1. A method for evaluating three dimensional feature on a substrate comprising: illuminating the substrate from a first angle and capturing a first image of the substrate, the first image comprising a plurality of pixels, the pixels having an address, and a value, the address corresponding to a location on the substrate; illuminating the substrate from a second angle and capturing a second image of the substrate, the second image comprising a plurality of pixels, the pixels of the second image being addressed in the same manner as the pixels in the first image, and each pixel having a value; subtracting the pixel values from the first image from the pixel values in the second image on a pixel address by pixel address basis to create a third image, and; processing the third image to determine the quantity of pixels characteristic of three dimensional features therein and rejecting the substrate if the quantity pixels characteristic of three dimensional features exceeds a predetermined value.