Hybrid mechanical and electronic deskew of scanned images in an image input terminal

An image input scanner for deriving an electronic representation of a document including a platen for supporting a document to be scanned;

• a scanning system including an array of photosensitive elements which produce an ordered set of electrical responses to sensed reflected light, said array supported parallel to said platen and acquiring data across the document in a fast scan direction, a light source providing illumination of a document supported on the platen, and an optical system directing and focusing light reflected from a document to the array;
• means supporting the scanning system and providing relative motion in a slow scan direction between the scanning system and the document;
• and a deskewing system sensing skew of a document and providing a deskewed representation thereof, said deskewing system comprising:
• a document skew detector measuring relative skew between the array and the document on the platen for scanning, and producing a measurement signal indicative thereof;
• said scanning system supported for rotation on the relative motion providing means, about an rotational axis perpendicular to said document;
• a drive means, for moving the scanning system in rotation about the rotational axis responsive to a control signal;
• a rotation controller, operative to control an amount of rotation of said scanning system in accordance with a skew measurement signal, whereby upon relative movement of the scanning system and the document in the slow scan direction, any skew effects in the direction of relative movement are removed from the electronic representation of the image;
• and
• said rotation controller also operative for shifting positions of derived electrical responses in the ordered set by a distance related to a position of the electrical response in the page, and the skew of the scanned document.