Dynamic image adaption method for adjusting the quality of digital prints

• US 20040170303A1
• Filed: 02/28/2003
• Published: 09/02/2004
• Est. Priority Date: 02/28/2003
• Status: Active Grant

• Current Assignee: HID Global Corporation (Assa Abloy AB)
• Original Assignee: Cross Match Technologies Incorporated (Assa Abloy AB)
• Inventors: Cannon, Greg L.
• Granted Patent: US 7,164,440 B2
• Time in Patent Office: Days
• US Class Current: 382/115
• CPC Class Codes: G06V 10/993 Evaluation of the quality of the acquired pattern
• CPC Class Codes: G06V 40/13 Sensors therefor
• CPC Class Codes: G06V 40/1347 Preprocessing; Feature extraction
• CPC Class Codes: H04N 1/00002 Diagnosis, testing or measuring; Detecting, analysing or monitoring not otherwise provided for error detection, error correction or monitoring in digital computers or digital computer components G06F11/00
• CPC Class Codes: H04N 1/00037 Detecting, i.e. determining the occurrence of a predetermined state H04N1/00031 takes precedence
• CPC Class Codes: H04N 1/0005 in service, i.e. during normal operation
• CPC Class Codes: H04N 1/00063 using at least a part of the apparatus itself, e.g. self-testing
• CPC Class Codes: H04N 1/00084 Recovery or repair, e.g. self-repair
• CPC Class Codes: H04N 1/40056 Circuits for driving or energising particular reading heads or original illumination means H04N1/401, H04N1/407 take precedence

Abstract

A dynamic image adaptation system and method for adjusting the quality of digital prints. The system includes an illumination source that illuminates an imaging surface of a live scanner optical system, the live scanner optical system scanning a biometric object placed on the imaging surface, a camera for capturing the print image of the biometric object placed on the imaging surface, a memory that stores data generated in the system, and a controller that adaptively controls at least one of the illumination source or the camera to obtain the print image with the predetermined quality. The controller adaptively controls the camera and the illumination source by adjusting one or more of contrast, gain, and integration time for the camera, and illumination for the illumination source.

Claims

1. A method for adaptive control of a system used to produce a print image, comprising:

detecting an image;

identifying a print image region in the image;

generating a measured histogram of the print image region;

determining an energy value of the measured histogram;

generating a desired histogram based on the measured histogram;

determining an energy value of the desired histogram;

determining an adaptive control energy based on the energy of the measured histogram and the energy of the desired histogram; and

using the adaptive control energy to generate a set of control parameter values to adaptively control the live scanner system, such that a predetermined quality of the print image is produced.

2. The method of claim 1, further comprising the step of adaptively controlling at least one of a camera and an illumination source in the system using the adaptive control energy.

3. The method of claim 1, wherein said identifying a print image region step comprises evaluating groups of pixels in the image to determine a standard deviation between the pixels in each of the groups to identify a grouping with a largest standard deviation, wherein the grouping with the largest standard deviation is masked as the print image region.

4. The method of claim 1, wherein said identifying a print image region step comprises the step of determining a gray area within the image in a shape of one of a square.

5. The method of claim 1, wherein said identifying a print image region step comprises the step of determining a gray area within the image in a shape of one of a square. or a rectangle.

6. The method of claim 1, wherein said determining the energy value of the measured histogram comprises the step of using an integral function.

7. The method of claim 1, wherein said determining the energy value of the desired histogram comprises the step of using an integral function.

8. The method of claim 1, wherein said determining the adaptive control energy steps comprises determining a difference between the energy value of the measured histogram and the energy value of the desired histogram.

9. The method of claim 1, wherein the set of control parameters includes at least one of contrast, gain adjustment, illumination, and integration time.

10. The method of claim 1, further comprising the step of adjusting one or more values in the set of the control parameters values until a tolerance is met to produce the predetermined quality of the print image.

11. A system using adaptive control to produce a print image of a predetermined quality, the system comprising:

an illumination source that illuminates an imaging surface of a live scanner optical system, the live scanner optical system scanning a biometric object placed on the imaging surface;

a camera for capturing the print image of the biometric object placed on the imaging surface;

a memory that stores data generated in the system; and

a controller that adaptively controls at least one of the illumination source or the camera to obtain the print image with the predetermined quality.

12. The system of claim 11, wherein the controller uses a determined energy value based on the print image to perform the adaptive control of an intensity of each LED in the illumination source.

13. The system of claim 11, wherein the controller uses a determined energy level to perform the adaptive control of the camera by adjusting one or more of contrast, gain, and integration time.