Image processing apparatus, image processing system, image processing method and computer readable medium

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

• acquiring image data including a document region;
• storing in a storage a brightness of each pixel on a first main scan line outside the document region;
• correcting the brightness of each pixel on the first main scan line stored in the storage, in accordance with a brightness of pixels in a first part and the brightness of pixels in a second part on a second main scan line following the first main scan line;
• and
• detecting an edge point of the document region situated on the second main scan line in accordance with the difference between the corrected brightness of each pixel on the first main scan line and the brightness of each pixel on the second main scan line, respectively corresponding to each pixel on the first main scan line, wherein at least one of the first part and the second part on the second main scan line is outside of the document region.

An image processing system having an image reading apparatus and a computer apparatus that receives, via communication with the image reading apparatus, an image read by the image reading apparatus, comprising:

• a storage for storing, from the image data including a document region read by the image reading apparatus, a brightness of each pixel on a first main scan line outside the document region;
• a corrector for correcting the brightness of each pixel on the first main scan line stored in the storage, in accordance with the brightness of pixels in a first part and the brightness of pixels in a second part on a second main scan line following the first main scan line;
• and
• an edge point detector for detecting an edge point of the document region situated on the second main scan line, in accordance with a difference between the brightness of each pixel on the first main scan line corrected by the corrector and the brightness of each pixel on the second main scan line, respectively corresponding to each pixel on the first main scan line, wherein at least one of the first part and the second part on the second main scan line is outside of the document region.

An image processing method, comprising:

• acquiring image data including a document region;
• storing in a storage a brightness of each pixel on a first main scan line outside the document region;
• correcting the brightness of each pixel on the first main scan line stored in the storage, in accordance with the brightness of pixels in a first part and the brightness of pixels in a second part on a second main scan line following the first main scan line;
• and
• detecting an edge point of the document region situated on the second main scan line in accordance with a difference between the corrected brightness of each pixel on the first main scan line and the brightness of each pixel on the second main scan line, respectively corresponding to each pixel on the first main scan line, wherein at least one of the first part and the second part on the second main scan line is outside of the document region.