X-ray onset detector for intraoral dental sensor
Techniques are provided for x-ray onset detection for an intraoral dental sensor. A methodology implementing the techniques according to an embodiment includes calculating a plurality of superpixel values for each of a plurality of rows of detector pixels of a sensor. Each of the superpixel values is based on a sum of pixel values of a set of pixels associated with the superpixel value, the set of pixels selected from the detection row of a current frame of the sensor. The method also includes calculating a difference between each of the superpixel values and a corresponding stored superpixel value generated from a previous sensor frame and determining if the differences exceed a superpixel threshold value. The method further includes incrementing a hit counter in response to the determination and generating a detection signal if the hit counter exceeds a hit count threshold, otherwise proceeding to process the next detection row.
1. An x-ray detector comprising:
an accumulator circuit configured to calculate a plurality of superpixel values, each of the superpixel values based on a sum of pixel values of a set of pixels associated with the superpixel value, the set of pixels selected from a detection row of a current frame of a sensor, wherein the set of pixels associated with each of the plurality of superpixel values is selected as a set of the pixels of the detection row that are interleaved with pixels associated with another of the plurality of superpixels values;
a comparator circuit configured to calculate a difference between each of the plurality of superpixel values and a corresponding stored superpixel value generated from a previous frame of the sensor;
a thresholding circuit configured to determine if the differences exceed a superpixel threshold value and to increment a hit counter in response to the determination; and
a detection circuit configured to generate a detection signal in response to a determination that the hit counter exceeds a hit count threshold.
2. The x-ray detector of claim 1 , wherein the detection row is a first detection row, and the x-ray detector is configured to process a second detection row, of a plurality of detection rows, in response to a determination that the hit counter does not exceed the hit count threshold.
3. The x-ray detector of claim 2 , wherein the plurality of detection rows comprises eight detection rows.
4. The x-ray detector of claim 1 , wherein the plurality of superpixels comprises four superpixels and the hit count threshold is in the range of zero to three.
5. The x-ray detector of claim 1 , wherein the frame of the sensor comprises a number of non-detection rows in the range of 1000 to 2000, and the detection rows are selected to avoid impaired pixels.
6. The x-ray detector of claim 5 , wherein the detection rows are interleaved with the non-detection rows and the detection rows are distributed more densely near a central region of the sensor.
7. The x-ray detector of claim 1 , wherein the detection signal is employed to trigger an integration and readout of the values of the pixels of the detection rows and values of pixels of non-detection rows of the current frame of the sensor.
8. A computer program product including one or more non-transitory machine-readable mediums encoded with instructions that when executed by one or more processors cause a process to be carried out for intraoral x-ray detection, the process comprising:
calculating a plurality of superpixel values, each of the superpixel values based on a sum of pixel values of a set of pixels associated with the superpixel value, the set of pixels selected from a detection row of a current frame of a sensor, wherein selecting the set of pixels associated with each of the plurality of superpixel values as a set of the pixels of the detection row that are interleaved with pixels associated with another of the plurality of superpixels values;
calculating a difference between each of the plurality of superpixel values and a corresponding stored superpixel value generated from a previous frame of the sensor;
determining if the differences exceed a superpixel threshold value;
incrementing a hit counter in response to the determination; and
generating a detection signal in response to a determination that the hit counter exceeds a hit count threshold.
9. The computer program product of claim 8 , wherein the detection row is a first detection row, and the process further comprises repeating the process on a second detection row, of a plurality of detection rows, in response to a determination that the hit counter does not exceed the hit count threshold.
10. The computer program product of claim 9 , wherein the plurality of detection rows comprises eight detection rows.
11. The computer program product of claim 8 , wherein the plurality of superpixels comprises four superpixels and the hit count threshold is in the range of zero to three.
12. The computer program product of claim 8 , wherein the frame of the sensor comprises a number of non-detection rows in the range of 1000 to 2000 and the detection rows are interleaved with the non-detection rows and the detection rows are distributed more densely near a central region of the sensor.
13. The computer program product of claim 8 , wherein the process further comprises triggering an integration and readout of the values of the pixels of the detection rows and values of pixels of non-detection rows of the current frame of the sensor, in response to the detection signal.
14. A method for intraoral x-ray detection, the method comprising:
calculating, by a processor-based system, a plurality of superpixel values, each of the superpixel values based on a sum of pixel values of a set of pixels associated with the superpixel value, the set of pixels selected from a detection row of a current frame of a sensor;
selecting the set of pixels associated with each of the plurality of superpixel values as a set of the pixels of the detection row that are interleaved with pixels associated with another of the plurality of superpixels values;
calculating, by the processor-based system, a difference between each of the plurality of superpixel values and a corresponding stored superpixel value generated from a previous frame of the sensor;
determining, by the processor-based system, if the differences exceed a superpixel threshold value;
incrementing, by the processor-based system, a hit counter in response to the determination; and
generating, by the processor-based system, a detection signal in response to a determination that the hit counter exceeds a hit count threshold.
15. The method of claim 14 , wherein the detection row is a first detection row, and the method further comprises repeating the process on a second detection row, of a plurality of detection rows, in response to a determination that the hit counter does not exceed the hit count threshold.
16. The method of claim 14 , wherein the plurality of superpixels comprises four superpixels and the hit count threshold is in the range of zero to three.
17. The method of claim 14 , further comprising triggering an integration and readout of the values of the pixels of the detection rows and values of pixels of non-detection rows of the current frame of the sensor, in response to the detection signal.