hist Documentation

HIST - Create histogram of image
PROGRAMMER:TSTOEWE
Generates graphic histogram of frequency vs. DN for 8,16, or 32 bit
files.  This program counts each DN level within requested area
(SL,SS,NL,NS) and computes the mean, standard deviation and the skew
coefficient with and without zero level considered.  The program works
in the 8 bit range, so 16 and 32 bit data are converted to 8 bit with
the given MIN and MAX.

INPUT IMAGE FILE NAME

NONE

TITLE FOR HISTOGRAM

PRINT NORMALIZATION TABLE (Y,N)

N

MINIMUM DN TO CONVERT TO 8 BIT

0.

MAXIMUM DN TO CONVERT TO 8 BIT

255.

OUTPUT FILE NAME FOR HISTOGRAM
(NOT PRINT FILE)

NONE

STARTING LINE

1

STARTING SAMPLE

1

NUMBER OF LINES

0

NUMBER OF SAMPLES

0

LINE INCREMENT

1.

SAMPLE INCREMENT

1.

ADDITIONAL NOTES:

Parm	Description
FROM	The name of the disk file used to create a histogram. EX: DU5:IMAGE.PIC
TITLE	Label to be printed on top of histogram. The label should be some phrase which will distinguish this file from other files. It should include the data type (Viking, Landsat, etc.), the area the image covers (North Pole, Flagstaff, etc.) and the type of processing it's been through (Filter, Ratio, etc.). HIST will print out the file name, the number of lines and samples, the bit type, the MIN and MAX, the date run. The maximum number of characters is 60. EX: "VIKING PICNO=001A03 101X101 HPF"
NORM	This variable is only used if the data is 16 or 32 bit. If NORM=Y, the normalization table will be generated in the print file with your histogram. The normalization table is a table showing the input value in 16 or 32 bit and the 8 bit value it will be mapped to in the histogram. For instance, for a 16 bit image with a data range of 0-2550, a MIN=0 and MAX=2550 would result in a 10 time compression of the data to be shown on a histogram with only 255 levels. The normalization table would show how the compression would be made. If the table showed that 0 on the 16 bit data is mapped to 0 and 10 was mapped to 1, this would mean that all values less then 10, but greater than 0 would be mapped to 0.
MIN	This variable is only used for 16 or 32 bit data. Input DN less than or equal to MIN are mapped to zero. Since the histogram only shows 256 levels, 16 or 32 bit data must be converted to an 8 bit range to be shown on the histogram. The disk file is not changed in any way, only the histogram shows converted values. Input DN values greater than MIN and less than MAX are scaled as follows: DNOUT=(DN-MIN)*255/(MAX-MIN)
MAX	Applies only to 16 or 32 bit data. Input DN greater than or equal to MAX are mapped to 255. See MIN for more detail.
TO	If used, will create or add to a direct access file of histograms. This is not the print file. The histogram will be printed in a file called PRINT.PRT under your default directory.
LINC	Line increment. The default for most programs is 1.0 which will process each line of the image. LINC=2.0 will process every other line and the output image will have half as many lines as the input. LINC=.5 will process each line twice and the output image will have twice as many lines as the input.
NL	Number of lines. The default for all programs is 0 which will process all lines of the image.
NS	Number of samples. The default for all programs is 0 which will process all samples of the image.
SL	Starting line. The default is 1 for all programs which will start the processing with the first line or top of the image.
SS	Starting sample. The default is 1 for all programs which will start the processing with the first sample or left side of the image.
SINC	Sample increment. The default for most programs is 1.0 which will process each sample of the image. SINC=2.0 will process every other sample and the output image will have half as many samples as the input. SINC=.5 will process each sample twice and the output image will have twice as many samples as the input.