Digital encoding algorithm for pixelated detectors
AssigneeUchicago Argonne, LLC
InventorsMichael P. Hammer, Antonino Miceli, Chris J. Jacobsen
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Abstract
A detector for imaging and efficiently digitizing a spatial distribution of photon flux includes pixel circuits that compressively encode pixel values generated by integrated analog to digital converters (ADCs). On-pixel digital compression circuits (DCCs) implement compression to increase continuous frame rate by reducing the number of bits per pixel while keeping quantization error below Poisson noise. Several mapping algorithms for photon-counting and charge-integrating detectors and compact digital logic implementations are presented.
Claims19
A detector for imaging and efficiently digitizing a spatial distribution of photon flux, the detector comprising:
- a plurality of pixel sensors, wherein each sensor is configured to generate an analog electrical signal indicative of a number of photons detected by the sensor during an integration time interval;
- a plurality of pixel circuits corresponding to the plurality of pixel sensors, wherein each pixel circuit corresponds to a single pixel in the detector and includes:
- an analog-to-digital converter (ADC) configured to generate an M-bit raw digital value based at least in part on the analog electrical signal generated by a corresponding pixel sensor,
- a digital compression circuit (DCC) configured to:
- (i) generate an N-bit compressed digital value, wherein N is smaller than M, based at least in part on the M-bit raw digital value,
- (ii) determine whether the M-bit digital value generated by the ADC indicates the detected number of photons below a threshold value, and
- (iii) set the N-bit digital value to zero in response to detecting that the M-bit raw digital value generated by the ADC indicates the detected number of photons below the threshold value;
- a digital processing unit configured to generate a set of frame data by collecting, from each pixel circuit of the plurality of pixel circuits in the detector, the compressed digital value;
- and
- one or more transmitters, configured to transmit the set of frame data from the detector within a time interval corresponding to a frame rate.
A method for imaging and efficiently digitizing a spatial distribution of photon flux using a plurality of pixels, the method comprising:
- generating, for each of the plurality of pixels, using a corresponding pixel sensor, an analog electrical signal indicative of a number of photons detected by the corresponding pixel sensor during an integration time interval;
- generating, using a different corresponding analog-to digital converter (ADC) for each of the plurality of pixels, an M-bit raw digital value based at least in part on the analog electrical signal,
- generating, using a different corresponding digital compression circuit (DCC) for each of the plurality of pixels, an N-bit compressed digital value, wherein N is smaller than M, based at least in part on the M-bit raw digital value, wherein each DCC is configured to:
- determine whether the M-bit digital value generated by the ADC indicates the detected number of photons below a threshold value, and
- set the N-bit digital value to zero in response to detecting that the M-bit raw digital value generated by the ADC indicates the detected number of photons below the threshold value;
- generating, using a digital processing unit, a set of frame data by collecting, from the each of the plurality of pixels in the detector, the compressed digital value;
- and
- transmitting, using one or more transmitters, the set of frame data from the detector within a time interval corresponding to a frame rate.
Dependencies are inferred from the claim text.