Preventing blur caused by motion of the subject in a digital image
First Claim
1. A digital camera incorporating circuitry for prevention of blur caused by motion of a photographic subject, comprising:
- a multiplicity of photosensors arranged in an imaging array, each photosensor developing a first value proportional to the number of photons received by said sensor;
a photographic lens which projects an image onto the imaging array, wherein each photosensor in the imaging array is operatively connected to a circuit which is capable of calculating a second derivative with respect to time of the first value proportional to the number of photons received by said sensor; and
a programmable memory operatively connected to each circuit to store at least one time value for each photosensor corresponding to a length of exposure time for each photosensor, the length of exposure time for each photosensor connected to each circuit determined by the second derivative of the first value meeting a selected criteria which indicates movement was detected.
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Abstract
A digital camera has a sensor array which removes subject motion blur by monitoring the rate at which charge is collected by the individual sensors within the array during scene imaging. If the rate at which photons are striking the sensor varies, then the brightness of the image which the sensor is viewing must be changing. When a circuit built in to the sensor array detects that the image brightness is changing, the amount of charge collected is preserved and the time at which brightness change was detected is recorded. Each pixel corresponding to each sensor where exposure was stopped is adjusted to the proper exposure by linearly extrapolating the exposure the sensor did receive so that the pixel corresponding to the sensor has an intensity corresponding to the dynamic range of the entire image. The image sensing array will preferably be implemented as active-pixel sensor CMOS image sensors.
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Citations
14 Claims
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1. A digital camera incorporating circuitry for prevention of blur caused by motion of a photographic subject, comprising:
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a multiplicity of photosensors arranged in an imaging array, each photosensor developing a first value proportional to the number of photons received by said sensor;
a photographic lens which projects an image onto the imaging array, wherein each photosensor in the imaging array is operatively connected to a circuit which is capable of calculating a second derivative with respect to time of the first value proportional to the number of photons received by said sensor; and
a programmable memory operatively connected to each circuit to store at least one time value for each photosensor corresponding to a length of exposure time for each photosensor, the length of exposure time for each photosensor connected to each circuit determined by the second derivative of the first value meeting a selected criteria which indicates movement was detected. - View Dependent Claims (2, 3, 4, 5)
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6. A method of preventing image blur caused by motion of photographic subjects, comprising the steps of:
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forming an image on to an array of photosensors for a selected period of time;
for each sensor during said selected period of time, monitoring at least one value proportional to the rate at which photons are striking the sensor and calculating a second derivative of the at least one value;
for each sensor during said selected period of time, computing a second derivative of the at least one value, and comparing the second derivative with a criteria for determining motion; and
for each sensor during said selected period of time, upon the condition that motion is detected, because the second derivative meets the criteria for determining motion, recording a second value corresponding to the percentage of the selected period of time which has elapsed, and recording the at least one value. - View Dependent Claims (7, 8, 9)
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10. A method of preventing image blur caused by motion of photographic subjects, comprising the steps of:
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forming an image on to an array of photosensors for a selected period of time;
for each sensor during said selected period of time, monitoring a photon collection rate for the sensor;
for each sensor upon the condition that the photon collection rate varies more than a selected amount, recording a first value proportional to photons collected and recording a second value proportional to the percentage of the selected time which has elapsed; and
for each sensor wherein the photon collection rate does not vary more than a selected amount recording a third value proportional to the photons collected during the entire selected period of time. - View Dependent Claims (11, 12, 13, 14)
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Specification