Browse Prior Art Database

TV Camera Shading Corrector

IP.com Disclosure Number: IPCOM000045444D
Original Publication Date: 1983-Mar-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Begnoche, N: AUTHOR

Abstract

This invention relates to a circuit for use in a closed-circuit television (TV) vidicon target camera, in order to correct the signal produced by the camera before it is converted to logic levels for computer analysis.

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TV Camera Shading Corrector

This invention relates to a circuit for use in a closed-circuit television (TV) vidicon target camera, in order to correct the signal produced by the camera before it is converted to logic levels for computer analysis.

Low frequency distortion of a video output signal is caused by image lighting variations and AGC compensation in the camera circuits. This distortion is called shading effect, and is as shown in Fig. 1(A). To remove this distortion from the video signal, the original signal is inverted, low-pass filtered and then detected. The resulting signal (Fig. 1(B)) is then added to the original signal, providing a flat signal which can then be converted into digital logic levels (Fig. 1(C)) by an analog to digital converter.

A circuit to accomplish the above distortion removal includes three operational amplifiers, and is as shown in Fig. 2.

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