defocus

verb

1. (transitive)To cause (a lens, or a beam of light or particles, etc.) to be out of focus.

noun

1. (uncountable)The process of going out of focus.
2. (uncountable)The distance by which the focal point is in front of (positive defocus) or beyond (negative defocus) the image or target surface.

   “Fundamental to the concept of recovering the depth by measuring defocus is the relationship between the focused and the defocused images of a scene.”