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What is the recommended method for choosing Dark Object DN values?

April 26, 2017Dark DN method object recommended values

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What is the recommended method for choosing Dark Object DN values?

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While there are several ways to choose an appropriate Dark Object DN, the following outlines the method being used by the RSGIS Lab at USU. a) Load the imagery with DN values. b) Open ImageInfo in Imagine. c) Under Edit Menu, calculate statistics with an X and Y skip factor of 1, and set Ignore Value to 0. d) Display and examine the histogram. The DN choice for the Dark Object will be the lowest value at the base of the slope of the histogram. If the slope is gradual (i.e. contains very few (< 100 pixels of low DN values) these should be ignored, and the DN value chosen where slope of the histogram begins to increase more dramatically. In the figure below, an appropriate DN value for the Dark Object would be 39.