The flat image of a diamond in the "fase-up" position. This is the way as a photocamera "sees"	The same diamond observed by the left eye	The same diamond observed by the right eye

Human brain transforms two pictures into stereoscopic one. How does it happen? Is it correct that the brain observes the same picture as the photocamera does? Actually work of the brain on the creating of one stereoscopic image from two initial ones is not a simple averaging of two pictures. The image in the brain can be absolutely different from the average picture seen by the right and left eye correspondingly as well as from the image seen by the "photoreceptor" where the image is the result of observation along one direction.

Considering this phenomenon in application to the leakage of light in diamonds, we face the task how to evaluate areas in diamonds, in which one eye sees the leakage and the other eye does not. In other words what will be in the human brain when one eye observes the white area while the other eye sees the dark one. In this case the human brain will see the white area. When at least one eye sees leakage then the resulting image is also persepted as leakage. For the white background the situation is opposite - the brain feels the black section as the result of superpositioning two pictures.

Another consideration is the case of partial leakage areas in a diamond. On the figures shown below there's a partial leakage under the table seen by the right and by the left eye correspondingly in the "Leakage" model of illumination:

Picture for the left eye in the "Leakage" illumination	Picture for the right eye in the "Leakage" illumination

Literally all the modern conceptions of the diamond cut investigations will bring to the conclusion that the result leakage through the table is negligible for this diamond. It can be shown in the Firescope or in the "Leakage" illumination for the average position of the stone. Taking into account stereovision effect lets us conclude that the result leakage seen by the brain through the table will be more considerable:

The average picture: week partial leakage under the table	The result of stereo effect calculation: moderate leakage under the table

These examples show the work of stereo mode applied in this software. It evaluates the leakage of light from the point of view the real observer - the human head with stereovision.

For correspondence: serg@next.msu.ru