Browse Prior Art Database

CALIBRATION MECHANISM FOR A CVT IMAGE INPUT MODULE

IP.com Disclosure Number: IPCOM000025071D
Original Publication Date: 1983-Jun-30
Included in the Prior Art Database: 2004-Apr-04
Document File: 2 page(s) / 126K

Publishing Venue

Xerox Disclosure Journal

Abstract

In image input scanners, to assure continued image quality, periodic shading correction is used to compensate for the individual variations across the video raster. Shading correction is necessary due principally to the high and low frequency non-uniformity of the scanning array (such as, for example, a Charge Coupled Device or CCD) and to variations and the less than ideal performance of the scanner optical and illumination systems. Essentially, shading correction is accomplished by calibrating or adjusting the image signal or pixel output of the scanning array in accordance with a "correct" image output signal derived from a reference or calibration image. For this purpose, the calibration image is imaged periodically by a calibration/correction procedure.

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'EROX L DISCLOSURE JOURNAL

CALIBRATION MECHANISM FOR A CVT IMAGE INPUT MODULE William H. Bruce, Jr.

William Brant

Proposed Classification US. Cl. 358/163
Int. C1. H04n 5/14

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Volume 8 Number 3 May/June 1983 27 3

FIG 2

[This page contains 1 picture or other non-text object]

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CALIBRATION MECHANISM FOR A CVT IMAGE INPUT MODULE (Cont'd)

During normal scanning, the calibration target 12 is retracted so as to be out of the scanning array's viewing field. When it is desired to calibrate the system, solenoid 19 is energized retracting armature 18 thereof and rotating spool 15 in the clockwise direction shown by the solid line arrow of Figure 2. Clockwise rotation

array 9. Lamp 11 is energized concurrently to illuminate the calibration image on the underside of target 12 and scanning array 9 actuated to scan. The calibration image data obtained is placed in memory (not shown) and thereafter used to correct the image signal or pixel output of the scanning array 9.

In image input scanners, to assure continued image quality, periodic shading correction is used to compensate for the individual variations across the video raster. Shading correction is necessary due principally to the high and low frequency non-uniformity of the scanning array (such as, for example, a Charge Coupled Device or CCD) and to variations and the less than ideal performance of the scanner optical and illumination systems. Essentially, shading correction is accomplished by calibrating or adjusting the image signal or pixel output of the scanning array in accordance with a "correct" image output signal derived from a reference or calibration image. For this purpose, the calibration image is imaged periodically by a calibration/correction procedure.

The concept presented here relates to a system for mechanically introducing a calibration image in the form of a target 12 into the viewing field of the scanning array, it being understood that scanning of the calibration image must be performed in close proximity to the object plane in which the d...