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US 6,320,680 B1Granted
Stochastic scanning documents to change moire effects
AssigneeDigimarc Corporation
InventorGeoffrey B. Rhoads
Life of this patent
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AssigneeDigimarc Corporation
InventorGeoffrey B. Rhoads
Estimating the term…
An additional motion is introduced into a scanning operation. This additional motion is in addition to the motion that is inherent in any document scanning operation. For example, in a flatbed scanner a linear array of scanning devices is positioned across the document in a first or “x” direction and this array is moved across the document in a perpendicular or “y” direction. In a flatbed scanner the position of the scanning devices are fixed in the “x” direction. In a drum scanner a light beam moves across the document in an “x” direction and the document is moved in the “y” direction. The light reflected from the document is directed to a fixed photoreceptor. With the present invention an additional vibratory motion is introduced into the scanning process. With a flatbed scanner the array of detector devices is moved or vibrated. The vibratory motion can for example be in the “x” direction. With a drum scanner the photoreceptor is moved or vibrated. For example the photodetector can be moved or vibrated in the “x” direction. The amount and direction of the vibratory movement can vary up to about one half the distance between units in the scanner's resolution (i.e. one half a pixel). If one is trying to eliminate Moiré patterns the vibratory movement can be a pseudo random series of movements. If one is trying to introduce a special pattern into the document or to otherwise create special effects, various other type of motion can be used. Movement of the CCD array in a flatbed scanner or movement of the photoreceptor in a drum scanner can be done by a simple piezo electric transducer or by a simple mechanical cam.
In a scanner which scans documents by moving a linear array of detectors over a document in a first direction, at least some of the detectors in said array each covering a particular distance,
A scanner which includes a linear array of detector elements each of which generates output signals, at least some of said detector elements each having a width equal to a first value,
A scanner which includes a linear array of detector elements each of which generates output signals, the distance between center points of said detector elements being equal to a first value,
In a scanner adapted to scan documents by moving a linear array of charge coupled devices (CCDs) over a document in a first direction,
The method of scanning a document which consists of a series of rows of areas with a linear array of detectors,
In a scanner which scans documents by moving a linear array of detectors over a document in a first direction, each of said detectors covering a first distance, the improvement which comprises means for vibrating said linear array of detectors in a direction perpendicular to said first direction, said vibration being in accordance with a pseudo random pattern of motion, and generating an image from said detectors which has pixels values equal to said first distance, whereby Moiré patterns are reduced.
A flatbed scanner for documents, said scanner including
A method of scanning a document including
Dependencies are inferred from the claim text.