Data type overflow using Band Math - NV5 Geospatial

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Last Post 06 Aug 2009 11:55 AM by anon

Data type overflow using Band Math

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anon

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06 Aug 2009 11:55 AM
Hi everybody, first of all sorry for mi English ;) I'm working with DN and I want to use this expression: 1.017DN -4.180 for band 1. I've thougth to use this: byte( 1.017b1-4.180) but I have the problem that if DN is, for example, 2, using that expresion it becames -2 --> 253, and want that the minimun value was 0 I've read ENVI help but I have no idea how to solve this. Thanks

MariM

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07 Aug 2009 11:31 AM
Try using IDL's BYTSCL to rescale the result in the parentheses to byte values. For example: ENVI> x=lindgen(10) ENVI> print, x 0 1 2 3 4 5 6 7 8 9 ENVI> print, bytscl(1.017x-4.180) 0 28 56 85 113 142 170 199 227 255 So you could use: bytscl(1.017b1-4.180)

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