R: Methods for Channel Manipulation

channels-methods {pixmap} | R Documentation

## 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)

[Package pixmap version 0.4-11 Index]