Xerox Corporation

Richard B Eaton

Jagdish C Tandon

David Jon Metcalfe

Scott L Tewinkle

Yungran Choi

A print verification method and apparatus verifies the integrity of information printed on a document. The information to be verified is printed on a document in a first color. Desired information is printed on the document in a second color which is different from the first color. The desired information is printed directly above the information printed in the first color. It is detected whether any of the information printed in the first color is exposed following printing of the desired information in the second color. If any of the information printed in the first color is detected to be exposed, an indication is made that improper printing has occurred. If, however, no information printed in the first color is exposed following printing of the desired information in the second color, it is verified that proper printing has occurred.

Method and apparatus for print verification

Sensor array architectures for both analog and digital sensor arrays adapted for single chip applications or abutment with other like arrays to form a composite scanning array, the architecture providing a sensor array in which the array video signal processing circuits, clock circuits, etc. are integrated onto the same chip as the sensor array itself and dark reference sensors are located in-line or apart from the image scanning sensors to avoid gaps in the scan line when several sensor arrays are assembled together.

Architecture for analog and digital image sensor arrays

Imaging quality is measured in an electronic input scanner using the scanner imaging processing electronics. A contrast transfer function (CTF) of an optical system in an electronic input scanner is measured to determine focus quality by scanning a test pattern of lines, extending generally parallel with the slow scan direction, with no relative motion between the scanning element and the test pattern. The output of the scanning process is directed through the device thresholding operation. A series of successive scan lines are produced in this manner, each line produced with a successively incremented threshold level applied. The output of the thresholding device is examined at a plurality of locations to determine maximum and minimum transition points associated with the variation of threshold levels. Upon detection of the maximum and minimum, CTF is calculated using the threshold transition values. Signal to noise ratio is measured similarly by scanning a test pattern having a uniform gray image. A series of successive scan lines are produced, each line with a successively incremented threshold level applied. Noise causes producing a non-uniform scan line. The noise is measured by examining the number of lines where a non-uniform output is produced. Upon detection of the first and last non-uniform lines, signal to noise ratio can be calculated. For both tests, the scan lines produced may be printed in a standard binary printer allowing a qualitative examination of the results.

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Rochester, NY, United States of America

Richard B Eaton