1. A method comprising: determining a first intermediate computation based on even pixels of an image vector associated with a first image, wherein the first intermediate computation includes calculating a box filter value for an even pixel of a plurality of even pixels aggregated to exclude odd pixels; determining a second intermediate computation independent from determination of the first intermediate computation and based on odd pixels of the image vector, wherein the second intermediate computation includes calculating a box filter value for an odd pixel of a plurality of odd pixels aggregated to exclude even pixels; combining the first intermediate computation and the second intermediate computation into a Hessian matrix computation; and matching the first image to a second image based at least in part on the Hessian matrix computation.