imhist: Multichannel Histogram of an Image

In swarm-lab/Rvision: Computer Vision Library for R

Multichannel Histogram of an Image

Description

imhist computes (or plots) the multichannel histogram of an Image object.

Usage

imhist(
  image,
  nbins = 257,
  range = c(0, 256),
  mask = NULL,
  plot = FALSE,
  col = c("blue", "green", "red", "black"),
  xlab = "Pixel value",
  ylab = "Counts",
  lty = 1,
  ...
)

Arguments

image	An Image object.
nbins	An integer indicating the number of bins of the histogram (default: 256).
range	The range of pixel values to include in the histogram (default: c(0, 256)). The lower boundary is inclusive but the higher one is exclusive.
mask	A single-channel (GRAY) 8-bit (8U) Image object with the same dimensions as image. This can be used to mask out pixels that should not be considered when calculating the histogram (pixels set to 0 in the mask will be ignored during the histogram calculation).
plot	A logical indicating whether to plot the histogram (default: FALSE).
col	A value or vector of any kind of R color specification compatible with col2rgb representing the color of the histogram for each image channel (default: c("blue", "green", "red", "black")).
xlab, ylab	Character strings for the axis labels (default: "Pixel value" for the x axis and "Counts" for the y axis).
lty	A vector of line types, see par.
...	Further arguments passed to matplot.

Value

If plot=FALSE, the function returns a m x n matrix, with m = nbins and n equal to the number of channels in the image + 1. The first column corresponds to the bin values. If plot=TRUE, the function plots the histogram and returned the aforementioned matrix silently.

Author(s)

Simon Garnier, [e-mail]

See Also

Image

Examples

balloon <- image(system.file("sample_img/balloon1.png", package = "Rvision"))
imhist(balloon, plot = TRUE)

swarm-lab/Rvision documentation built on Aug. 4, 2024, 2:29 p.m.