Steve on Image Processing

Results for: Spatial transforms

Spatial transformations chapter in new edition of Digital Image Processing Using MATLAB 16

Posted by Steve Eddins,

Spatial transformations chapter in new edition of Digital Image Processing Using MATLAB  In January 2006, the first month of this blog, I wrote the following: "Section 5.11 of Digital Image Processing Using MATLAB covers spatial transformations. I'm interested in expanding this material to a full chapter. I'd like to use this blog to explore these topics and get your feedback about them." Well... read more >>

Viewing output-space coordinates for a transformed image 14

Posted by Steve Eddins,

Viewing output-space coordinates for a transformed image  Blog reader Ram asked a question last week that I hear fairly often: When you apply a spatial transformation to an image, how can you see the x-y coordinates when you display the image? The answer has three steps: 1.... read more >>

Use makehgtform for 3-D rotation 8

Posted by Steve Eddins,

Use makehgtform for 3-D rotation  Developer Mike G. read my recent post about three-dimensional image rotation and suggested that users might want to use the MATLAB function makehgtform to construct the affine transform matrix. It has some convenient syntaxes. As an alternative to the code I posted, Mike says you could do something like this: ... read more >>

Responses to reader challenge 3

Posted by Steve Eddins,

Responses to reader challenge  Thanks to Kimo Johnson and Perttu Ranta-aho for responding to my custom spatial transformation challenge. Contents Kimo's submission ... read more >>

Spatial transformations: Three-dimensional rotation 72

Posted by Steve Eddins,

Spatial transformations: Three-dimensional rotation  Blog reader Stephen N., who's been following my posts about spatial transformations, asked me last week how to rotate a three-dimensional image. ... read more >>

Reader challenge: Custom spatial transformations 10

Posted by Steve Eddins,

Reader challenge: Custom spatial transformations  Were you intrigued by the custom spatial transformations I showed last week? Here's a challenge for you: Create a sample image transformation that is in some way creative, interesting, or just plain fun to look at. Use maketform('custom',...) and imtransform. Send an M-file script that demonstrates the idea to Steve.Eddins@mathworks.com.... read more >>

Spatial transformations: Defining and applying custom transforms 20

Posted by Steve Eddins,

Spatial transformations: Defining and applying custom transforms  Blog reader David A. asked me a while back about how to transform an image based on some mathematical function. For example, the online paper "Visualizing complex analytic functions using domain coloring," by Hans Lundmark, has an example of defining a... read more >>

Spatial transformations: Handling noninvertible cases 6

Posted by Steve Eddins,

Spatial transformations: Handling noninvertible cases  I've written previously about how imtransform uses inverse mapping to compute the input-space location corresponding to each output pixel. I've also written about how imtransform uses the forward mapping to determine the location of the output image in output space. But what... read more >>

Spatial transformations: Translation confusion 45

Posted by Steve Eddins,

Spatial transformations: Translation confusion  The last time I wrote about spatial transformations, I explained that imtransform uses the function findbounds to locate the transformed image in output space. By default, imtransform computes an output image grid that is just big enough to capture the output image, wherever it is located. ... read more >>

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