Gamma ISP: Reference Manual

image_stat

ANSI-C program: image_stat.c

NAME
image_stat - Calculate mean, standard deviation and number of non-zero values for a rectangular region (float format)

SYNOPSIS
image_stat <data> <width> <roff> <loff> <nr> <nl> <report>

<data>	(input) text file containing list of names of co-registered data sets in column 1 (float)
<width>	image width in range pixels
<roff>	pixel offset to start (enter- for default: 0)
<loff>	line offset start (enter - for default: 0)
<nr>	number of range pixels (enter - for default: width - roff)
<nl>	number of lines to use (enter - for default: nl_file - loff)
<report>	output text file (keyword: value) format keywords: file, mean, stdev, total_samples, non_zero_samples, fractiont_valid)

EXAMPLE
image_stat 19990915.mli 2456 100 200 300 400 stat.out

calculates the image statistics in a specified region

DESCRIPTION image_stat is used to calculate the mean and standard deviation of float format data in a rectangular window specified on the command line. The upper left corner coordinates are specified by roff and loff parameters. The number of pixels across and lines down are specified by the nr and nl parameters. The program also counts the number of non-zero values in the window and calculates the percentage of non-zero values. The output is a report file that has keyword: value pairs as shown below:

data_file: 19990915.mli mean: 8.159940e-02 stdev: 1.958567e-02 total_samples: 120000 non_zero_samples: 120000 fraction_valid: 1.000000

One of the applications of this program is used to determine the number of valid samples and the average value and standard deviation in the overlap region of Sentinel-1 burst differential interferograms.

An example of running the program is shown below:

image_stat 19990915.mli 2456 100 200 300 400 stat.out

*** Calculate mean, standard deviation and number of non-zero values for a rectangular region (float format) *** *** Copyright 2014, Gamma Remote Sensing, v1.1 10-Dec-2014 *** data file: 19990915.mli line width (samples): 2456 number of lines in the file: 2687 range sample offset: 100 number of samples: 300 azimuth range offset: 200 number of lines: 400 output report file: stat.out data_file: 19990915.mli mean: 8.159940e-02 stdev: 1.958567e-02 total_samples: 120000 non_zero_samples: 120000 fraction_valid: 1.000000 user time (s): 0.000 system time (s): 0.000 elapsed time (s): 0.050