IMAGE SENSOR WITH INTEGRATED REGION OF INTEREST CALCULATION FOR IRIS CAPTURE, AUTOFOCUS, AND GAIN CONTROL

• US 20150379325A1
• Filed: 09/04/2015
• Published: 12/31/2015
• Est. Priority Date: 05/12/2008
• Status: Active Grant

• Current Assignee: Princeton Identity Inc.
• Original Assignee: SRI International, Inc.
• Inventors: Tinker, Michael, Ackerman, David Alan, Kolczynski, Raymond, Bergen, James
• Granted Patent: US 9,514,365 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06V 10/255 Detecting or recognising potential candidate objects based on visual cues, e.g. shapes
• CPC Class Codes: G06V 40/193 Preprocessing; Feature extraction
• CPC Class Codes: H04N 23/56 provided with illuminating means
• CPC Class Codes: H04N 23/673 based on contrast or high frequency components of image signals, e.g. hill climbing method
• CPC Class Codes: H04N 23/71 Circuitry for evaluating the brightness variation
• CPC Class Codes: H04N 23/74 by influencing the scene brightness using illuminating means

Abstract

An integrated circuit has an image sensor to receive at least one image comprising a plurality of pixels from a camera comprising a lens, a buffer communicatively connected to the image sensor for storing values associated with the plurality of pixels, and a comparator communicately connected to the buffer to locate and identify the iris of a subject, in which locating and identifying the iris of the subject is based on a location of each pixel in a brightest pixel set. A method for locating and identifying an iris in an image includes capturing at least one image of an illuminated subject, determining a brightness value for each of the plurality of pixels, determining a location corresponding to each pixel in a brightest pixel set, and identifying the iris in the at least one image based on the location of each pixel in the brightest pixel set.

Claims

1. An integrated circuit, comprising:

an image sensor configured to receive at least one image comprising a plurality of pixels from a camera comprising a lens;

a buffer communicatively connected to the image sensor for storing values associated with the plurality of pixels; and

a comparator communicately connected to the buffer configured to locate and identify the iris of a subject;

wherein locating and identifying the iris of the subject is based on a location of each pixel in a brightest pixel set.

2. The integrated circuit of claim 1, wherein locating and identifying the iris of the subject is also based upon on a pattern formed by the brightest pixel set.

3. The integrated circuit of claim 1, further comprising autofocus logic configured to adjust focus of the lens based upon a location of each pixel in the brightest pixel set.

4. The integrated circuit of claim 1, wherein the autofocus logic is further configured to repeatedly refocus the camera until a change in a highest pixel value among two successive scans is less than a predetermined threshold value.

5. The integrated circuit of claim 1, further comprising gain control logic configured to adjust the gain of the image sensor based upon the location of each pixel in the brightest pixel set.

6. The integrated circuit of claim 1, further comprising scan logic configured to scan the image sensor and send pixel values and addresses to the comparator.

7. The integrated circuit of claim 1, wherein the image sensor further comprises one of a CCD and a CMOS image sensor.

8. The integrated circuit of claim 1, wherein the brightest pixel set is associated with one or more specularities generated in the at least one image when illuminated by a plurality of illuminators.

9. An integrated circuit, comprising

an image sensor configured to capture an image of an illuminated subject;

scan logic connected to the image sensor, the scan logic configured to scan the image sensor and to send addresses and pixel values to a buffer;

a comparator to retrieve addresses and pixel values from the buffer and to determine a set of brightest pixels;

region of interest logic configured to receive the set of brightest pixels and locate a region of interest in the image and produce an output indicating the region of interest; and

autofocus logic to autofocus the camera based upon the region of interest.

10. The integrated circuit of claim 9, further comprising gain control logic configured to adjust the gain on the image sensor.

11. The integrated circuit of claim 9, further comprising capture control logic configured to cause the image sensor to repeat the image capture until a change in a highest value in the set of brightest pixels is less than a predetermined threshold.

12. The integrated circuit of claim 9, wherein the image sensor comprises one of a CCD and a CMOS image sensor.

13. The integrated circuit of claim 9, wherein the region of interest logic is configured to locate the region of interest based upon on a pattern formed by the brightest pixel set

14. A method for locating and identifying an iris in an image, the method comprising:

capturing at least one image of an illuminated subject, wherein the image comprises a plurality of pixels;

determining a brightness value for each of the plurality of pixels;

determining a location corresponding to each pixel in a brightest pixel set; and

identifying the iris in the at least one image based on the location of each pixel in the brightest pixel set.

15. The method of claim 14, wherein the brightest pixel set is associated with one or more specularities generated in the at least one image when illuminated by a plurality of illuminators.

16. The method of claim 14, wherein the system further comprises a buffer communicatively connected to the image sensor, and a comparator communicatively connected to the buffer, and wherein the method further comprises:

storing addresses and brightness of each of the plurality of pixels in the buffer;

sending a current stored value of a pixel to the comparator;

comparing with the comparator the stored value to a current smallest brightness value in the buffer, wherein if the current stored value is greater than the current smallest brightness value, then replacing the current smallest brightness value with the current stored value in the buffer; and

repeating the sending and comparing for each of the pixels in the image.

17. The method of claim 14, further comprising:

prior to storing addresses, translating linear addresses into row and column addresses for the image sensor;

scanning all pixels on the image sensor;

selecting from among the scanned pixels the addresses and brightness values corresponding to the brightest pixel set; and

storing the selected addresses and brightness values in the buffer.

18. The method of claim 14, further comprising sending the addresses of the pixels in the brightest pixel set from the buffer to the image sensor for output to a display.