Correction for Harris/Plessey Operator

Bob Fisher

Many publications incorrectly report the matrix M used in the Harris-Stephens or Plessey corner/feature point detector. If $I$ is the image, then the matrix M$(a,b)$ at each point $(x,y) = (a,b)$ is:

$${\bf M}(a,b) = \left[ \begin{array}{cc} \sum_{(u,v)} w_{uv... ...ac{\partial I(a+u,b+v)}{\partial y})^2 \\ \end{array}\right]$$

where $w_{uv} = e^{-(u^2 + v^2)/(2 \sigma^2)}$. The normalizing constant in the Gaussian weighting $w_{uv}$ can be ignored as this is just a constant scaling of M.