## NAME

r.bitpattern

## DESCRIPTION

r.bitpattern performs bit pattern comparisons. The module can be used to pixelwise verify a satellite image for low quality pixels if a Quality Control Bit Index map is provided (e.g. as for MODIS sensor maps). The functionality is two-fold:

1. define position: set bit(s) to 1 which shall match, then convert this position pattern to integer, set pattern= parameter with that integer value
2. define pattern *value* which should be in that position: first bit pattern of value, convert to integer, set patval= parameter

If several bitpatterns have to be tested, the resulting maps can be used to exclude low quality pixel in the input satellite image using r.mapcalc (OR and NOT operators).

## EXAMPLE

1. define position:

       	xx xx 1x xx
       	binary: 1000 -> integer: 8 -> pattern=8

2. define value:

               Ex.: we want to check for 0 in that position
       	xx xx 0x xx
       	binary: 0000 -> integer: 0 -> patval=0
               if value can be arbitray (0/1), then assume 0 value

## SEE ALSO

r.mapcalc

## AUTHORS

Radim Blazek, Markus Neteler

Last changed: $Date: 2008-05-16 21:09:06 +0200 (Fri, 16 May 2008) $

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