Image processing apparatus, image processing method, and recording medium

An image processing method of estimating an inclination of an image processed in an image processing apparatus which detects an inclination of an image, comprising:

• an input step of inputting image information for expressing an image;
• an edge image generating step of dividing into blocks an image indicated by the image information inputted in the input step, calculating luminance values of pixels in each of the divided blocks, and generating a 1/N edge image based on a difference between a luminance value of a block of interest and a luminance value of a block adjacent to the block of interest;
• and
• an inclination detecting step of performing line scanning on the 1/N edge image, which has been generated in the edge image generating step, for every angle set beforehand, calculating an evaluation value based on a luminance of a pixel for every line on which the line scanning is performed, calculating a statistical value based on the evaluation value calculated for every line, and estimating the inclination of the image from the calculated statistical value.

A computer-readable recording medium on which a program of estimating an inclination of an image processed in an image processing apparatus which detects an inclination of an image is recorded, the program making a computer execute:

• an input step of inputting image information for expressing an image;
• an edge image generating step of dividing into blocks an image indicated by the image information inputted in the input step, calculating the luminance values of pixels in each of the divided blocks, and generating a 1/N edge image based on a difference between the luminance value of a block of interest and the luminance value of a block adjacent to the block of interest;
• and
• an inclination detecting step of performing line scanning on the 1/N edge image, which has been generated in the edge image generating step, for every angle set beforehand, calculating the evaluation value based on the luminance of a pixel for every line on which the line scanning is performed, calculating the statistical value based on the evaluation value calculated for every line, and estimating the inclination of the image from the calculated statistical value.