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Thread: Flat stitching and LCCs

  1. #1
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    Flat stitching and LCCs

    Hi all,

    Maybe a silly question... If I'm flat stitching (for example) panoramic images and applying LCCs for each shot, often I find that correcting for light falloff increases noise and kills detail out at the edges of frame. This was particularly try before I got a centre filter for my RS 55mm.


    Anyway, my question is if I only turn on colour cast correction and turn off light falloff correction, will this introduce strange problems when stitching? I'm assuming that the light falloff is related to basic lens vignetting, but wondered if there might be another kind of falloff / vignetting introduced by the sensor that's related to colour casts?

    Any ideas?

    Thanks,

    TJV

  2. #2
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    Re: Flat stitching and LCCs

    I don't know the answer to your question, but I've seen a similar result: take a panorama of three images, say, and apply LCCs to each one. Then merge them as a pano, and lo-and-behold, they don't match up nicely. The ideal way would be to merge them with a merged (!) LCC - which I don't think is possible.

    So... two ideas:

    1) make sample JPGs for output for quick merging and fiddle with the % of LCC applied (on a layer, or by some way) to get them closer.
    2) make the stitching shots with more overlap so as not to deal with the edges.

    Yes, its not perfect. Not sure what else works.
    Last edited by Geoff; 25th September 2016 at 18:41.

  3. #3
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    Re: Flat stitching and LCCs

    I have found C1 sometimes will "push" on stitches. I assume by flat stitching you are moving the back some degree of side ways movement?

    You can "fade" the light fall setting in C1, I tend to allow it then fade it back. You can also apply a gradient filer towards the edge to also help.

    The Cf makes a huge difference, as the amount of light fall off at time of capture can be greatly reduced thus much less noise.

    Paul C

  4. #4
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    Re: Flat stitching and LCCs

    There are two ways to counter the corner noise after applying LCC:

    a) Use a center filter;

    b) Upgrade to CMOS to get more dynamic range.

    For seamless stitching I find it helpful to use PTGui when exposures among frames do not match perfectly.

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