Focus-based edge detection

• US 8,509,562 B2
• Filed: 08/28/2012
• Issued: 08/13/2013
• Est. Priority Date: 01/07/2009
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Pomerantz, Ori
• Primary Examiner(s): Akhavannik, Hadi
• Application Number:
  US13/596,800
• Publication Number:
  US 20120321179A1
• Time in Patent Office: 350 Days
• Field of Search: 382/275, 382/165
• US Class Current: 382/275
• CPC Class Codes: G06T 7/571 from focus

Abstract

A model generator computes a first image perimeter color difference value for each of a plurality of first pixels included in a first image that is captured using a first focal length, and selects one of the first image perimeter color difference values that exceeds a perimeter color difference threshold. Next, the model generator computes a second image perimeter color difference value for each of a plurality of second pixels included in a second image that is captured using a second focal length, and selects one of the second image perimeter color difference values that exceeds the perimeter color difference threshold. The model generator then determines that an edge is located at the first focal length by detecting that the selected first image perimeter color difference value is greater than the selected second image perimeter color difference value, and generates an image accordingly.

Claims

1. A computer-implemented method comprising:

computing a first image perimeter color difference value for a first pixel at a pixel location included in a first image that is captured using a first focal length, resulting in a first image perimeter color difference value;

computing a second image perimeter color difference value for a second pixel at the pixel location included in a second image that is captured using a second focal length that is different than the first focal length, resulting in a second image perimeter color difference value;

computing a third image perimeter color difference value for a third pixel at the pixel location included in a third image that is captured using a third focal length that is different than the first focal length and the second focal length, resulting in a third image perimeter color difference value;

identifying a number of local maximum color difference values at the pixel location using the first image perimeter color difference value, the second image perimeter color difference value, and the third image perimeter color difference value;

in response to identifying only one local maximum color difference value;

determining that a simple edge is located at the pixel location; and

generating a model based upon determining that the simple edge is located at the pixel location; and

in response to identifying two local maximum color difference values;

determining that a complex edge is located at the pixel location; and

generating the model based upon determining that the complex edge is located at the pixel location.

2. The method of claim 1 further comprising:

identifying a plurality of perimeter pixel pairs that correspond to the first pixel, wherein each of the perimeter pixel pairs lie on a contributing perimeter relative to the first pixel;

computing a pixel pair color difference value for each of the perimeter pixel pairs, resulting in a plurality of pixel pair color difference values;

identifying a largest pixel pair color difference value from the plurality of pixel pair color difference values; and

using the largest pixel pair difference value as the first image perimeter color difference value.

3. The method of claim 2 wherein the largest pixel pair color difference value corresponds to a perpendicular pixel pair included in the plurality of pixel pairs, the method further comprising:

wherein the perpendicular pixel pair includes a first perimeter pixel and a second perimeter pixel, the first perimeter pixel receiving a first light source within a first light dependence area, and the second perimeter pixel receiving a second light source within a second light dependence area, the first light source different than the second light source.

4. The method of claim 2 wherein, in response to the identifying only one local maximum color difference value, the method further comprises:

determining that the perpendicular pixel pair is perpendicular to the simple edge in response to identifying the largest pixel pair color difference value; and

utilizing information, during the model generation, resulting from determining that the perpendicular pixel pair is perpendicular to the simple edge.

5. The method of claim 2 wherein, in response to the identifying two local maximum color difference values, the method further comprises:

determining that the perpendicular pixel pair is perpendicular to the complex edge in response to identifying the largest pixel pair color difference value; and

utilizing information, during the model generation, resulting from determining that the perpendicular pixel pair is perpendicular to the complex edge.

6. The method of claim 1 wherein, in response to categorizing the edge as a complex edge, the method further comprises:

determining that one of the local maximum color difference values corresponds to the first image perimeter color difference value and that another one of the local maximum color difference values corresponds to the third image perimeter color difference value; and

utilizing the first focal length and the third focal length during the model generation by including a first facet as one part of the complex edge at the first focal length and including a second facet as another part of the complex edge at the third focal length.

7. A computer program product stored in a computer readable medium, comprising functional descriptive material that, when executed by an information handling system, causes the information handling system to perform actions that include:

computing a first image perimeter color difference value for a first pixel at a pixel location included in a first image that is captured using a first focal length, resulting in a first image perimeter color difference value;

computing a second image perimeter color difference value for a second pixel at the pixel location included in a second image that is captured using a second focal length that is different than the first focal length, resulting in a second image perimeter color difference value;

computing a third image perimeter color difference value for a third pixel at the pixel location included in a third image that is captured using a third focal length that is different than the first focal length and the second focal length, resulting in a third image perimeter color difference value;

identifying a number of local maximum color difference values at the pixel location using the first image perimeter color difference value, the second image perimeter color difference value, and the third image perimeter color difference value;

in response to identifying only one local maximum color difference value;

determining that a simple edge is located at the pixel location; and

generating a model based upon determining that the simple edge is located at the pixel location; and

in response to identifying two local maximum color difference values;

determining that a complex edge is located at the pixel location; and

generating the model based upon determining that the complex edge is located at the pixel location.

