Optical black calibration
First Claim
1. A method comprising:
- (a) reading first data from an image sensor in a preview mode, wherein the image sensor includes a plurality of rows of sensor elements, wherein the image sensor has a horizontally extending edge, a vertically extending edge, a valid area of sensor elements and a horizontally-extending shielded area of sensor elements, wherein the horizontally-extending shielded area extends horizontally between the valid area and the horizontally extending edge;
(b) reading second data from the horizontally-extending shielded area in a capture mode;
(c) using the second data read in (b) to determine an optical black value (OB value);
(d) reading third data from the valid area in the capture mode, wherein the OB value is determined in (c) before a substantial amount of third data is read from the valid area in (d), and wherein the third data in (d) is read from a first frame having a plurality of fields; and
(e) using the OB value determined in (c) to modify the third data read in (d) to obtain optical black adjusted data (OBAD), wherein the OB value is not changed until after third data has been read in (d) for each of the plurality of fields of the first frame from substantially all the sensor elements of the valid area.
3 Assignments
0 Petitions
Accused Products
Abstract
Preview mode low-resolution readouts occur, and then a shutter button on a camera is pressed, which causes an image sensor cleanout operation to occur. Following the cleanout, a high-resolution readout occurs. As rows of sensor values are read, the first rows are rows corresponding to a pre-defined horizontally-extending shielded area. There are no valid area sensor elements to either side of the horizontally-extending area. Data values read from the horizontally-extending area are used to determine optical black (OB) values that are then used to adjust the valid area values read out of the image sensor in that same frame. The same OB values are used throughout the adjusting of the valid area values of the entire frame. No values from the preview readouts are used in the OB value determination, so there is a clean break between the preview mode OB level and the high-resolution capture OB level.
20 Citations
23 Claims
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1. A method comprising:
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(a) reading first data from an image sensor in a preview mode, wherein the image sensor includes a plurality of rows of sensor elements, wherein the image sensor has a horizontally extending edge, a vertically extending edge, a valid area of sensor elements and a horizontally-extending shielded area of sensor elements, wherein the horizontally-extending shielded area extends horizontally between the valid area and the horizontally extending edge; (b) reading second data from the horizontally-extending shielded area in a capture mode; (c) using the second data read in (b) to determine an optical black value (OB value); (d) reading third data from the valid area in the capture mode, wherein the OB value is determined in (c) before a substantial amount of third data is read from the valid area in (d), and wherein the third data in (d) is read from a first frame having a plurality of fields; and (e) using the OB value determined in (c) to modify the third data read in (d) to obtain optical black adjusted data (OBAD), wherein the OB value is not changed until after third data has been read in (d) for each of the plurality of fields of the first frame from substantially all the sensor elements of the valid area. - View Dependent Claims (2, 3, 4, 5)
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6. A method comprising:
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(a) reading first data from an image sensor in a preview mode, wherein the image sensor is an integrated circuit that includes a plurality of rows of sensor elements, wherein the image sensor has a horizontally extending edge, a vertically extending edge, a valid area of sensor elements and a horizontally-extending shielded area of sensor elements, wherein the horizontally-extending shielded area extends horizontally between the valid area and the horizontally extending edge; (b) reading second data from the horizontally-extending shielded area in a capture mode; (c) using the second data read in (b) to determine an optical black value (OB value); (d) reading third data from the valid area in the capture mode, wherein the OB value is determined in (c) before a substantial amount of third data is read from the valid area in (d), and wherein the third data in (d) is read from a first frame having a plurality of fields; and (e) using the OB value determined in (c) to modify the third data read in (d) to obtain optical black adjusted data (OBAD), wherein the OB value is not changed until after third data has been read in (d) for each of the plurality of fields of the first frame from substantially all the sensor elements of the valid area, wherein the modifying of (e) involves; supplying the third data read from the valid area in (d) to a digital accumulator such that the digital accumulator outputs a digital value; using a digital filter to filter a stream of digital values output from the digital accumulator, the digital filter outputting a filter output value; storing the filter output value; and subtracting the filter output value from third data read from the valid area in (d). - View Dependent Claims (7)
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8. A method comprising:
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(a) reading first data from an image sensor in a preview mode, wherein the image sensor is an integrated circuit that includes a plurality of rows of sensor elements, wherein the image sensor has a horizontally extending edge, a vertically extending edge, a valid area of sensor elements, a horizontally-extending shielded area of sensor elements, and a vertically extending shielded area of sensor elements, wherein the horizontally-extending shielded area extends horizontally between the valid area and the horizontally extending edge; (b) reading second data from the horizontally-extending shielded area in a capture mode; (c) using the second data read in (b) to determine an optical black value (OB value); (d) reading third data from the valid area in the capture mode, wherein the OB value is determined in (c) before a substantial amount of third data is read from the valid area in (d), and wherein the third data in (d) is read from a first frame having a plurality of fields; (e) using the OB value determined in (c) to modify the third data read in (d) to obtain optical black adjusted data (OBAD), wherein the OB value is not changed until after third data has been read in (d) for each of the plurality of fields of the first frame from substantially all the sensor elements of the valid area; (f) reading data from the vertically-extending shielded area during a readout of the first frame of image data, and using the data read from the vertically-extending shielded area to determine a second optical black value (OB value); (g) reading a second frame of image data from the valid area of the image sensor in the capture mode; and (h) using the second OB value determined in (f) to modify the second frame of image data read in (g) to obtain second optical black adjusted data (OBAD).
