INFORMATION PROCESSING APPARATUS, CONTROL METHOD THEREFOR, AND PROGRAM

• US 20110103697A1
• Filed: 09/27/2010
• Published: 05/05/2011
• Est. Priority Date: 11/05/2009
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Ikeda, Kazuyo, Magai, Koichi, Shiiyama, Hirotaka
• Granted Patent: US 8,842,917 B2
• Time in Patent Office: Days
• US Class Current: 382/195
• CPC Class Codes: G06V 10/462 Salient features, e.g. scale invariant feature transforms [SIFT]

Abstract

An information processing apparatus includes: a calculation unit adapted to analyze an image and calculate an intermediate value; a setting unit adapted to set a feature extraction region in the image, using the intermediate value; and an extraction unit adapted to extract a local feature of the feature extraction region, reusing the intermediate value used by the setting unit.

Claims

1. An information processing apparatus comprising:

a calculation unit adapted to analyze an image and calculate an intermediate value;

a setting unit adapted to set a feature extraction region in the image, using the intermediate value; and

an extraction unit adapted to extract a local feature of the feature extraction region, reusing the intermediate value used by the setting unit.

2. The information processing apparatus according to claim 1, wherein the local feature of the image includes at least either a feature point of the image or a feature amount regarding the feature point of the image.

3. The information processing apparatus according to claim 1, wherein the calculation unit calculates a luminance gradient value for each pixel location in the image.

4. The information processing apparatus according to claim 3, wherein the setting unit sets the feature extraction region to a region where the luminance gradient value is greater than or equal to a predetermined threshold.

5. The information processing apparatus according to claim 1, wherein the calculation unit performs frequency conversion on the image and calculates a peak frequency coefficient in an image obtained by the frequency conversion as the intermediate value.

6. The information processing apparatus according to claim 5, wherein the setting unit sets the feature extraction region to a region where the peak frequency coefficient is greater than or equal to a predetermined threshold.

7. The information processing apparatus according to claim 1, wherein, after processing for setting the feature extraction region has started, the setting unit measures an area of an already-set feature extraction region and, if the area is greater than or equal to a predetermined value, stops the processing and sets the feature extraction region to an entire region of the image.

8. The information processing apparatus according to claim 1, wherein, if a predetermined period of time has elapsed after processing for setting the feature extraction region has started and before the processing is completed, the setting unit stops the processing and sets the feature extraction region to an entire region of the image.

9. The information processing apparatus according to claim 1, wherein the setting unit divides the image into a plurality of partial regions, selects the partial regions in random order, and sets the feature extraction region for each of the partial regions in the order of selection.

10. The information processing apparatus according to claim 1, further comprising:

a holding unit adapted to hold each local feature extracted by the extraction unit in association with the image.

11. The information processing apparatus according to claim 1, wherein

the image is an input image,

the information processing apparatus further comprising:

a retrieval unit adapted to retrieve an image similar to the input image by comparing a local feature of the input image with a local feature of each image held in the holding unit.

13. A program stored in a computer-readable medium and for causing a computer to serve as each unit of the information processing apparatus according to claim 1.

12. A control method for an information processing apparatus, comprising:

a calculation step, performed by a calculation unit, of analyzing an image and calculating an intermediate value;

a setting step, performed by a setting unit, of setting a feature extraction region in the image, using the intermediate value; and

an extraction step, performed by an extraction unit, of extracting a local feature of the feature extraction region, reusing the intermediate value used in the setting step.