IDL Reference Guide: Procedures and Functions

NOISE_PICK

The NOISE_PICK function introduces noise into an image by picking randomly selected pixels to be replaced by a neighboring pixel from a random direction. The probability of replacing a pixel is controlled by a parameter which controls the amount of noise introduced into the image.

Syntax

Result = NOISE_PICK(Image [, Randomization] [, ITERATIONS=value] [, SEED=value])

Return Value

Result is an array of the same type and dimensions as Image.

Arguments

Image

A two dimensional or three dimensional array containing the input image. Two-dimensional arrays are treated as single channel images. For three-dimensional arrays the first dimension contains the color channels forming a pixel (Pixel Interleave).

Randomization

A floating-point scalar in the range 0.0-1.0 that specifies the probability of picking each pixel for replacement. 0.0 means there is no chance of replacement and 1.0 means that the pixel is always replaced. The default value is 0.5.

Keywords

ITERATIONS

Set this keyword to the number of times to apply the noise generator. Increasing the number of iterations increases the distance pixels can move.

SEED

Set this keyword to the seed value for the random number generator. This keyword is used in the same way as the SEED argument for RANDOMU.

Example

This example introduces noise to a test image:

; Read an image:  
image = BYTSCL(DIST(400))  
  
; Introduce noise to the image:  
image2 = NOISE_PICK(image, 0.9, ITER=30)  
  
; Display the images side by side:  
WINDOW, XSIZE=(SIZE(image))[1]*2, YSIZE=(SIZE(image))[2]  
TV, image, 0  
TV, image2, 1  

The resulting images appear as follows:

Figure 3-92: Image Before and After NOISE_PICK Application

Figure 3-92: Image Before and After NOISE_PICK Application

Version History

  IDL Online Help (March 06, 2007)