Processing Lunar AVI's Using RegiStax 5 

 (by Bob Pilz)

Stack Tab (figure 8)

General Settings

 Under Multi-point stacking options:

·        Check Fast method. I’ve never found any difference leaving this unchecked, and, as its name indicates, it is a lot faster.

·        For Use feather of I find a value of 3 works well. This specifies the amount of blending that occurs between adjacent APs so that no visible seam will exist.

Check Show Stackgraph under Stacking Options. In the Stackgraphs­ Panel I do the following:

·        In the lower graph I use the up/down arrow box under Alignpoint to go through and examine the difference graph for each AP. I look for two things:

1.     Does the difference graph look “strange”? Is it abnormally spiky or have a large “step” somewhere in it? These indicate APs that didn’t align or optimize correctly probably due to an ill-defined feature and/or low contrast. I disable these APs by checking Show alignment sections under Multi-point stacking options and un-checking that AP number in the Alignmentpoints dialog box that pops up. I don’t typically see problems here, but it needs to be checked.

2.     If the difference graph for an AP shows a few larger vertical spikes, the frames causing them can be removed from that AP’s stack. Use the vertical slider to the left of the graph until the horizontal green line covers the spikes. Using the slider to eliminate many/most spikes seems like it should be a good thing, but I have not found it to be useful, so I just eliminate the very worst ones.

·        Factors such as the specific camera used, gain setting, sharpening workflow, etc. determine how many frames for a given AVI need to be stacked together to sufficiently reduce noise in the final image. Based on experience, I generally have a rough idea of how many frames I will need, but I find it best to stack different numbers and then later after further post-processing determine which gives the best final image.

So at this point, I use the slider at the bottom of the top graph to globally set the number of frames to be stacked at each AP. In this example I’ve set the number to be 150 which then gets reflected in the number shown for each AP. Then click on Stack. After stacking completes, click on Save Image. I save the image as a PNG file. It doesn’t matter as long it is saved in a format that supports 16-bit images.

·        I repeat the above step by changing the upper slider to smaller and smaller stack sizes and saving each result for later use.

As an aside, a realistic example would be limiting the number of frames after align to 450. Then in stacking, I would stack 400, 300 and 200 frames and save the results for each. The difference between 450 and 400 is a cushion to allow using the difference slider for an AP to reduce “spikiness” and still end up with at least 400 frames available.


    Figure 8.