Image processing apparatus and image processing method

• US 7,986,838 B2
• Filed: 08/06/2008
• Issued: 07/26/2011
• Est. Priority Date: 08/07/2007
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Yoshimura, Hideyoshi, Ohira, Masakazu
• Primary Examiner(s): Tabatabai; Abolfazl
• Application Number:
  US12/187,153
• Publication Number:
  US 20090041360A1
• Time in Patent Office: 1,084 Days
• Field of Search: 382/125, 382/159, 382/162, 382/165, 382/181, 382/190, 382/198, 382/201, 382/219, 382/220, 701/28, 701/201, 702/82, 704/209, 707/749
• US Class Current: 382/181
• CPC Class Codes: G06F 18/2433 Single-class perspective, e.g. one-against-all classification; Novelty detection; Outlier detection
• CPC Class Codes: G06V 30/10 Character recognition
• CPC Class Codes: G06V 30/18143 Extracting features based on salient regional features, e.g. scale invariant feature transform [SIFT] keypoints
• CPC Class Codes: G06V 30/19173 Classification techniques
• CPC Class Codes: G06V 30/40 Document-oriented image-based pattern recognition
• CPC Class Codes: G06V 40/10 Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands

Abstract

The present invention provides an image processing apparatus capable of preventing deterioration of judgment accuracy when performing document matching process. To be more specific, when selecting feature points in the neighborhood of a target feature point, a predetermined number of feature points are selected after excluding a prespecified number of feature points in turn from the feature point nearest to the target feature point. For example, when the plurality of feature points are selected, the plurality of feature points, after excluding at least a feature point existing at a position nearest to the target feature point, are selected. Thereby, without increasing the amount of feature points for calculation of features (feature vectors), it is possible to prevent the deterioration of judgment accuracy.

Claims

1. An image processing apparatus which compares features extracted from inputted document image data with features of a reference image stored in advance to perform a judgment process on whether the inputted document image data is similar to the reference image stored in advance, wherein

when points indicating local characteristics of the image of the inputted document image data, which are determined from plurality of pixel values in the inputted document image data, are extracted and regarded as feature points, the features are values calculated on the basis of the positional relationship among plurality of feature points selected around a certain target feature point;

and

the image processing apparatus comprises a neighbor point selection section for, when selecting the plurality of feature points, selecting a predetermined number of feature points after excluding a prespecified number of feature points in turn from the feature point nearest to the target feature point.

2. The image processing apparatus according to claim 1, wherein, when selecting the plurality of feature points, the neighbor point selection section selects the plurality of feature points, excluding at least a feature point existing at a position nearest to the target feature point.

3. The image processing apparatus according to claim 1, wherein, when selecting the multiple feature points, the neighbor point selection section selects the multiple feature points, excluding at least a feature point existing at a position nearest neighbor to the target feature point and a feature point existing at the second neighbor position.

4. An image forming apparatus comprising:

the image processing apparatus according to claim 1; and

an image output section which forms an image according to inputted image data on a recording material.

5. A computer-readable recording medium in which a program for causing the image processing apparatus according to claim 1 to operate is recorded, the program being for causing a computer to function as the neighbor point selection section.

6. An image processing method for comparing features extracted from inputted document image data with features of a reference image stored in advance to perform judgment on whether the inputted document image data is similar to the reference image stored in advance, wherein

when points indicating local characteristics of the image of the inputted document image data, which are determined from plurality of pixel values in the inputted document image data, are extracted and regarded as feature points, the features are values calculated on basis of the positional relationship among plurality of feature points selected around a certain target feature point;

and

when the plurality of feature points are selected, a predetermined number of feature points are selected after excluding a prespecified number of feature points in turn from the feature point nearest to the target feature point.