Optical module positioning method

An optical module positioning method for an image processing device, the image processing device comprising a scanning platform and an optical module, the scanning platform comprising a first region, a second region, a third region and a fourth region, the fourth region being arranged between the first region and the second region, the first region being arranged between the third region and the fourth region, an initial position being included in the third region, a length of the fourth region being larger than a length of the third region, the optical module positioning method comprising steps of:

• driving the optical module to perform a scanning operation to acquire a scanned image while the optical module is not moved;
• if a color value of a first end of the scanned image and a color value of a second end of the scanned image are in a first color range or a second color range, determining that the optical module is stayed in the third region;
• if the color value of the first end of the scanned image is in a third color range and the color value of the second end of the scanned image is in the second color range, determining that the optical module is stayed in the first region;
• if the color value of the first end of the scanned image is in the second color range and the color value of the second end of the scanned image is in a fourth color range, determining that the optical module is stayed in the second region;
• and
• if the color value of the first end of the scanned image and the color value of the second end of the scanned image are in the fourth color range, determining that the optical module is stayed in the fourth region.