Image evaluation apparatus, image evaluation method, and computer program product

Patent metadata

Field	Value
Publication number	US-2016239984-A1
Application number	US-201615018986-A
Country	US
Kind code	A1
Filing date	Feb 9, 2016
Priority date	Feb 12, 2015
Publication date	Aug 18, 2016
Grant date	—

Abstract

According to an embodiment, an apparatus includes a calculator, an pixel evaluator, an accumulator, and an area evaluator. The calculator is configured to calculate a feature of an image for each pixel in image data. The pixel evaluator is configured to produce a score that evaluates the feature for each pixel. The accumulator is configured to calculate, for each pixel, a cumulative score obtained by accumulating all scores in an area including a minor angle formed by a half line in a first direction from the each pixel position and another half line in a second direction from the each pixel position. The area evaluator is configured to calculate an evaluation value that is a total of the scores in a quadrilateral area enclosed by two lines of the first direction and two lines of the second direction based on the cumulative scores at pixel positions at vertexes of the quadrilateral area.

First claim

What is claimed is:

1 . An image evaluation apparatus comprising:
a feature descriptor calculator configured to calculate a feature descriptor that indicates a feature of an image for each pixel position in image data; a pixel evaluator configured to produce a score that evaluates the feature descriptor for each pixel position in the image data; a score accumulator configured to calculate, for each pixel position in the image data, a cumulative score obtained by accumulating all scores in an area including a minor angle that is formed by a half line extending in a predetermined first direction from the each pixel position serving as a starting point and another half line extending in a predetermined second direction from the each pixel position; and an area evaluator configured to calculate an area evaluation value that is a total of the scores in a quadrilateral area enclosed by two lines in parallel with the first direction and two lines in parallel with the second direction on the basis of the cumulative scores at pixel positions at vertexes of the quadrilateral area.

2 . The apparatus according to claim 1 , wherein
the quadrilateral area has a first vertex, a second vertex located in an area including a minor angle formed by a half line that extends in the first direction from the first vertex serving as the starting point and another half line that extends in the second direction from the first vertex, a third vertex and a fourth vertex that differ from the first and the second vertexes, and the area evaluator calculates a value obtained by subtracting a second addition value from a first addition value as the area evaluation value, the first addition value being a sum of the cumulative score at the first vertex and the cumulative score at the second vertex, the second addition value being a sum of the cumulative score at the third vertex and the cumulative score at the fourth vertex.

3 . The apparatus according to claim 2 , wherein the score accumulator selects, one by one, pixels that are two-dimensionally arranged in a first arrangement direction and a second arrangement direction in the image data by raster scanning, and calculates, as the cumulative score at the selected pixel, a value obtained by subtracting the cumulative score at a third pixel from a sum of the score at the selected pixel, the cumulative score at a first pixel, and the cumulative score at a second pixel, the first pixel being just before the selected pixel in the first arrangement direction, the second pixel being just before the selected pixel in the second arrangement direction, the third pixel being just before the first pixel in the second arrangement direction.

4 . The apparatus according to claim 3 , wherein
the first direction is opposite to the first arrangement direction, and the second direction is opposite to the second arrangement direction.

5 . The apparatus according to claim 4 , wherein
the first arrangement direction is directed from right to left in a horizontal direction, and the second arrangement direction is directed from up to down in a vertical direction.

6 . The apparatus according to claim 1 , further comprising:
a cumulative score storage configured to store the cumulative score at each pixel position in the image data; and an area designator configured to designate the quadrilateral area, wherein the area evaluator reads out, from the cumulative score storage, the cumulative scores at the pixel positions at the vertexes of the quadrilateral area designated by the area designator, and calculates the area evaluation value.

7 . The apparatus according to claim 1 , wherein
the feature descriptor calculator calculates, as the feature descriptor, a vector including a plurality of values, and the pixel evaluator produces the score on the basis of a norm between the feature descriptor and a preliminarily registered identification vector.

8 . The apparatus according to claim 1 , wherein a total value of the feature descriptors in an area is an evaluation target.

9 . The apparatus according to claim 1 , further comprising a normalizer configured to normalize the area evaluation value by an area of the quadrilateral area.

10 . The apparatus according to claim 9 , further comprising:
a weight acquirer configured to acquire a weight of the feature descriptor for each pixel position in the image data; a weight accumulator configured to calculate, for each pixel position in the image data, a cumulative weight obtained by accumulating all of the weights in an area including a minor angle formed by a half line extending in parallel with the first direction from the each pixel position serving as the starting point and another half line extending in parallel with the second direction from the each pixel position; and an area weight calculator configured to calculate a weight total value obtained by summing the weights in the quadrilateral area on the basis of the cumulative weights at the pixel positions at the vertexes of the quadrilateral area, wherein the normalizer normalizes the area evaluation value by the cumulative weight.

11 . An image evaluation method, comprising:
calculating a feature descriptor that indicates a feature of an image for each pixel position in image data; producing a score that evaluates the feature descriptor for each pixel position in the image data; calculating, for each pixel position in the image data, a cumulative score obtained by accumulating all scores in an area including a minor angle that is formed by a half line extending in a predetermined first direction from the each pixel position serving as a starting point and another half line extending in a predetermined second direction from the each pixel position; and calculating an area evaluation value that is a total of the scores in a quadrilateral area enclosed by two lines in parallel with the first direction and two lines in parallel with the second direction on the basis of the cumulative scores at pixel positions at vertexes of the quadrilateral area.

12 . A computer program product comprising a computer-readable medium containing a program executed by a computer, the program causing the computer to execute:
calculating a feature descriptor that indicates a feature of an image for each pixel position in image data; producing a score that evaluates the feature descriptor for each pixel position in the image data; calculating, for each pixel position in the image data, a cumulative score obtained by accumulating all scores in an area including a minor angle that is formed by a half line extending in a predetermined first direction from the each pixel position serving as a starting point and another half line extending in a predetermined second direction from the each pixel position; and calculating an area evaluation value that is a total of the scores in a quadrilateral area enclosed by two lines in parallel with the first direction and two lines in parallel with the second direction on the basis of the cumulative scores at pixel positions at vertexes of the quadrilateral area.

Assignees

• Toshiba Kk

Inventors

• Watanabe Tomoki
• Kubota Susumu
• Ito Satoshi
• Nakai Tomohiro

Classifications

• G06V10/50 Primary

  by performing operations within image blocks; by using histograms, e.g. histogram of oriented gradients [HoG]; by summing image-intensity values; Projection analysis · CPC title

• G06F16/24578

  using ranking · CPC title

• G06K9/481

  Physics · mapped topic

• G06T7/602 Primary

  Physics · mapped topic

• G06K9/4642

  Physics · mapped topic