Determining light level variation in compressive imaging by injecting calibration patterns into pattern sequence

A method for operating on a stream of light, the method comprising:

• modulating the light stream with a series of spatial patterns in order to produce a modulated light stream, wherein the series of spatial patterns includes first patterns and calibration patterns;
• generating a sequence of samples representing intensity of the modulated light stream as a function of time;
• and
• separating the sequence of samples into a first subsequence of samples that correspond to the first patterns and a second subsequence of samples that correspond to the calibration patterns, wherein the second subsequence of samples represents variation in background light level.

A non-transitory computer-readable memory medium storing program instructions, wherein the program instructions, when executed by a computer system, cause the computer system to:

• supply a series of spatial patterns to a light modulation unit, wherein the light modulation unit is configured to modulate a received light stream with the series of spatial patterns to obtain a modulated light stream, wherein the series of spatial patterns includes first patterns and calibration patterns;
• receive a sequence of samples from a first light sensing device, wherein the sequence of samples represents intensity of the modulated light stream as a function of time;
• and
• separate the sequence of samples into a first subsequence of samples corresponding to the first patterns and a second subsequence of samples corresponding to the calibration patterns, wherein the second subsequence of samples represents variation of background light level.

A system for operating on light from an environment, the system comprising:

• a plurality of mirrors, wherein each of the mirrors is configured to controllably switch between two orientation states, wherein each of the mirrors is configured to (a) reflect a corresponding portion of the light onto a sensing path when the mirror is in a first of the two orientation states and (b) reflect the corresponding portion of the light away from the sensing path when the mirror is in a second of the two orientation states;
• a control unit configured to drive the orientation states of the mirrors through a series of spatial patterns, wherein each of the patterns of the series specifies an orientation state for each of the mirrors, wherein the series of patterns includes first patterns and calibration patterns;
• a light sensing device configured to receive light portions reflected onto the sensing path by mirrors in the first orientation state and to generate a sequence of samples representing a cumulative intensity of the light portions reflected onto the sensing path as a function of time;
• and
• a processing unit configured to separate the sequence of samples into a first subsequence of samples that correspond to the first patterns and a second subsequence of samples that correspond to the calibration patterns, wherein the second subsequence of samples represents variation in background light level.