Apparatus and method of correcting for dark current in a solid state image sensor
AssigneeEastman Kodak Company
InventorsWayne E. Prentice, Stephen M. Coppola
Life of this patent
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Abstract
Apparatus and method of correcting for dark current in a solid state image sensor, include capturing an image with the image sensor to produce a digital image having pixel values; correcting the pixel values with a dark level correction value; employing a control system to adjust the dark level correction value to drive the number of pixels having values lower than a predetermined value chosen to represent dark scene content to a predetermined range.
Claims13
A method of correcting for dark current in a solid state image sensor, comprising the steps of:
- a) capturing an image with the image sensor to produce a digital image having pixel values;
- b) correcting the pixel values with a dark level correction value;
- and
- c) employing a control system to adjust the dark level correction value to drive the number of pixels having values lower than a predetermined value chosen to represent dark scene content to a predetermined range;
- and wherein the sensor captures a stream of digital images, and wherein the control system performs the steps of:
- c1) sampling a digital image from the stream of dark current corrected digital images;
- c2) generating a count of the number of pixel values in the sampled digital image that are less than a predetermined value;
- c3) generating a dark level correction value adjustment based on the pixel value count;
- and
- c4) applying the adjustment to the dark level correction value.
A method of correcting for dark current in a solid state image sensor, comprising the steps of:
- a) capturing a first image having a variable dark level;
- b) converting the first captured image to digital pixel values;
- c) processing the digital pixel values to determine the number of pixels having values below a dark level threshold pixel value;
- d) providing a dark correction value based on said number of pixels;
- and
- e) using the dark correction value to modify the digital pixel values of a second captured image.
Apparatus for correcting dark current in a solid state image sensor that produces digital images having pixel values, comprising:
- a) a dark level corrector for correcting the pixel values produced by the image sensor with a dark level correction value to produce dark level corrected pixel values;
- and
- b) a control system responsive to dark level corrected pixel values to adjust the dark level correction value to drive the number of pixels having values lower than a predetermined value chosen to represent dark scene content to a predetermined range;
- and wherein the sensor captures a stream of digital images, and wherein the control system includes:
- b1) means for sampling a digital image from the stream of dark current corrected digital images;
- b2) means for generating a count of the number of pixel values in the sampled digital image that are less than a predetermined value;
- b3) means for generating a dark level correction value adjustment based on the pixel value count;
- and
- b4) means for applying the adjustment to the dark level correction value.
Dependencies are inferred from the claim text.