Steve on Image Processing

March 7th, 2006

Spatial transformations: Useful toolbox documentation links

I've received some comments and e-mail asking how to apply the spatial transformation ideas I've been writing about to images. When I started this series, I naively assumed that Image Processing Toolbox users who were interested in spatial transformations would already know about the function imtransform. I was wrong about that, as I've already written.

You can use imtransform and maketform to apply several types of transformations to images, including affine, projective, and custom. In addition, the image registration function cp2tform can make more types of transforms, including linear conformal, polynomial, piecewise linear, and local weighted mean. Since it's going to be a few more weeks before I get into the specific details of imtransform and friends in this blog, I thought I'd provide some pointers to help readers who need the information now. Here are some links:

By Steve Eddins

09:29 UTC | Posted in Spatial transforms | Permalink |

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3 Responses to “Spatial transformations: Useful toolbox documentation links”

  1. Hulya Yalcin replied on March 8th, 2006 at 04:20 UTC :

    Hi Steve,

    Are you aware of Peter Kovesi’s web site?
    He has developed some Matlab code to compute
    the dominant motion transformation between
    two successive frames. His code is publicly available
    in his web page.

    It would be nice if you guys integrated those
    matlab routines into matlab as part of the demo
    for spatial transformation.

    To use matlab spatial transformation routines, one
    has to select the control points. But computer vision
    researchers have long been developing algorithms to
    automate this. They first find features on the two
    frames and then they match them. Once they are
    matched, a dominant spatial transformation is
    computed from matched features using RANSAC.

    Hulya

  2. Steve replied on March 8th, 2006 at 09:23 UTC :

    Hulya - thanks for the tip. We’ll take a look. We wouldn’t use someone else’s code directly, of course - that wouldn’t be ethical or legal.

  3. Steve replied on March 31st, 2006 at 08:20 UTC :

    Arunkumar - See this post.

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Steve Eddins manages the Image & Geospatial development team at The MathWorks and coauthored Digital Image Processing Using MATLAB. He writes here about image processing concepts, algorithm implementations, and MATLAB.

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