Real Time Digital Correction Of Acquisition Errors Applied To Solid State Scanners

T. R. Little

doi:10.1117/12.955711

8 December 1977 Real Time Digital Correction Of Acquisition Errors Applied To Solid State Scanners

T. R. Little

Proceedings Volume 0119, Applications of Digital Image Processing; (1977) https://doi.org/10.1117/12.955711
Event: 21st Annual Technical Symposium, 1977, San Diego, United States

Abstract

Capturing an image using a solid state scanner requires focusing the subject image on to the scanner array with some type of lens. Various kinds of degradations occur including Cos4 law, illumination non-uniformity, dust on the optical surfaces and flaws in the imaging array. The combined effects of all sources of image acquisition errors can result in serious cosmetic defects in the resulting image. Dramatic improvements in image quality can be achieved by multiplying the intensity value of each image pel by a correction factor: () Pout = Pin Pmax CFi Pout = corrected pel value Pin = pel value as captured Pmax = maximum possible pel intensity value CFi = correction factor for the ith position on the scan line The correction factors (CFi) are determined by capturing an image of a "standard white material" and calculating the average white value for each position on the scan line. The correction calculation requires multiply and divide operations which are too complicated to be performed at real time (21 million pels/second) in computer software. Therefore a 2-stage tabular lookup procedure has been implemented in bipolar RAM and PROM hardware. An additional feature of the approach is the possibility of performing any arbitrary intensity transformation by the substitution of a different PROM table.

Citation Download Citation

T. R. Little "Real Time Digital Correction Of Acquisition Errors Applied To Solid State Scanners", Proc. SPIE 0119, Applications of Digital Image Processing, (8 December 1977); https://doi.org/10.1117/12.955711

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