Binocular Disparity - Computing Disparity Using Digital Stereo Images

Computing Disparity Using Digital Stereo Images

The disparity of features between two stereo images are usually computed as a shift to the left of an image feature when viewed in the right image. For example, a single point that appears at the x coordinate t (measured in pixels) in the left image may be present at the x coordinate t - 3 in the right image. In this case, the disparity at that location in the right image would be 3 pixels.

Stereo images may not always be correctly aligned to allow for quick disparity calculation. For example, the set of cameras may be slightly rotated off level. Through a process known as image rectification, both images are rotated to allow for disparities in only the horizontal direction (i.e. there is no disparity in the y image coordinates). This is a property that can also be achieved by precise alignment of the stereo cameras before image capture.