Image processing method, image processing apparatus and image processing program

An image processing apparatus comprising:

• first pixel block sampling means for recursively sampling black pixel blocks and white pixel blocks from a binary image;
• tree structure creating means for creating tree structure data indicating a positional relation between the black pixel blocks and white pixel blocks sampled by said first pixel block sampling means;
• inverted image creating means for creating an inverted image by white-black-inverting the insides of black pixel blocks that can include inverted characters, of black pixel blocks included in said tree structure data;
• second pixel block sampling means for sampling white pixel block and black pixel blocks from the inverted image created by said inverted image creating means;
• and
• tree structure addition means for adding data regarding the white pixel blocks and black pixel blocks sampled by said second pixel block sampling means to corresponding nodes of said tree structure data.

A computer executable image processing program comprised of codes for making a computer perform:

• a first pixel block sampling step of recursively sampling black pixel blocks and white pixel blocks from a binary image;
• a tree structure creating step of creating tree structure data indicating a positional relation between the black pixel blocks and white pixel blocks sampled in said first pixel block sampling step;
• an inverted image creating step of creating an inverted image by white-black-inverting the insides of black pixel blocks that can include inverted characters, of black pixel blocks included in said tree structure data;
• a second pixel block sampling step of sampling white pixel block and black pixel blocks from the inverted image created in said inverted image creating step;
• and
• a tree structure addition step of adding data regarding the white pixel blocks and black pixel blocks sampled in said second pixel block sampling step to corresponding nodes of said tree structure data.

A storage medium including a computer readable image processing program, the image processing program comprised of codes for making a computer perform:

• a first pixel block sampling step of recursively sampling black pixel blocks and white pixel blocks from a binary image;
• a tree structure creating step of creating tree structure data indicating a positional relation between the black pixel blocks and white pixel blocks sampled in said first pixel block sampling step;
• an inverted image creating step of creating an inverted image by white-black-inverting the insides of black pixel blocks that can include inverted characters, of black pixel blocks included in said tree structure data;
• a second pixel block sampling step of sampling white pixel block and black pixel blocks from the inverted image created in said inverted image creating step;
• and
• a tree structure addition step of adding data regarding the white pixel blocks and black pixel blocs sampled in said second pixel block sampling step to corresponding nodes of said tree structure data.