Computer Vision – The Integral Image

The Integral Image or Summed Area Table, was first introduced to us in 1984, but wasn’t properly introduced to the world of Computer Vision till 2001 by Viola and Jones with the Viola-Jones Object Detection Framework.

The Integral Image is used as a quick and effective way of calculating the sum of values (pixel values) in a given image – or a rectangular subset of a grid (the given image).

It can also, or is mainly, used for calculating the average intensity within a given image. If one wants to use the Integral Image, it is normally a wise idea to make sure the image is in greyscale first.

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