Patent ID: 7778443

Claim:
An image input apparatus comprising: a transport apparatus operable to move a scene object in a predetermined transport direction; an illuminating unit including a light source for emitting a linear light beam toward the scene object being moved in the predetermined transport direction by the transport apparatus and a glass member for cutting off heat rays and ultraviolet rays from the light source and transmitting visible light rays; an imaging unit for imaging the scene object illuminated by the linear light beam in a linear field of view; a photoelectric sensor configured to detect the scene object with respect to the transport direction of the transport apparatus prior to the imaging; an area sensor positioned downstream of the photoelectric sensor with respect to the transport direction and configured to detect a height parameter of the scene object, an operation of the area sensor to detect the height parameter started at a timing according to the detection of the scene object by the photoelectric sensor; an auto-focusing apparatus configured to start auto-focusing the imaging unit at a timing determined according to the detection of the scene object by the photoelectric sensor, the auto-focusing performed for the imaging of the scene object; and further comprising a video signal processing unit including an image compensation unit configured to perform gradation compensation and illumination non-uniformity correction of data received from a CCD reading in a CCD reading direction light reflected off the scene object; the image compensation unit configured to perform for each pixel the gradation compensation and the illumination non-uniformity correction based on both a forward envelope signal and a reverse envelope signal, the forward envelope signal being a first smoothed out value generated based on a pixel value of an instant pixel and the pixel value for a first reference pixel immediately preceding in the CCD reading direction the instant pixel, the reverse envelope signal being a second smoothed out value based on the pixel value of the instant pixel and the pixel value of a second reference pixel immediately following in the CCD reading direction the instant pixel, wherein a linear stepping motor is operable to auto-focus the image input apparatus, and the auto-focusing is made with back-and-forth movement of a printed board on which a linear array CCD for monochromatic or color imaging of a photo-electric conversion unit is mounted, and wherein positioning is performed based on a restoration of the linear stepping motor to an origin when an inter-mail distance between adjacent mails is sufficient with respect to a positioning motion time inclusive of a time for restoration to the origin, and otherwise auto-focusing is made by causing relative movement of the stepping motor only by a difference of motion parameters based on a previous position.