Sub-Pixel Maximum

Ever needed to find the position of the maximum of a peak in an image to sub-pixel precision? Examples are finding the peak energy in Fourier space, or the location of a peak in Hough space. One simple method that I have used with some success is a simple quadratic interpolation, which is performed once for each axis.

Sub-Pixel Peak finding recipe...
Firstly, you take the value of your highest point and its neighbours (Pa, Pb and Pc). Assuming the three points are equally spaced and bracket the top of the peak, you can solve for the position of the 'true' maximum using:

x = 0.5*(Pa - Pc) / (Pa-2Pb+Pc)

The value of x will range between -0.5 and +0.5, which is relative to your maximum pixel.
Jason Dale. www.visionexperts.co.uk

New Year. New Blog

In an effort to pay back some of my huge debt to the internet, I've decided to put a little something back into the web-o-sphere. And seeing as I'd like it to be something useful, I'm going to share the stuff that I find useful, for the benefit of image processing people everywhere.