GLCM {agrifeature}

Gray Level Co-occurrence Matrix(GLCM).

Description

This function calculate Gray Level Co-occurrence Matrix(GLCM), which can be used to describe texture of the image. The default parameters is distance = 1, angle = 0, gray level = 8

Usage

GLCM(x, d = 1, angle = 0, ngray = 8, grayscale = c(0,255), symmetric = TRUE, prob = FALSE)

Arguments

x

A numeric matrix.

d

an integer value, the distance between the current pixel, and the pixel to which it is compared.

angle

one of "0", "45", "90" or "135", the pixel to which the current pixel is compared.

ngray

an integer value, the number of gray levels to use in calculate GLCM.

grayscale

a vector which contain c(min,max) to set the range of value , if NULL grayscale will be set into the min and max value in x.

symmetric

Logical value, if TRUE (default) the matrix will be turn into a symmetric GLCM.

prob

Logical value, if TRUE (default) the matrix will be normalized such that the sum of it's components is 1.

Value

A GLCM with dimension ngray*ngray table. Each column and row represent a gray level in the image matrix.

References

Hall-Beyer, M. (2000). GLCM texture: a tutorial. National Council on Geographic Information and Analysis Remote Sensing Core Curriculum, 3, 75.

Examples

# generate an image data matrix with range 0~255
set.seed(100)
m <- matrix(sample(0:255,64), nrow=8, ncol=8)

# calculate GLCM with defalut parameters
GLCM.m <- GLCM(m)

# calculate probability GLCM
GLCM.m.p <- GLCM(m,prob = TRUE)