A. Mansouri, F.S. Marzani, and P. Gouton
CCD calibration, temporal noise, Flat-Field acquisition, systematic noise reduction, multispectral imaging system
In this article, we describe in detail a method for calibrating a CCD- based camera. The calibration aims to remove both temporal and systematic noises introduced by the sensor, electronics, and optics after which we can correct the non-linearity of its response. For the non-linearity correction we use a simple and powerful approach consisting on a complementary approach between a polynomial ļ¬tting and an LUT based algorithm. The proposed methodology is accurate in the sense that it takes into account individual characteristics of each pixel. In each pixel, systematic noises are measured through acquiring offset images, thermal images, and Flat-Field images. A rigorous protocol for acquiring these images based on experimentation is established. The method to acquire Flat-Field image is novel and is particularly efficient in that it can correct all defects due to non-uniform pixel responses, vignettage, blemishes on optic and/or filters, and perhaps even illumination non-uniformity. We notice that such a methodology of calibration is particularly efficient in the case of an optical filter based multispectral imaging system, although it remains valid for any imaging system based on a CCD sensor.
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