with_ordered_dither: Dither image using a threshold dithering map

In ggfx: Pixel Filters for 'ggplot2' and 'grid'

Dither image using a threshold dithering map

Description

These filters reduces the number of colours in your layer and uses various threshold maps along with a dithering algorithm to disperse colour error.

Usage

with_circle_dither(
  x,
  map_size = 7,
  levels = NULL,
  black = TRUE,
  colourspace = "sRGB",
  offset = NULL,
  ...
)

with_custom_dither(
  x,
  map = "checks",
  levels = NULL,
  colourspace = "sRGB",
  offset = NULL,
  ...
)

with_halftone_dither(
  x,
  map_size = 8,
  levels = NULL,
  angled = TRUE,
  colourspace = "sRGB",
  offset = NULL,
  ...
)

with_ordered_dither(x, map_size = 8, levels = NULL, colourspace = "sRGB", ...)

Arguments

x	A ggplot2 layer object, a ggplot, a grob, or a character string naming a filter
map_size	One of 2, 3, 4, or 8. Sets the threshold map used for dithering. The larger, the better approximation of the input colours
levels	The number of threshold levels in each channel. Either a single integer to set the same number of levels in each channel, or 3 values to set the levels individually for each colour channel
black	Should the map consist of dark circles expanding into the light, or the reverse
colourspace	In which colourspace should the dithering be calculated
offset	The angle offset between the colour channels
...	Arguments to be passed on to methods. See the documentation of supported object for a description of object specific arguments.
map	The name of the threshold map to use as understood by magick::image_ordered_dither()
angled	Should the halftone pattern be at an angle or orthogonal

Value

Depending on the input, either a grob, Layer, list of Layers, guide, or element object. Assume the output can be used in the same context as the input.

See Also

Other dithering filters: with_dither()

Examples

library(ggplot2)

# Ordered dither
ggplot(faithfuld, aes(waiting, eruptions)) +
  with_ordered_dither(
    geom_raster(aes(fill = density), interpolate = TRUE)
  ) +
  scale_fill_continuous(type = 'viridis')

# Halftone dither
ggplot(faithfuld, aes(waiting, eruptions)) +
  with_halftone_dither(
    geom_raster(aes(fill = density), interpolate = TRUE)
  ) +
  scale_fill_continuous(type = 'viridis')

# Circle dither with offset
ggplot(faithfuld, aes(waiting, eruptions)) +
  with_circle_dither(
    geom_raster(aes(fill = density), interpolate = TRUE),
    offset = 29,
    colourspace = 'cmyk'
  ) +
  scale_fill_continuous(type = 'viridis')

ggfx documentation built on Aug. 22, 2022, 9:09 a.m.