Method for preventing blurring of a digital image by monitoring a rate of change of photon reception

• US 7,050,091 B2
• Filed: 06/25/2002
• Issued: 05/23/2006
• Est. Priority Date: 05/19/2000
• Status: Expired due to Fees

• Current Assignee: Damon L. Tull
• Original Assignee: Damon L. Tull
• Inventors: Tull, Damon L.
• Primary Examiner(s): HO, TUAN V
• Application Number:
  US10/176,700
• Publication Number:
  US 20020154232A1
• Time in Patent Office: 1,428 Days
• Field of Search: 348/208.99, 348/208.1, 348/208.4, 348/208.5, 348/208.6
• US Class Current: 348/208.6
• CPC Class Codes: H04N 23/68 for stable pick-up of the scene, e.g. compensating for camera body vibrations
• CPC Class Codes: H04N 23/6811 based on the image signal
• CPC Class Codes: H04N 23/683 performed by a processor, e.g. controlling the readout of an image memory
• CPC Class Codes: H04N 25/533 by using differing integration times for different sensor regions
• CPC Class Codes: H04N 25/77 Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components

Abstract

A method for preventing blurring of an image includes the steps of projecting an image onto a photosensor array comprising a plurality of photosensors, monitoring a value proportional to a number of photons received by each photosensor in the array; determining a second derivative of the monitored value for each photosensor at least once during exposure; comparing the second derivative to a threshold value that varies during exposure, and recording the monitored value and time at which the second derivative has exceeded the threshold.

Claims

1. A method for preventing blurring of an image comprising:

projecting an image onto an imaging array, the imaging array comprising a plurality of photosensors;

monitoring a value proportional to a number of photons received by each of the plurality of photosensors during at least a portion of an exposure;

determining a second derivative of the monitored value for each of the photosensors at least once prior to completion of the exposure;

comparing the second derivative to a threshold value, the threshold value varying during the exposure; and

recording the monitored value and a time at which the second derivative has exceeded the threshold.

2. The method of claim 1, wherein a separate threshold is calculated for each photosensor.

3. The method of claim 2, wherein the separate threshold for each photosensor varies as a function of an amount of light received during the exposure by the photosensor.

4. A method for preventing blurring of an image comprising:

illuminating an imaging array with an image, the imaging array comprising a plurality of photo sensors;

monitoring a value proportional to a number of photons received by each of the plurality of photosensors during at least a portion of an exposure;

determining a second derivative of the monitored value for each of the photosensors at least once prior to completion of the exposure;

comparing the second derivative to a threshold value, the threshold value varying during the exposure; and

recording the monitored value and a time at which the second derivative has exceeded the threshold.

5. The method of claim 4, wherein a separate threshold is calculated for each photosensor.

6. The method of claim 5, further comprising the step of calculating the separate threshold for the photosensor based on a number of photons received prior to the comparing step by the photosensor.