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9. A method comprising:
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(a) reading first data from an image sensor in a preview mode, wherein the image sensor is an integrated circuit that includes a plurality of rows of sensor elements, wherein the image sensor has a horizontally extending edge, a vertically extending edge, a valid area of sensor elements and a horizontally-extending shielded area of sensor elements, wherein the horizontally-extending shielded area extends horizontally between the valid area and the horizontally extending edge; (b) reading second data from the horizontally-extending shielded area in a capture mode after performing an image sensor cleanout operation; (c) using the second data read in (b) to determine an optical black value (OB value); (d) reading third data from the valid area in the capture mode, wherein the OB value is determined in (c) before a substantial amount of third data is read from the valid area in (d), and wherein the third data in (d) is read from a first frame having a plurality of fields; and (e) using the OB value determined in (c) to modify the third data read in (d) to obtain optical black adjusted data (OBAD), wherein the OB value is not changed until after third data has been read in (d) for each of the plurality of fields of the first frame from substantially all the sensor elements of the valid area, wherein a low resolution frame of data is read out of the image sensor in (a), the low resolution frame being the last in a sequence of low resolution frames, and wherein the second and third data read in (b) and (d) is from a high resolution frame, and wherein the high resolution frame is the first high resolution frame of data to be read out of the image sensor after the low resolution frame that is read out in (a).
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10. An integrated circuit, comprising:
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means for determining an optical black value (OB value) using first data read from a horizontally-extending shielded area of an image sensor, wherein the image sensor includes a plurality of horizontally-extending rows of sensor elements, wherein the horizontally-extending shielded area extends between a horizontal edge of the image sensor and a valid area of the image sensor, wherein the first data is data from a first frame of image data, wherein the first frame is a high-resolution frame having a plurality of fields, wherein no data from a frame of image data other than the first frame is used in the determining of the OB value, and wherein the OB value is determined before a substantial amount of first frame data from the valid area of the image sensor is read from the image sensor; and a register that stores the same OB value throughout substantially the entire time that first frame data for each of the plurality of fields is read out from the valid area of the image sensor. - View Dependent Claims (11, 12, 13, 14, 15)
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16. An analog front end (AFE) integrated circuit, comprising:
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a first set of registers, the contents of which are usable by circuitry within the AFE to identify data read from a horizontally-extending shielded area of an image sensor, wherein the circuitry uses data read from the horizontally-extending shielded area during a first full resolution readout to determine an optical black (OB) value; a second set of registers, the contents of which are usable by the circuitry within the AFE to identify data read from a vertically-extending shielded area of the image sensor; and a third set of registers, the contents of which are usable by the circuitry within the AFE to identify data read from a valid area of the image sensor, wherein the image sensor has a horizontally-extending edge and a vertically-extending edge, wherein the horizontally-extending shielded area extends between the valid area and the horizontally-extending edge, wherein the vertically-extending shielded area extends between the valid area and the vertically extending edge, wherein the OB value is used to adjust image data read from the valid area during the first full resolution readout for a first frame having a plurality of fields, and wherein the OB value is determined before a substantial amount of the image data is read from the valid area and remains unchanged throughout substantially the entire time of the first full resolution readout. - View Dependent Claims (17, 18, 19, 20)
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21. A method, comprising:
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(a) powering up an image sensor; (b) reading first sensor data out of the image sensor, wherein the first sensor data is from a horizontally-extending shielded area of the image sensor, wherein the image sensor has a horizontally-extending edge; (c) using the first sensor data to determine an optical black value (OB value); (d) reading second sensor data out of the image sensor, wherein the second sensor data is from a valid area of the image sensor, wherein the horizontally-extending shielded area is at least partially between the valid area and the horizontally-extending edge; and (e) using the OB value to modify the second sensor data to obtain optical black adjusted data (OBAD), wherein both the first sensor data and the second sensor data are from a single frame of image data having a plurality of fields, wherein the single frame of image data is the first frame of image data read out of the image sensor after the powering up of (a), and wherein the OB value is determined before a substantial amount of the second sensor data is read from the valid area of the image sensor and remains unchanged throughout substantially the entire time that the second sensor data for each of the plurality of fields is read out from the valid area of the image sensor. - View Dependent Claims (22, 23)
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Specification