pixmap: channels-methods – R documentation

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channels-methods

Methods for Channel Manipulation

Description

Functions for manipulation and extraction of colors from channel-based pixmap formats. Methods for generic addChannels adds the color channels of a colored pixmap and returns a grey version. Methods for generic getChannels return numeric matrices or arrays containing the specified channels.

Usage

addChannels(object, coef = NULL)
  getChannels(object, colors = "all")

Arguments

`object`	Object of class `"pixmap"`.
`coef`	Coefficients for the color channels, a numeric vercot with as many elements as there are color channels in the pixmap. The default for RGB is `c(0.30, 0.59, 0.11)`, which makes a luminance-based conversion from color to grey.
`colors`	Character vector naming the color channels that shall be extracted. The default of `"all"` returns all channels simultaneously.

Author(s)

Friedrich Leisch

Examples

x <- pixmapRGB(rep(1:5, 3), nrow=4)
  plot(x)
  print(x)

  getChannels(x)
  getChannels(x, colors=c("red", "green"))

  y = addChannels(x)
  plot(y)
  print(y)

  ## extract only the red channel
  y = addChannels(x, coef=c(1,0,0))
  plot(y)

pixmap

Bitmap Images / Pixel Maps

v0.4-12

GPL-2

Authors

Roger Bivand, Friedrich Leisch and Martin Maechler

Initial release

2021-01-29