Thresholding of image diffences maps using first and second two-dimenstional array wherein respective euler number is determined

• US 8,239,435 B2
• Filed: 11/04/2008
• Issued: 08/07/2012
• Est. Priority Date: 11/04/2008
• Status: Expired due to Fees

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Miceli, Sean
• Primary Examiner(s): Peyton, Tammara
• Application Number:
  US12/264,781
• Publication Number:
  US 20100115016A1
• Time in Patent Office: 1,372 Days
• Field of Search: 708/308, 382/188, 382/149, 382/190, 382/276
• US Class Current: 708/308
• CPC Class Codes: G06V 10/28 Quantising the image, e.g. histogram thresholding for discrimination between background and foreground patterns

Abstract

Computer-readable media having corresponding apparatus embodies instructions executable by a computer to perform a method comprising: receiving a first array; generating a plurality of second arrays based on the first array, wherein each of the second arrays is generated using a different threshold number, and wherein each entry of the second arrays indicates whether a corresponding entry in the first array exceeds the respective threshold number; generating a first vector, wherein each entry in the first vector represents a number of connected components for a respective one of the second arrays; generating a second vector based on the first vector, wherein each entry of the second vector represents a variance of a plurality of entries, including a corresponding entry, of the first vector; generating a third vector, comprising filtering the second vector; and selecting, based on the third vector, one of the threshold numbers, of the second arrays or both.

Claims

1. Non-transitory computer-readable media embodying instructions executable by a computer to perform a method of thresholding an image difference map comprising:

receiving a first two-dimensional array representing an image difference map;

generating a plurality of second two-dimensional arrays based on the first two-dimensional array, wherein each of the second two-dimensional arrays is generated using a different threshold number, and wherein each entry of the second two-dimensional arrays indicates whether a corresponding entry in the first two-dimensional array exceeds the respective threshold number;

generating a first vector, wherein each entry in the first vector represents a number of connected components for a respective one of the second two-dimensional arrays;

generating a second vector based on the first vector, wherein each entry of the second vector represents a variance of a plurality of entries, including a corresponding entry, of the first vector;

generating a third vector, comprising filtering the second vector; and

selecting, based on the third vector, at least one of

one of the threshold numbers; and

one of the second two-dimensional arrays; and

wherein

determining the number of connected components for each of the second two-dimensional arrays comprises;

determining a respective Euler number for each of the second two-dimensional arrays.

2. The non-transitory computer-readable media of claim 1, wherein generating a first vector comprises:

determining the respective number of connected components for each of the second two-dimensional arrays.

3. The non-transitory computer-readable media of claim 1, wherein filtering the second vector comprises:

applying a median absolute deviation filter to the second vector.

4. The non-transitory computer-readable media of claim 1:

wherein the first two-dimensional array represents a difference map for a plurality of images.

5. An apparatus for thresholding an image difference map comprising:

an input module to receive a first two-dimensional array representing an image difference map;

a threshold module to generate a plurality of second two-dimensional arrays based on the first two-dimensional array, wherein each of the second two-dimensional arrays is generated using a different threshold number, and wherein each entry of the second two-dimensional arrays indicates whether a corresponding entry in the first two-dimensional array exceeds the respective threshold number;

a count module to generate a first vector, wherein each entry in the first vector represents a number of connected components for a respective one of the second two-dimensional arrays;

a variance module to generate a second vector based on the first vector, wherein each entry of the second vector represents a variance of a plurality of entries, including a corresponding entry, of the first vector;

a filter module to generate a third vector, comprising filtering the second vector; and

a select module to select, based on the third vector, at least one of

one of the threshold numbers; and

of the second two-dimensional arrays; and

wherein

the connected component module comprises;

an Euler module to determine a respective Euler number for each of the second two-dimensional arrays.

6. The apparatus of claim 5, wherein the count module comprises:

a connected component module to determine the respective number of connected components for each of the second two-dimensional arrays.

7. The apparatus of claim 5, wherein the filter module comprises:

a median absolute deviation filter module to apply a median absolute deviation filter to the second vector.

8. The apparatus of claim 5:

wherein the first two-dimensional array represents a difference map for a plurality of images.

9. An apparatus for thresholding an image difference map comprising:

input means for receiving a first two-dimensional array representing an image difference map;

threshold means for generating a plurality of second two-dimensional arrays based on the first two-dimensional array, wherein each of the second two-dimensional arrays is generated using a different threshold number, and wherein each entry of the second two-dimensional arrays indicates whether a corresponding entry in the first two-dimensional array exceeds the respective threshold number;

count means for generating a first vector, wherein each entry in the first vector represents a number of connected components for a respective one of the second two-dimensional arrays;

variance means for generating a second vector based on the first vector, wherein each entry of the second vector represents a variance of a plurality of entries, including a corresponding entry, of the first vector;

filter means for generating a third vector, comprising means for filtering the second vector; and

select means for selecting, based on the third vector, at least one of

one of the threshold numbers; and

one of the second two-dimensional arrays; and

wherein

the connected component means comprises;

Euler means for determining a respective Euler number for each of the second two-dimensional arrays.

10. The apparatus of claim 9, wherein the count means comprises:

connected component means for determining the respective number of connected components for each of the second two-dimensional arrays.

11. The apparatus of claim 9, wherein the filter means comprises:

median absolute deviation filter means for applying a median absolute deviation filter to the second vector.

12. The apparatus of claim 9:

wherein the first two-dimensional array represents a difference map for a plurality of images.