Correction for pixel-to-pixel signal diffusion

An optical time-of-flight camera, comprising:

• a light emitter;
• a sensor array;
• and
• a computing device configured to correct a digital image acquired by the sensor array to reverse an effect of signal diffusion among pixels of the digital image, the computing device comprising:
• a controller configured to modulate the light emitter and synchronously modulate an electronic shutter of the sensor array, the controller comprising a logic system and a memory system operatively coupled to the logic system, the memory system holding instructions that are executable by the logic system to:
• acquire via the sensor array, for a target pixel j of the digital image, a set of signal values and a set of signal amplitudes each corresponding to a set of kernel pixels i surrounding and including the target pixel j, the set of signal values and the set of signal amplitudes acquired at a plurality of modulation frequencies of light emitted by the light emitter,
• for each kernel pixel i, compute a weighting coefficient based on the signal amplitude of that kernel pixel i and on the signal amplitude of the target pixel);
• compute a first linear combination of signal values corresponding to the set of kernel pixels i, wherein the signal value for each pixel i is weighted by the weighting coefficient corresponding to that pixel i;
• store the first linear combination in memory of the computing device as a corrected signal value for the target pixel j for a first modulation frequency;
• and
• compute and store a second linear combination of signal values for a second modulation frequency, wherein the signal value for each pixel i is weighted by the same weighting coefficient as in the first linear combination.

Enacted in a computing device operatively coupled to an optical time-of-flight camera having an array of optical sensor elements and a light emitter, a method to correct a digital image acquired by the optical sensor elements to reverse an effect of signal diffusion among the optical sensor elements of the array, the method comprising:

• for a target sensor element j of the array of optical sensor elements of the optical time-of-flight camera, receiving a set of signal values and a set of signal amplitudes each corresponding to a set of kernel sensor elements i of the optical sensor elements of the optical time-of-flight camera surrounding and including the target sensor element j;
• for each kernel sensor element i, computing a signed weighting coefficient based on the signal amplitude of that kernel sensor element i and on the signal amplitude of the target sensor element j;
• computing a linear combination of signal values corresponding to the set of kernel sensor elements i, where the signal value for each sensor element i is weighted by the signed weighting coefficient corresponding to that sensor element i;
• storing the linear combination in memory of the computing device as a corrected signal value for the target sensor elements j;
• and
• classifying the target sensor element j into a foreground or background class based on a sign of each signed weighting coefficient.