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Not all contrast illusions can be so easily explained. This image, called White's Illusion appears to defy lateral inhibition.
Which rectangle is lighter, A or B?
Almost everyone who looks at this illusion asserts that B is lighter than A. But as you may have guessed, they are in fact exactly the same shade of grey.
Lateral inhibition fails to explain this phenomenon. Rectangle A is surrounded by more black than white. Rectangle B is surrounded by more white than black. Lateral inhibition would tend to make rectangle A appear lighter, and B darker, but White's Illusion has the opposite effect. The illusion cannot be explained at the level of the retinal ganglion.