R: Class Family "pixmap".

pixmap-class {pixmap} | R Documentation

## Class Family "pixmap".

### Description

The family `"pixmap"` (“pixel maps”) of classes provides methods for creating, plotting and converting bitmapped images in currently three different formats: RGB (`"pixmapRGB"`), grey (`"pixmapGrey"`)and indexed pixmaps (`"pixmapIndexed"`).

### Objects from the Class

Objects can be created by calls of the form `new("pixmap", ...)` or using the creator functions `pixmap` (similar for all child classes of name (`"pixmapXXX"`).

### Slots

`size`:

  Object of class `"integer"` and length 2 (number of rows and columns).

`cellres`:

  Object of class `"numeric"` and length 2 specifying the cell resolution of each pixel in user coordinates.

`bbox`:

  Object of class `"numeric"` and length 4, the coordinates of the bounding box (x bottom, y bottom, x top, y top).

`channels`:

  A character vector naming the channel slots of the object (`NULL` for indexed pixmaps).

`red`, `green`, `blue`:

  Only for class `"pixmapRGB"` with matrices specifying the red, green and blue channel of the picture.

`grey`:

  Only for class `"pixmapGrey"`, a matrix specifying the grey intensity (0=black, 1=white) of the picture.

`col`:

  Only for class `"pixmapGrey"`, a character vector with a map of color names.

`index`:

  Only for class `"pixmapIndexed"`, an integer matrix with codes from the color map.

### Details

Class `"pixmap"` specifies the basic geometry of a picture: the size in pixels together with information for an optional coordinate system, see `pixmap` for details.

Grey and indexed pixmaps are besically matrices (contained in the `grey` or `index` slot, respectively). The element `[1,1]` corresponds to the upper left corner as usual. For grey pixmaps the elements must be between 0 (black) and 1 (white). Indexed pixmaps have integer elements, each giving the index number corresponding to the palette specified in slot `"col"`. Colors are given using the usual R color strings (either names like `"red"` or hex values like `"#FF0000"`). Alternatively, a function to create a color palette can be specified, see `rainbow` or `heat.colors` for examples.

RGB pixmaps have three matrices for each of the three color channels. Elements of the matrices must be between 0 (=color off) and 1 (=color at maximum intensity).

Methods for coercion between all formats are available.

Class `"pixmapChannels"` is a helper parent class currently containing classes `"pixmapRGB"` and `"pixmapGrey"`.

### Author(s)

Friedrich Leisch

### See Also

`pixmap`

[Package pixmap version 0.4-11 Index]