Image reader that stores sets of luminance correction data corresponding to document a surface height

An image reader which reads a document surface of an open book-like document placed on a document platen in a face upward condition and detects a height of the document surface, said image reader comprising:

• a line sensor which reads the document surface, said line sensor extending in a main scanning direction and being moved in a sub-scanning direction;
• illuminating means for illuminating the document surface, said illuminating means having an illumination irregularity with respect to the main scanning direction;
• memory means for storing a plurality of sets of illuminance correction data with respect to the main scanning direction, each set corresponding to a height of the document surface;
• detecting means for detecting a height distribution of the document surface with respect to the sub-scanning direction;
• and
• correcting means for correcting the image data read by the line sensor using said illumination correcting data sets based on the height distribution.

A method of processing an image of an open book-like document placed on a document platen of an image reader in a face upward condition, the method comprising the steps of:

• memorizing a plurality of sets of illuminance correction data, each set corresponding to a height of the document surface;
• illuminating the document surface;
• detecting a height distribution of the document surface;
• reading the document and outputting image data;
• and
• correcting the image data using said luminance correction data sets based on the height distribution.

A method of processing an image of an open book-like document placed on a document platen of an image reader in a face upward condition, the method comprising the steps of:

• reading the document surface by moving a line sensor in a sub-scanning direction, said line sensor extending in a main scanning direction;
• illuminating the document surface with an illuminating light, wherein the illuminating light has an illumination irregularity with respect to the main scanning direction;
• storing a plurality of sets of illuminance correction data with respect to the main scanning direction, each set corresponding to a height of the document surface;
• detecting a height distribution of the document surface with respect to the sub-scanning direction;
• and
• correcting the image data read by the line sensor using said illumination correcting data sets based on the height distribution.