Image manipulation utilizing edge detection and stitching for fingerprint recognition

• US 9,342,725 B2
• Filed: 03/15/2013
• Issued: 05/17/2016
• Est. Priority Date: 06/29/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Vieta, William M., Westerman, Wayne C.
• Primary Examiner(s): Patel, Nirav G
• Application Number:
  US13/842,052
• Publication Number:
  US 20140003682A1
• Time in Patent Office: 1,159 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G06V 40/1335 Combining adjacent partial images (e.g. slices) to create a composite input or reference pattern; Tracking a sweeping finger movement

Abstract

An error correction method and a mobile communication device incorporating the error correction method. The error correction method begins with receiving fingerprint image information that includes a set of swatches. A first one of the received swatches is matched to a second one of the swatches at an edge. A measure of fingerprint image manipulation is determined responsive to an amount of processing to perform and an amount of fingerprint image error. Then the fingerprint image information is manipulated in response to an optimum value of the measure.

Claims

1. An error correction method, comprising:

receiving fingerprint image information including a set of swatches;

matching a first one of the swatches and a second one of the swatches at an edge;

determining a measure of fingerprint image manipulation responsive to an amount of individual swatch error and an amount of edge stitching error, the determining comprising;

determining the amount of individual swatch error that would be present before and after each one of a set of possible operations of manipulating the fingerprint image information; and

determining the amount of edge stitching error that would be present before and after each one of the set of possible operations of manipulating the fingerprint image information; and

manipulating the fingerprint image information based on one or more determined values of the measures.

2. The error correction method of claim 1, further comprising:

summing the amounts of individual swatch error and the amounts of edge stitching error for each of the possible operations of manipulating the fingerprint image information; and

selecting a possible operation of manipulating the fingerprint image information that has a minimum value for sum of the individual swatch error and the edge stitching error.

3. A mobile communication device, comprising:

a processor,

a touch screen communicatively coupled to the processor, the touch screen adapted to receive input through a user contacting or nearly contacting a surface of the touch screen; and

a fingerprint sensor communicatively coupled to the processor and to the touch screen, the fingerprint sensor adapted to acquire fingerprint image information for one or more fingers of the user as the user enters touch input through the touch screen, wherein the fingerprint image information includes a set of swatches;

wherein the processor is configured to;

at least match a first one of the swatches and a second one of the swatches at an edge;

determine a first signal to noise ratio for the first one of the swatches, the first signal to noise ratio corresponding to an amount of information missing from the first one of the swatches;

determine at least one measure of fingerprint image manipulation based on one or more other signal to noise ratios and an amount of processing time associated with each signal to noise ratio; and

manipulate the first one of the swatches based on a selected signal to noise ratio, the selected signal to noise ratio selected from the one or more other signal to noise ratios.

4. The mobile communication device of claim 3, wherein the processor is further configured to determine a third signal to noise for the second one of the swatches, the third signal to noise ratio corresponding to an amount of information missing from the second one of the swatches.

5. The mobile communication device of claim 4, wherein the processor is further configured to select a signal to noise ratio to maximize the signal to noise ratio for the fingerprint image and minimize an amount of processing time needed to substantially obtain the selected signal to noise ratio.

6. The mobile communication device of claim 3, wherein the selected signal to noise ratio comprises one of:

a target signal to noise ratio that is optimal for image processing and enrollment of the fingerprint image or

a minimal signal to noise ratio that is minimally acceptable for image processing and enrollment of the fingerprint image.

7. The mobile communication device of claim 6, wherein the processor is further configured to:

determine an amount of processing time associated with the target signal to noise ratio; and

determine an amount of processing time associated with the minimal signal to noise ratio.

8. The mobile communication device of claim 7, wherein the processor is further configured to:

compare the amount of processing time associated with the target signal to noise ratio to the amount of processing time associated with the minimal signal to noise ratio;

in the event that the amount of processing time associated with the target signal to noise ratio does not exceed the amount of processing time associated with the minimal signal to noise ratio by a predetermined amount, allocate the amount of processing time associated with the target signal to noise ratio to substantially obtain the target signal to noise ratio; and

in the event that the amount of processing time associated with the target signal to noise ratio exceeds the amount of processing time associated with the minimal signal to noise ratio by the predetermined amount, allocate only the amount of processing time associated with the minimal signal noise ratio to substantially obtain the minimal signal to noise ratio.

9. The mobile communication device of claim 3, wherein the processor is further configured to:

determine an amount of individual swatch error that would be present before and after each one of a set of possible operations of manipulating the fingerprint image information; and

determine an amount of edge stitching error that would be present before and after each one of the set of possible operations of manipulating the fingerprint image information.

10. The mobile communication device of claim 9, wherein the processor is further configured to

sum the amounts of individual swatch error and the amounts of edge stitching error for each of the possible operations of manipulating the fingerprint image information;

and

select a possible operation of manipulating the fingerprint image information that has a minimum value for sum of the individual swatch error and the edge stitching error.

11. An error correction method for fingerprint image processing, the method comprising:

receiving fingerprint image information including a set of swatches;

matching a first one of the swatches and a second one of the swatches at an edge;

examining one or more portions of the first one of the swatches and the second one of the swatches for artifacts;

determining a degree of correction to be applied to each individual portion of the first one and the second one of the swatches based on a degree of individual swatch errors for the first one of the swatches and the second one of the swatches and a degree of errors for edge stitching between the first one and the second one of the swatches, the determining comprising;

determining an amount of individual swatch error that would be present before and after each one of a set of possible operations of manipulating the first one and the second one of the swatches; and

determining an amount of edge stitching error that would be present before and after each one of the set of possible operations of manipulating the first one and the second one of the swatches; and

manipulating at least one of the first one and the second one of the swatches based on a particular value of the degree of correction.

12. The error correction method of claim 11, further comprising:

summing the amounts of individual swatch error and the amounts of edge stitching error for each of the possible operations of manipulating the first one and the second one of the swatches; and

selecting a possible operation of manipulating at least one of the first one and the second one of the swatches that has a minimum value for sum of the individual swatch error and the edge stitching error.