sstretch

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Description

Same as thm.sstretch

Sigma-stretch the data

The data is stretched according to the equation:

(data-avg)*(variance/stddev)+127

where:

  • 'variance' is a changeable variable but is defaulted to the value of 40
  • 'avg' is the average of the non-ignore value data
  • 'stddev' is the standard deviation of the non-ignore value data

Each band (XY plane) is stretched individually.

Arguments and Return Values

Arguments: A numeric array and an ignore value

Return Value: A byte bip 3-d array

Usage

Syntax: sstretch(data = VAL [, ignore = VAL] [, variance = VAL])

'ignore' - value to ignore in variance calculation. Default is -32768.

'variance' - An optionally designated variance of the stretch. Default is 40.

Examples

dv> a
320x650x10 array of short, bsq format [4,160,000 bytes]

dv> pic1=sstretch(a[,,1],var=10)
320x650x1 array of byte, bip format [208,000 bytes]

dv> display(pic1)

dv> pic2=sstretch(a[,,1])
320x650x1 array of byte, bip format [208,000 bytes]

dv> display(pic2)

dv> pic3=sstretch(a, variance=90)
320x650x10 array of byte, bip format [2,080,000 bytes]

dv> display(pic3[,,1])

Images

sstretch1.png pic1 sstretch2.png pic2 sstretch3.png pic3[,,1]

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Recent Core Changes

Modified On: 07-06-2009

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