Performance evaluation of mail-scanning cameras
Umesh Rajashekar, Tony Tuan Vu, John E. Hooning, Alan Conrad Bovik · Journal of Electronic Imaging · 2010
Letter-scanning cameras (LSCs) form the front- end imaging systems for virtually all mail-scanning systems that are currently used to automatically sort mail products. As with any vision-dependent technology, the quality of the images generated by the camera is fundamental to the overall performance of the system. We present novel techniques for objective evaluation of LSCs using comparative imaging-a technique that involves measuring the fidelity of target images produced by a camera with reference to an image of the same target captured at very high quality. Such a framework provides a unique opportunity to directly quantify the camera's ability to capture real-world targets, such as handwritten and printed text. Noncomparative techniques were also used to measure properties such as the camera's modulation transfer function, dynamic range, and signal-to-noise ratio. To simulate real-world imaging conditions, application-specific test samples were designed using actual mail product materials.