Error detecting and correcting structured light patterns

Abstract

Techniques are disclosed for detecting image depth in three-dimensional (3-D) surface imaging. The disclosed techniques can be used, for example, to provide structured light encoded with a coded word that includes error-correcting code (ECC). The ECC is effectively configured to detect and correct data errors as may result, for example, from the presence of ambient light and/or camera-noise-causing errors during imaging. In an example case, the coded word is a 15-bit pattern provided in a 3×5 matrix and including: (1) nine data bits of disparity code; (2) five ECC bits for correcting an error and detecting two errors; and (3) one 8-bit/10-bit encoding bit to ensure the presence of a transient pixel in the data for white threshold level detection. Greater or lesser bit quantities and varied bit partitioning matrices can be provided, as desired. In some cases, imaging robustness and/or power usage can be improved using the disclosed techniques.

What is claimed is:   
     
       1. An imaging system comprising:
 a light source; 
 a patterned mask that is patterned with a coded word which includes an error-correcting code (ECC), wherein the patterned mask is configured to transmit light emitted by the light source, wherein the transmitted light is structured light that is encoded with the coded word; and 
 an imaging input device which is configured to receive the structured light. 
 
     
     
       2. The system of  claim 1 , wherein the coded word is configured to correct one data error and to detect two data errors. 
     
     
       3. The system of  claim 1 , wherein the coded word is configured to detect a quantity of data errors, and wherein an output power of the light source is at least one of increased and decreased based on that quantity of detected data errors. 
     
     
       4. The system of  claim 1 , wherein the coded word comprises a plurality of data bits and ECC bits. 
     
     
       5. The system of  claim 4 , wherein the plurality of data bits comprises a disparity code. 
     
     
       6. The system of  claim 5  further comprising one 8-bit/10-bit encoding bit to provide at least one transient pixel for black and white intensity level detection. 
     
     
       7. The system of  claim 1 , wherein the coded word comprises a 10-bit representation of 8-bit disparity and five ECC bits. 
     
     
       8. The system of  claim 1 , wherein the coded word is provided in at least one of a 3×5 matrix, a 4×4 matrix, a 4×5 matrix, and a 5×5 matrix. 
     
     
       9. The system of  claim 1 , wherein the coded word includes nine data bits comprising a disparity code, five ECC bits comprising a Hamming code, and one 8-bit/10-bit encoding bit. 
     
     
       10. The system of  claim 1 , wherein the patterned mask comprises a plurality of masks, each mask pixel patterned with a single bit of the coded word, one sub-set of the plurality of masks being configured to transmit temporal coded light and another sub-set of the plurality of masks being patterned with ECC bits. 
     
     
       11. A computing device comprising the imaging system of  claim 1 , the computing device comprising at least one of a laptop/notebook computer, a tablet computer, a mobile phone, a smartphone, a personal digital assistant (PDA), a cellular handset, a handheld gaming device, a gaming platform, a desktop computer, a smart television, and a videoconferencing system. 
     
     
       12. A non-transitory computer-readable medium encoded with instructions that, when executed by one or more processors, causes a process for three-dimensional (3-D) imaging to be carried out, the process comprising:
 illuminating an object with structured light encoded with a coded word including an error-correcting code (ECC); 
 capturing structured light which is reflected from the object; and 
 comparing the reflected structured light with the original structured light to extract a 3-D surface shape of the object illuminated by the structured light. 
 
     
     
       13. The non-transitory computer-readable medium of  claim 12 , wherein the coded word is configured to correct one data error and to detect two data errors. 
     
     
       14. The non-transitory computer-readable medium of  claim 12 , wherein the coded word comprises a plurality of data bits and ECC bits. 
     
     
       15. The non-transitory computer-readable medium of  claim 14 , wherein the plurality of data bits comprises a disparity code. 
     
     
       16. The non-transitory computer-readable medium of  claim 15  further comprising one 8-bit/10-bit encoding bit to provide at least one transient pixel for black and white intensity level detection. 
     
     
       17. The non-transitory computer-readable medium of  claim 12 , wherein the coded word comprises a 10-bit representation of 8-bit disparity and five ECC bits, and wherein the coded word is provided in at least one of a 3×5 matrix, a 4×4 matrix, a 4×5 matrix, and a 5×5 matrix. 
     
     
       18. The non-transitory computer-readable medium of  claim 12 , wherein illuminating the object with structured light is performed using a light source and a patterned mask that is patterned with the coded word, wherein the patterned mask is configured to transmit light emitted by the light source, wherein the transmitted light is structured light that is encoded with the coded word. 
     
     
       19. The non-transitory computer-readable medium of  claim 18 , wherein the coded word is configured to detect a quantity of data errors, and wherein an output power of the light source is at least one of increased and decreased based on that quantity of detected data errors. 
     
     
       20. The non-transitory computer-readable medium of  claim 12 , wherein illuminating the object with structured light is performed using a light source and a plurality of masks, each mask pixel patterned with a single bit of the coded word, one sub-set of the plurality of masks being configured to transmit temporal coded light and another sub-set of the plurality of masks being patterned with ECC bits, wherein the coded word is configured to detect a quantity of data errors, and wherein an output power of the light source is at least one of increased and decreased based on that quantity of detected data errors. 
     
     
       21. A structured-light system comprising:
 a transmitter comprising:
 a light source; and 
 a patterned mask that is patterned with a coded word which includes an error-correcting code (ECC), wherein the patterned mask is configured to transmit light emitted by the light source, wherein the transmitted light is structured light that is encoded with the coded word; and 
 
 a receiver comprising:
 a first-in/first-out (FIFO) module configured to contain imaging data; 
 a level detection module communicatively coupled with the FIFO module; 
 an ECC module communicatively coupled with the level detection module; and 
 a 10-bit/8-bit encoder module communicatively coupled with the ECC module; 
 
 wherein the receiver is configured to output a disparity code that is used in generating the coded word. 
 
     
     
       22. The system of  claim 21 , wherein the coded word is configured to detect a quantity of data errors, and wherein an output power of the light source is at least one of increased and decreased based on that quantity of detected data errors. 
     
     
       23. The system of  claim 21 , wherein the level detection module is configured to:
 calculate a first average threshold based on pixels acquired from the imaging data of the FIFO module; 
 calculate a first mean value of pixels above the first average threshold; 
 calculate a second mean value of pixels below the first average threshold; and 
 calculate a second average threshold based on the first and second mean values, wherein the second average threshold is used as a brightness threshold for pixel detection, and wherein a standard deviation of pixels above and pixels below the second average threshold is used to distinguish steady pixels from transient pixels. 
 
     
     
       24. The system of  claim 23 , wherein the level detection module is further configured to perform a sub-pixel approximation for transient pixels, wherein the sub-pixel approximation is used in pixel alignment between the transmitter and the receiver. 
     
     
       25. The system of  claim 21  further comprising a control module operatively coupled with the light source and the ECC module, wherein the control module includes a counter which counts a quantity of instances in which error correction by the ECC module occurred, and wherein the control module is configured to at least one of increase and decrease an output power of the light source based on that quantity of error correction instances.