Pixel averaging versus digitization using larger apertures: a comparison of the spatial resolution properties

Abstract
2K (2048 X 2500) or 1K (1024 X 1250) digitized chest film images can be generated by either direct digitization or converting a 4K (4096 X 5000) digitized film image by pixel averaging. In this paper, these two methods are compared for their implication on the resolution properties of the resulting images. A film image of the lead bar resolution pattern was used as the source of all digital images. Signal profiles of the bar pattern were studied to compare the pixel averaging and direct digitization methods. Based on this comparison, it was found that pixel averaging, when used with proper filtering, can be used to simulate direct digitization using larger (210/420) apertures and result in similar square wave response. Pixel averaging, however, can result in better square wave response when 2 to 1 or 4 to 1 straight averaging is used or a sharper kernel is used in pre-filtering.

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