The brain uses this information to accomplish stereopis - the perception of depth in a static scene.  This is a topic that a some stereo photographers may want to consider............
 

This crosseye stereo pair is only a fair intensity match with disparity mostly due to depth:
 

We now subtract the left image from the right and show the resultant "disparity" image.
The left image is inverted, turned 50% transparent, and registered with the right image.  Objects in far field of the image goe nearly gray.  Near objects are not in registration and show significant differences.  Overall, the image is B&W since the colors have been "nulled" by subtraction.  The separation between the bright and dark images is related to their distance.

Apparently, images from the eye are sorted and routed to dedicated processors.  Stereoscopic perception compares the left and right channels to show the difference.   The image below is a simple subtraction of right from left  and is like what a disparity channel would see.  Brain functions use dedicated processors to handle "sparse" or compressed data for hand-off to the next level up.  The inputs from many separate processing channels like color(s), motion, and detail, ultimately feed the mind's eye.

More examples:
Color pair disparity comparison matrix images

Complimentary contrasting colors disparity image
Photogrammetry

A model for intradendritic computation of binocular disparity  is a PDF for download.   Figure 5 shows the role of contrast in disparity function.