8. The computer program product of claim 7 wherein the information handling system further performs actions that include:

identifying a plurality of perimeter pixel pairs that correspond to the first pixel, wherein each of the perimeter pixel pairs lie on a contributing perimeter relative to the first pixel;

computing a pixel pair color difference value for each of the perimeter pixel pairs, resulting in a plurality of pixel pair color difference values;

identifying a largest pixel pair color difference value from the plurality of pixel pair color difference values; and

using the largest pixel pair difference value as the first image perimeter color difference value.

9. The computer program product of claim 8 wherein the largest pixel pair color difference value corresponds to a perpendicular pixel pair included in the plurality of pixel pairs, the information handling system further performing actions that include:

wherein the perpendicular pixel pair includes a first perimeter pixel and a second perimeter pixel, the first perimeter pixel receiving a first light source within a first light dependence area, and the second perimeter pixel receiving a second light source within a second light dependence area, the first light source different than the second light source.

10. The computer program product of claim 8 wherein, in response to the identifying only one local maximum color difference value, the information handling system further performing actions that include:

determining that the perpendicular pixel pair is perpendicular to the simple edge in response to identifying the largest pixel pair color difference value; and

utilizing information, during the model generation, resulting from determining that the perpendicular pixel pair is perpendicular to the simple edge.

11. The computer program product of claim 8 wherein, in response to the identifying two local maximum color difference values, the information handling system further performing actions that include:

determining that the perpendicular pixel pair is perpendicular to the complex edge in response to identifying the largest pixel pair color difference value; and

utilizing information, during the model generation, resulting from determining that the perpendicular pixel pair is perpendicular to the complex edge.

12. The computer program product of claim 7 wherein, in response to categorizing the edge as a complex edge, the information handling system further performing actions that include:

determining that one of the local maximum color difference values corresponds to the first image perimeter color difference value and that another one of the local maximum color difference values corresponds to the third image perimeter color difference value; and

utilizing the first focal length and the third focal length during the model generation by including a first facet as one part of the complex edge at the first focal length and including a second facet as another part of the complex edge at the third focal length.

13. An information handling system comprising:

one or more processors;

a memory accessible by at least one of the processors;

a nonvolatile storage area accessible by at least one of the processors;

a set of instructions stored in the memory and executed by at least one of the processors in order to perform actions of;

computing a first image perimeter color difference value for a first pixel at a pixel location included in a first image that is captured using a first focal length, resulting in a first image perimeter color difference value;

computing a second image perimeter color difference value for a second pixel at the pixel location included in a second image that is captured using a second focal length that is different than the first focal length, resulting in a second image perimeter color difference value;

computing a third image perimeter color difference value for a third pixel at the pixel location included in a third image that is captured using a third focal length that is different than the first focal length and the second focal length, resulting in a third image perimeter color difference value;

identifying a number of local maximum color difference values at the pixel location using the first image perimeter color difference value, the second image perimeter color difference value, and the third image perimeter color difference value;

in response to identifying only one local maximum color difference value;

determining that a simple edge is located at the pixel location; and

generating a model based upon determining that the simple edge is located at the pixel location; and

in response to identifying two local maximum color difference values;

determining that a complex edge is located at the pixel location; and

generating the model based upon determining that the complex edge is located at the pixel location.

14. The information handling system of claim 13 wherein the information handling system further performs actions that include:

identifying a plurality of perimeter pixel pairs that correspond to the first pixel, wherein each of the perimeter pixel pairs lie on a contributing perimeter relative to the first pixel;

computing a pixel pair color difference value for each of the perimeter pixel pairs, resulting in a plurality of pixel pair color difference values;

identifying a largest pixel pair color difference value from the plurality of pixel pair color difference values; and

using the largest pixel pair difference value as the first image perimeter color difference value.

15. The information handling system of claim 14 wherein the largest pixel pair color difference value corresponds to a perpendicular pixel pair included in the plurality of pixel pairs, the information handling system further performing actions that include:

wherein the perpendicular pixel pair includes a first perimeter pixel and a second perimeter pixel, the first perimeter pixel receiving a first light source within a first light dependence area, and the second perimeter pixel receiving a second light source within a second light dependence area, the first light source different than the second light source.

16. The information handling system of claim 14 wherein, in response to the identifying only one local maximum color difference value, the information handling system further performing actions that include:

determining that the perpendicular pixel pair is perpendicular to the simple edge in response to identifying the largest pixel pair color difference value; and

utilizing information, during the model generation, resulting from determining that the perpendicular pixel pair is perpendicular to the simple edge.

17. The information handling system of claim 14 wherein, in response to the identifying two local maximum color difference values, the information handling system further performing actions that include:

determining that the perpendicular pixel pair is perpendicular to the complex edge in response to identifying the largest pixel pair color difference value; and

utilizing information, during the model generation, resulting from determining that the perpendicular pixel pair is perpendicular to the complex edge.

18. The information handling system of claim 13 wherein, in response to categorizing the edge as a complex edge, the information handling system further performing actions that include:

determining that one of the local maximum color difference values corresponds to the first image perimeter color difference value and that another one of the local maximum color difference values corresponds to the third image perimeter color difference value; and

utilizing the first focal length and the third focal length during the model generation by including a first facet as one part of the complex edge at the first focal length and including a second facet as another part of the complex edge at the third focal length.