Image processing apparatus, image processing method, and computer-readable, non-transitory medium

An image processing method comprising:

• detecting a plurality of first edge pixels from an input image;
• detecting a straight line from the plurality of first edge pixels;
• classifying the plurality of first edge pixels into on-line edge pixels which are located within a predetermined distance from the straight line and non-on-line edge pixels which are not located within the predetermined distance;
• detecting second edge pixels located between two of the on-line edge pixels when there is any one of the non-on-line edge pixels between two of the on-line edge pixels;
• and
• determining, by a computer, whether the non-on-line edge pixel represents a document edge or not, based on whether or not the two on-line edge pixels are connected by the second edge pixels via the non-on-line edge pixel.

A computer-readable, non-transitory medium storing a computer program, wherein the computer program causes a computer to execute a process, the process comprising:

• detecting a plurality of first edge pixels from an input image;
• detecting a straight line from the plurality of first edge pixels;
• classifying the plurality of first edge pixels into on-line edge pixels which are located within a predetermined distance from the straight line and non-on-line edge pixels which are not located within the predetermined distance;
• detecting second edge pixels located between two of the on-line edge pixels when there is any one of the non-on-line edge pixels between two of the on-line edge pixels;
• and
• determining whether the non-on-line edge pixel represents a document edge or not, based on whether or not the two on-line edge pixels are connected by the second edge pixels via the non-on-line edge pixel.