channels-methods: Methods for Channel Manipulation

In pixmap: Bitmap Images / Pixel Maps

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)

Example output

Warning message:
In rep(cellres, length = 2) : 'x' is NULL so the result will be NULL
Pixmap image
  Type          : pixmapRGB 
  Size          : 4x4 
  Resolution    : 1x1 
  Bounding box  : 0 0 4 4 

, , red

     [,1] [,2] [,3] [,4]
[1,] 0.00 1.00 0.75 0.50
[2,] 0.25 0.00 1.00 0.75
[3,] 0.50 0.25 0.00 1.00
[4,] 0.75 0.50 0.25 0.00

, , green

     [,1] [,2] [,3] [,4]
[1,] 0.25 0.00 1.00 0.75
[2,] 0.50 0.25 0.00 1.00
[3,] 0.75 0.50 0.25 0.00
[4,] 1.00 0.75 0.50 0.25

, , blue

     [,1] [,2] [,3] [,4]
[1,] 0.50 0.25 0.00 1.00
[2,] 0.75 0.50 0.25 0.00
[3,] 1.00 0.75 0.50 0.25
[4,] 0.00 1.00 0.75 0.50

, , red

     [,1] [,2] [,3] [,4]
[1,] 0.00 1.00 0.75 0.50
[2,] 0.25 0.00 1.00 0.75
[3,] 0.50 0.25 0.00 1.00
[4,] 0.75 0.50 0.25 0.00

, , green

     [,1] [,2] [,3] [,4]
[1,] 0.25 0.00 1.00 0.75
[2,] 0.50 0.25 0.00 1.00
[3,] 0.75 0.50 0.25 0.00
[4,] 1.00 0.75 0.50 0.25

Pixmap image
  Type          : pixmapGrey 
  Size          : 4x4 
  Resolution    : 1x1 
  Bounding box  : 0 0 4 4 

pixmap documentation built on Jan. 29, 2021, 5:08 p.m.