' button to check how the modified crop values will work.  We see that although the crop height is correct, the crop width is now too large.

So we reduce the crop width from 2500 to 2000.

Yet again we click the 'Test Options' button to check how the modified crop width value will work.  We see that the crop values look good, but the moon is a little too far to the right in the frame.

We attempt to correct this by adding in an X Offset of 150, guestimated from the image preview window.

Once again we click the 'Test Options' button and check the results on the image preview window.  This time the crop and position looks pretty much ideal.

I personally find that Registax handles the images better if they are all the same brightness, so we shall enable the histogram stretching at 70%.  This will ensure that every frame has its maximum pixels at 70% of maximum value, this gives some headroom to work with once the stacking is complete.

And again we click the 'Test Options' button to see the effect this last change has had.  We see that the image in now brighter, but not too bight.  We do not need to make any more changes to the 'Processing Options' tab.

So we move onto the 'Quality Options' tab.  We see that the quality options have been set to reorder the frame by total pixel value.  This is a great option for detecting frames that have been affected by cloud, but there was no cloud anywhere in the sky during this imaging session so this is unnecessary.  We could simply disable quality estimation, but instead we shall use it to select the best quality (sharpest) frames.  This is the 'Quality Options' tab before we make any changes to it:

To select the best quality frames we change the 'Quality Algorithm Selection' control to select the 'Default PIPP Quality Algorithm'.  As the differences in quality for these type of images is very slight (mainly because the seeing was quite good but also because this type of imaging does not use a long focal length) we change the 'Minimum and Maximum Subsample Values' to both be 2, so that the quality algorithm is applied using the contrast difference between 2 pixel by 2 pixel squares.  Also we are only going to keep the best 100 frames (from the original 120 frames), so 20 frames will be discarded.

This quality selection is not strictly necessary as Registax can also do this, but doing it this was works for me and it reduces the number of frames that Registax has to process.

With the quality options complete we move along to the 'Output Options' tab.  On this tab we see that the 'Output Format' has been set to TIF because of the 'Optimise Options For Solar/Lunar Full Disc' selection on the first tab.  This is ideal for this type of imaging so no changes need to be made to this tab.

So we move onto the 'Do Processing' tab and click the 'Start Processing' button to begin the processing run.

Once the processing run is complete the processing tab looks like this.  Note that from the 120 input frames, 20 frames were discarded by quality and 100 frames were output.  This is what was expected.

A directory of TIFF images has been created, ready to be stacked.

Each image looks something like this, note that the size has been reduced for this web page (click on the image to open a full size version):

These 100 TIFF images were stacked and had wavelets applied using Registax 6 and then some curve tweaks applies using Photoshop.  As usual I will not detail the procedure here as others who I feel are much better at this than me have created good tutorials about this.  However, here is the final image, reduced in size to display on this page (Click on the image to open a full size version):