1. A method of measuring 3D depth of a stereoscopic image, comprising: providing left and right eye input images; applying an edge extraction filter to each of the left and right eye input images; in a processor, determining 3D depth of the stereoscopic image using the edge extracted left and right eye images including: selecting a kernel of pixels for comparison in one of the left or right eye edge extracted images; determining a most similar selection of pixels in another one of the left or right eye edge extracted images; correlating the selected kernel of pixels from one of the left eye edge extracted image or the right eye edge extracted image, with a range of pixels from the other one of the left or right eye edge extracted images, in which the range of pixels from the other one of the left or right eye edge extracted images comprises a search window, said search window: having a height equivalent to the kernel of pixels height, and a user-defined length; or having a user-defined height greater than the kernel of pixels height, and a user-defined length.