Patent ID: 8760542

Claim:
A system comprising: a light modulation unit configured to receive a first stream of light from an environment through a first optical input path and to modulate the first light stream with a series of spatial patterns in order to produce a modulated light stream, wherein the light modulation unit includes a plurality of light modulating elements configured to modulate corresponding portions of the first light stream, wherein each of the spatial patterns specifies an amount of modulation for each of the light modulating elements; a light sensing device configured to receive the modulated light stream and to generate a first sequence of samples representing intensity of the modulated light stream as a function of time; and a light power meter configured to receive a second stream of light from the environment via a second optical input path that is separate from the first optical input path, and to capture a sequence of measurements of power of the second light stream over time; a processing unit configured to compensate the first sequence of samples for variation in ambient light level using the sequence of power measurements in order to obtain a compensated sequence of samples, wherein said compensating is performed according to the expression I CMPN ( k )=( I MLS ( k )− I A ( k ))/ I B ( k ), wherein I CMPN (k) represents a current sample of the compensated sequence, wherein I MLS (k) represents a current sample of the first sequence of samples, wherein I A (k) is based on one or more power measurements of the sequence of power measurements, wherein I B (k) is also based on one or more power measurements of the sequence of power measurements.