The uncertainty of scanner illumination

Chengwu Cui

doi:10.1117/12.839613

18 January 2010 The uncertainty of scanner illumination

Chengwu Cui

Proceedings Volume 7529, Image Quality and System Performance VII; 75290J (2010) https://doi.org/10.1117/12.839613
Event: IS&T/SPIE Electronic Imaging, 2010, San Jose, California, United States

Abstract

Since typical document scanners are based on the principle of comparing the amount of light reflected from point of interest with that of a known surface, the reflectance of point of interest on the document measured by a scanner is therefore impacted by the reflectance of its neighboring region via multiple light reflections. The effect was referred to as the "integrating cavity effect". We investigate the effect by establishing an optical model with optical ray tracing. We demonstrated the effect by examining the illumination profile after accounting for multiple reflections off the document. The simulation shows that the impact is less significant for the slow scan direction as opposed to the fast scan direction. We identified that the platen glass can contribute just as much as the illumination assembly to the effect but the impact is much more localized. Further we demonstrated that the impact of the illumination assembly and the platen glass is independent from each other to a great degree and the impact of the illumination assembly to the illumination profile is equivalent to a convolution of the original document content with a Gaussian kernel of a considerable band width.

Citation Download Citation

Chengwu Cui "The uncertainty of scanner illumination", Proc. SPIE 7529, Image Quality and System Performance VII, 75290J (18 January 2010); https://doi.org/10.1117/12.839613

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