Image sensors for establishing an image sharpness value

• US 8,941,744 B2
• Filed: 04/30/2008
• Issued: 01/27/2015
• Est. Priority Date: 04/30/2007
• Status: Expired due to Fees

• Current Assignee: STMicroelectronics Limited (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Limited (STMicroelectronics NV)
• Inventors: McLeod, Stuart, Duncan, Ed
• Primary Examiner(s): Berhan, Ahmed A
• Application Number:
  US12/112,227
• Publication Number:
  US 20080266406A1
• Time in Patent Office: 2,463 Days
• Field of Search: 348/208.99, 348/208.1, 348/208.6, 348/208.5, 348/345, 348/352, 348/349, 348/362, 348/222.1, 348/221.1
• 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

Abstract

A method of compensating for camera shake includes reading a sequential series of images from an image sensing array, establishing a sharpness value for each of the sequential series of images, and performing an image selection based upon each sharpness value. The sharpness value is calculated for each image of the sequential series thereof during the reading.

Claims

1. A method of compensating for camera shake comprising:

reading a sequential series of images from an image sensing array, using a controller;

storing image data from the image sensor array into a buffer;

calculating statistics on the image data, using the controller, to analyze a frequency variation across the image sensor array;

after the buffer is filled to a predetermined point, establishing a sharpness value for each image of the sequential series thereof based on the calculated statistics, using the controller; and

performing an image selection based upon each sharpness value, using the controller;

the sharpness value being calculated for each image during the reading.

2. The method of claim 1, wherein the image selection comprises selecting a single image.

3. The method of claim 2, wherein the single image is an image of the sequential series thereof having an optimal sharpness value.

4. The method of claim 1, wherein a result of the image selection is stored in a memory for presentation to a user.

5. The method of claim 1, wherein each image of sequential series thereof are ranked in order of their respective sharpness value and a plurality of images are presented to a user in ranked order.

6. The method of claim 5, wherein one or more of the plurality of images is selectable for permanent storage.

7. The method of claim 5, wherein the plurality of images are displayed in a composite thumbnail view on a display screen.

8. The method of claim 1, wherein a high sharpness value corresponds to a high proportion of high frequency content in the image.

9. The method of claim 1, wherein the image selection is performed by writing image data into a buffer and controlling contents of the buffer.

10. The method of claim 9, wherein once a new image is identified as having a sharpness value higher than a preceding image, the buffer is enabled to overwrite previous image data with new image data.

11. The method of claim 9, wherein an image compression step is performed prior to the writing image data into the buffer.

12. The method of claim 11, wherein a measure of a high frequency content is calculated based on a size of the image after the image compression step.

13. The method of claim 1, wherein the sequential series of images comprises between five and fifteen images taken over a time period between 100 and 1000 milliseconds.

14. The method of claim 1, wherein the sequential series of images comprises ten images taken over a period of 300-350 milliseconds.

15. An electronic device comprising:

receiver circuitry to receive a sequential series of images from an image sensing array during a single image capture event;

a buffer to store image data from the image sensor array;

a controller to

calculate statistics on the image data to analyze a frequency variation across the image sensor array, and

after the buffer is filled to a predetermined point, establish a sharpness value for each image of the sequential series thereof based on the calculated statistics, the sharpness value being established for each image during the single image capture event; and

output circuitry to output one or more images of the sequential series thereof.

16. The electronic device of claim 15, wherein said controller comprises image selection circuitry to select a single image from the sequential series thereof to be output.

17. The electronic device of claim 16, wherein said image selection circuitry selects the single image as an image identified as having an optimal sharpness value from among the sequential series thereof.

18. The electronic device of claim 15, wherein said controller comprises ranking circuitry to associate the sharpness value with each image of the sequential series thereof and to define a rank order, and wherein said output circuitry outputs all of the sequential series of images.

19. The electronic device of claim 15, wherein said receiver circuitry comprises a buffer to store part of an image.

20. The electronic device of claim 15, wherein said receiver circuitry, said controller, and said output circuitry define a co-processor operable with the image sensing array.

21. The electronic device of claim 15, wherein said receiver circuitry, said controller, and said output circuitry are integrated on a same chip as the image sensing array.

22. The electronic device of claim 15, wherein said electronic device comprises one of a digital still camera, a camera for use with a mobile phone, a mobile phone, a webcam, an optical mouse, and a barcode reader.

23. An electronic device, comprising:

an image sensing array;

a signal processing apparatus comprising

receiver circuitry to receive a sequential series of images from said image sensing array during a single image capture event,

a buffer to store image data from the image sensor array,

a controller to

calculate statistics on the image data to analyze a frequency variation across the image sensor array, and

after the buffer is filled to a predetermined point, establish a sharpness value for each image of the sequential series thereof based on the calculated statistics, the sharpness value being established for each image during the single image capture event, and

output circuitry to output one or more images of the sequential series thereof; and

a baseband processor arranged to receive an output from a signal processing apparatus.

24. The electronic device of claim 23, wherein said baseband processor is configured to initiate a request for an image or a series of images.

25. The electronic device of claim 24, wherein said baseband processor further comprises a baseband controller to rank the sequential series of images in terms of sharpness.

26. The electronic device of claim 25, wherein said baseband processor comprises a baseband controller to store a sharpest image of the sequential series thereof.

27. The electronic device of claim 23, wherein said electronic device comprises one of a digital still camera, a camera for use with a mobile phone, a mobile phone, a webcam, an optical mouse, and a barcode reader.