Checkerboard Pattern In Aligned Images

Discussion in 'Image Processing' started by Tom Polakis, Oct 11, 2016.

  1. Tom Polakis

    Tom Polakis Cyanogen Customer

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    I am doing asteroid photometry work in which one step with MaxIm is to align the images. After doing a plate solve, the software does a nice job registering the stars. After alignment, some of the images show the checkerboard pattern, as in the example below. Note that this is a pretty extreme stretch. The graph of the pixel value for the line I drew doesn't show much waviness, so perhaps I shouldn't worry about it. Still, I'm curious if anybody knows what is going on to create the pattern, and if there might be a way to eliminate it. Thanks.

    Tom

    [​IMG]
     
  2. Doug

    Doug Staff Member

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    Is this a color (Bayer pattern) CCD?
     
  3. Tom Polakis

    Tom Polakis Cyanogen Customer

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    No, it's a monochrome STXL-6303 camera. Let me try the same thing using images only east or west of the meridian, and see if the meridian flip has something to do with it.
     
  4. Doug

    Doug Staff Member

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    If you are not at 100% zoom, you may be seeing an aliasing effect between the crude pixel-dropping method that Windows uses, against a very subtle pattern caused by the interpolation algorithm.

    Which interpolation method are you using - bilinear or bicubic? See http://www.cyanogen.com/help/maximdl/Align.htm
     
  5. Tom Polakis

    Tom Polakis Cyanogen Customer

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    I am at 100% zoom, and it still shows up. The "Stack" menus have interpolation method choices, but I see "Bicubic" as the only choice for simply aligning images (not stacking).

    Tom
     
  6. Doug

    Doug Staff Member

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