GNG

Description

Adds random Gaussian noise to an existing image.

Parameters

Name	Type	Caption	Length	Value range
FILE *	String	Input file name	1 - 192
DBOC *	Integer	Random Noise Layer	1 -
DBOW	Integer	Raster output window	0 - 4	0 -
MEAN *	Float	Mean value	1 - 1
STDV *	Float	Standard deviation	1 - 1	0 -
SEED	Integer	Random number seed (odd)	0 - 1	101 - 32767 Default: 1357
MONITOR	String	Monitor mode	0 - 3	ON, OFF Default: ON

* Required parameter

Parameter descriptions

FILE

Specifies the name of the input file that contains the layer(s) to be processed.

DBOC

Specifies the output channel(s) or layer(s) to receive the output results.

Duplicate channels are not allowed.

Ranges of channels or segments can be specified with negative values. For example, {1,-4,10} is internally expanded to {1,2,3,4,10}. When you are not specifying a range in this way, only 48 numbers can be specified explicitly.

DBOW

Specifies the raster window (Xoffset, Yoffset, Xsize, Ysize) to be processed. If DBOW is not specified, the entire layer is output by default. Xoffset and Yoffset define the upper-left starting pixel coordinates of the window. Xsize is the number of pixels that define the window width. Ysize is the number of lines that define the window height.

MEAN

Specifies the average gray-level value of Gaussian noise.

STDV

SEED

Specifies the random number seed.

This value must be an odd integer, between 101 and 32767.

MONITOR

The program progress can be monitored by printing the percentage of processing completed. A system parameter, MONITOR, controls this activity.

Available options are:

• ON: Turns the monitor ON (default)
• OFF: Turns the monitor OFF (recommended if running in batch or background mode)

Details

GNG generates Gaussian noise and adds it to a specified set of output image channels (DBOC) in the specified file. GNG is used to test the robustness of various image analysis algorithms, such as classifiers, filters, and transforms, in the presence of noise. The Gaussian noise has a specified mean (MEAN) and standard deviation (STDV), defined in gray-level units. When adding noise to existing image data, the mean is typically set to 0.

Gaussian noise can be added over a specified output window (DBOW), if desired.

A random number seed (SEED) must be specified and must be an odd number. This allows the generation of different Gaussian images (based on different seeds) having the same mean and standard deviation.

Example

Add random Gaussian noise (with a mean of 0 and 34% of the additive noise in the gray level range 0-3) to an existing image channel (1-4) from the file 'irvine.pix' in window 16,16,64,64.

EASI>FILE="irvine.pix"
EASI>DBOC=1,-4         ! add noise to channels 1-4
EASI>MEAN=0.0          ! noise has a mean of 0.0
EASI>STDV=3.0          ! 34% of the additive noise has a gray level of 0-3
EASI>SEED=1111         ! random number seed 111 used to generate noise
EASI>DBOW=
EASI>RUN GNG