Image processing apparatus, method therefor, and program

An image processing method of deciding a comparison position for performing similarity comparison between a comparison source image and a comparison destination image, comprising:

• a designation step of designating a block division count representing a division count for dividing an image;
• a dividing step of dividing each of the comparison source image and the comparison destination image into a plurality of blocks by the block division count designated in the designation step;
• a feature amount calculation step of calculating feature amounts of the comparison source image and the comparison destination image for each block divided in the dividing step;
• a similarity distance calculation step of calculating, on the basis of feature amounts of corresponding blocks in the comparison source image and the comparison destination image, a similarity distance between the comparison source image and the comparison destination image after comparison positions are shifted by using a plurality of types of position shifting patterns for shifting the comparison positions of the comparison source image and the comparison destination image;
• a position correction amount calculation step of calculating a position correction amount for correcting the comparison positions of the comparison source image and the comparison destination image that are used in performing next similarity comparison, on the basis of a size of the block and a position shifting pattern corresponding to a smallest similarity distance among similarity distances calculated in the similarity distance calculation step;
• a correction step of correcting the comparison positions of the comparison source image and the comparison destination image by the position correction amount;
• an executing step of, every time the position correction amount is calculated in the position correction amount calculation step, incrementing the block division count designated in the designation step, and recursively executing the steps from the dividing step to the correction step;
• a determination step of determining whether to end recursive processing;
• and
• a finalizing step of, when the recursive processing is to be ended on the basis of a determination result in the determination step, finalizing a comparison position at that time as final comparison positions of the comparison source image and the comparison destination image.

A computer program for implementing image processing of deciding a comparison position for performing similarity comparison between a comparison source image and a comparison destination image, comprising:

• a program code for a designation step of designating a block division count representing a division count for dividing an image;
• a program code for a dividing step of dividing each of the comparison source image and the comparison destination image into a plurality of blocks by the block division count designated in the designation step;
• a program code for a feature amount calculation step of calculating feature amounts of the comparison source image and the comparison destination image for each block divided in the dividing step;
• a program code for a similarity distance calculation step of calculating, on the basis of feature amounts of corresponding blocks in the comparison source image and the comparison destination image, a similarity distance between the comparison source image and the comparison destination image after comparison positions are shifted by using a plurality of types of position shifting patterns for shifting the comparison positions of the comparison source image and the comparison destination image;
• a program code for a position correction amount calculation step of calculating a position correction amount for correcting the comparison positions of the comparison source image and the comparison destination image that are used in performing next similarity comparison, on the basis of a size of the block and a position shifting pattern corresponding to a smallest similarity distance among similarity distances calculated in the similarity distance calculation step;
• a program code for a correction step of correcting the comparison positions of the comparison source image and the comparison destination image by the position correction amount;
• a program code for an executing step of, every time the position correction amount is calculated in the position correction amount calculation step, incrementing the block division count designated in the designation step, and recursively executing the steps from the dividing step to the correction step;
• a program code for a determination step of determining whether to end recursive processing;
• and
• a program code for a finalizing step of, when the recursive processing is to be ended on the basis of a determination result in the determination step, finalizing a comparison position at that time as final comparison positions of the comparison source image and the comparison destination image.