rboxfilter

Contents: Description, Arguments, Usage, Examples, Images, Sub-Functions, Related Functions, Source Supported Under Version: >1.00 Current .dvrc Version: 1.02 Description Perform a running boxfilter on every xy plane of the data (band independent). rboxfilter() performs an individual boxfilter on every sub-section of the array defined by an x and y dimension. It then uses an overlap of half of the defined size to blend it with the next section of the data. This is done so there is no visible seam and the stretch is esentially "running" or changing over the whole data set. This process helps reduce the huge memory dependance of boxfilter allowing much larger images (>5x larger) to be processed using boxfilter(). While it is not as fast as boxfilter, it is still much faster than any of the convolove functions. Changing the x and y sizes will ultimately determine how local or regional features affect the stretch. Uses thm.sstretch as the stretching function. Arguments and Return Values Arguments: Accepts any numeric array Return Value: A stretched byte array Usage Syntax: rboxfilter(data = VAR, [ignore = FLOAT], [ysize = INT], [xsize = INT], [ksize = INT], [verbose = BOOL]) data - Any numeric array ignore - Ignore value of the black space. Default of -32768. ysize - Any integer for beaking up the data in the y direction. Default of 1000. xsize - Any integer for beaking up the data in the x direction. Default of 4000. ksize - boxfilter kernel size (currently only accepts square kernels). Default of 25. verbose - print the segment of the image that is being manipulated. Default is 0. Examples dv> a 829x3622x1 array of float, bsq format [12,010,552 bytes] The two methods below are equivalent and yeild the same results, but the second can be used for more memory efficient processing. dv> b = rsstretch(a,ysize=500,xsize=1000,ignore=-32768) 829x3622x1 array of byte, bip format [3,002,638 bytes] dv> b=rsstretch(data=a,ysize=500,xsize=1000,ignore-=32768) 829x3622x1 array of byte, bip format [3,002,638 bytes] Images The stretch of the left image is dominated by the canyon's huge difference in values (visible as contrast) and consequently the plains appear washed out. The stretch on the right is more consistent throughout normalizing the plains above the canyon to have a similar stretch as the canyon itself.

DavinciWiki Mini-Nav Bar Contents Functions Function Categories Common Procedures Glossary Download Davinci Change Log News Mailing List Contact Developers davinci-dev [AT] mars.asu.edu All other topics See navigation on the left Major Sub-Functions dim thm.sstretch create Related Functions rdcs rtilt rboxfilter data_manipulation.dvrc rboxfilter() Recent Library Changes Change Log Created On: 02-15-2006 Modified On: 01-31-2008