Image processing apparatus, image forming apparatus, image processing method and recording medium on which image processing program is recorded

An image processing method comprising:

• a step of inputting document image data corresponding to a document image of a document having been read, extracting candidates for page background pixels from the input document image data and determining a number of page background types;
• a step of extracting white pixels from the input document image data;
• and
• a step of determining a document size of the input document image data, based on the number of page backgrounds types determined, a page background density value which is the lowest density value in one or a plurality of page background areas determined to be page backgrounds, and a number of white pixels extracted,
• wherein, when it is determined that a plurality of page background types exists, the page background density value is compared with a predetermined white page background density threshold, and the document size is redetermined when the page background density value is greater than the white page background threshold,
• wherein the method further comprises a step of
• determining a number of pixels to be removed from candidates for page background pixels based on the redetermined document size, and
• wherein a page background is redetermined using a number of pixels in which the number of removal pixels are removed from the number of white pixels.

An image processing apparatus comprising:

• a page background determining section to which document image data corresponding to a document image of a document having been read is inputted and which extracts candidates for page background pixels from the input document image data and determines a number of page background types;
• a white pixel extracting section which extracts white pixels from the input document image data;
• and
• a document size determining section which determines a document size of the input document image data, based on the number of page backgrounds types determined by the page background determining section, a page background density value which is the lowest density value in one or a plurality of page background areas determined to be page backgrounds, and a number of white pixels extracted by the white pixel extracting section,
• wherein, when the page background determining section determines that a plurality of page background types exists, the page background density value is compared with a predetermined white page background density threshold, and the document size determining section redetermines the document size when the page background density value is greater than the white page background threshold,
• wherein the image processing apparatus further comprises a document type determining section which determines a document type based on the redetermined document size.

An image processing apparatus comprising:

• a page background determining section to which document image data corresponding to a document image of a document having been read is inputted and which extracts candidates for page background pixels from. the input document image data and determines a number of page background types;
• a white pixel extracting section which extracts white pixels from the input document image data;
• and
• a document size determining section which determines a document size of the input document image data, based on the number of page backgrounds types determined by the page background determining section, a page background density value which is the lowest density value in one or a plurality of page background areas determined to be page backgrounds, and a number of white pixels extracted by the white pixel extracting section,
• wherein, when the page background determining section determines that a plurality of page background types exists, the page background density value is compared with a predetermined white page background density threshold, and the document size determining section redetermines the document size when the page background density value is greater than the white page background threshold,
• wherein the image processing apparatus further comprises a color document determining section which performs the determination whether a document is a color document or a monochrome document based on the redetermined document size.

An image processing method comprising:

• a step of inputting document image data corresponding to a document image of a document having been read, extracting candidates for page background pixels from the input document image data and determining a number of page background types;
• a step of extracting white pixels from the input document image data;
• and
• a step of determining a document size of the input document image data, based on a number of page backgrounds types determined, a page background density value which is the lowest density value in one or a plurality of page background areas determined to be page backgrounds, and a number of white pixels extracted,
• wherein, when it is determined that a plurality of page background types exists, the page background density value is compared with a predetermined white page background density threshold, and the document size is redetermined when the page background density value is greater than the white page background threshold,
• wherein the method further comprises a step of determining a document type based on the redetermined document size.

An image processing method comprising:

• a step of inputting document image data corresponding to a document image of a document having been read, extracting candidates for page background pixels from the input document image data and determining a number of page background types;
• a step of extracting white pixels from the input document image data;
• and
• a step of determining a document size of the input document image data, based on a number of page backgrounds types determined, a page background density value which is the lowest density value in one or a plurality of page background areas determined to be page backgrounds, and a number of white pixels extracted,
• wherein, when it is determined that a plurality of page background types exists, the page background density value is compared with a predetermined white page background density threshold, and the document size is redetermined when the page background density value is greater than the white page background threshold,
• wherein the method further comprises a step of performing the determination whether a document is a color document or a monochrome document based on the redetermined document size.