[Insight-users] Applying ImageToHistogramFilter to a specified region

[Richard Beare]

Your best hope is if your application allows you to use a sliding
window approach - i.e you want to make use of histograms for regions
centred at every (or almost every) voxel. These work by updating a
histogram, rather than creating it from scratch every time. Some of
the review code uses this for various types of filtering, although it
doesn't use the histogram infrastructure. Check the
*MovingHistogramImage* filters. I guess you could look at adapting the
same approach to the ITK histogram. Of course, if you only want to use
8 bit images then you're best off with simple 256 entry tables because
everything will be much faster.

On Fri, Sep 16, 2011 at 11:26 PM, David Doria <daviddoria at gmail.com> wrote:
> I just learned how to use SetRequestedRegion, but this concept only works
> for filters that output an image. What is the best way to compute the
> histogram of pixels in a certain region of an image? Of course using
> a RegionOfInterestImageFilter before the ImageToHistogramFilter works fine,
> but if I have to do this on millions of image patches it is quite slow.
> Thanks,
>
> David
>
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