18 March 2008 Temporal-noise measurements of a CMOS camera used for image quality measurements
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Abstract
We have used a CMOS camera as multi-purpose instrument for measuring image quality of high-resolution LCD displays for use in medical diagnosis. The camera uses a Foveon sensor so that the RGB pixels are co-located making for simplified spatial sampling. In this presentation we examine the temporal-noise characteristics of the CMOS camera. We are using one of several LED's in an integrating sphere as the light source to provide the nominally uniform illumination for each experiment. In first experiments we place the camera sensor near to the opening of the integrating sphere without introducing an imaging lens in order to initially eliminate the characteristics of the lens. The capture parameters for the camera control software are set to give us as nearly raw data as possible. We suppress the native processing because our application is much different than the usual image-reproduction function. We capture sequences of images with the same illumination and same capture parameters and write them to TIFF files. The Matlab-based software we've written first pre-processes the images then calculates the pixel-wise mean and standard deviation over the sequence of frames. The calculation is repeated for each of the three (RGB) channels of the CMOS camera. These statistics are displayed as graytone images in three windows with the maxima and minima displayed in the title-bars. The short-term goal of the experiments is to prepare the way to compare the performance of cooled and un-cooled versions of the camera.
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Hans Roehrig, William J. Dallas, Gary R. Redford, "Temporal-noise measurements of a CMOS camera used for image quality measurements", Proc. SPIE 6913, Medical Imaging 2008: Physics of Medical Imaging, 69133D (18 March 2008); doi: 10.1117/12.773602; https://doi.org/10.1117/12.773602
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