Title: Encoding and Decoding Sixel Images
Version: 0.0.4
Description: Provides a native R implementation for encoding and decoding 'sixel' graphics (https://vt100.net/docs/vt3xx-gp/chapter14.html), and a dedicated 'sixel' graphics device that allows plots to be rendered directly within compatible terminal emulators.
License: MIT + file LICENSE
Encoding: UTF-8
RoxygenNote: 7.3.3
Imports: png
Suggests: jpeg, magick
NeedsCompilation: yes
Packaged: 2026-01-15 18:57:27 UTC; fanix
Author: Weifan Lv [aut, cre]
Maintainer: Weifan Lv <lvweifan@pku.edu.cn>
Repository: CRAN
Date/Publication: 2026-01-21 19:10:02 UTC

Create SIXEL escape sequence for image file

Description

Create SIXEL escape sequence for image file. jpeg, png or magick packages are required to read image files. Image with alpha channel will be blended with the specified background color.

Usage

imgcat(
  path,
  ...,
  max.colors = 256,
  iter.max = 10,
  background = "white",
  file = ""
)

Arguments

path

character, path to a image file.

...

other positional arguments will be omitted.

max.colors

integer, max colors of the palette. The maximum is 256. This parameter will be passed to sixelEncode.

iter.max

integer, maximum number of iterations for k-means clustering. This parameter will be passed to sixelEncode.

background

character, background color to blend with for pixel with transparency. Default is "white".

file

A connection, or a character string naming the file to print to. This parameter will be passed to cat

Value

None (invisible 'NULL').

Examples

imgcat(system.file("img", "Rlogo.jpg", package="jpeg"))

Read a SIXEL image

Description

Reads an image from a SIXEL file into a raster array.

Usage

readSIXEL(source)

Arguments

source

character, name of the file to read from.

Value

A raster array with values ranging from 0 to 1. The array has dimensions (height, width, 3) where the third dimension represents the R, G, and B color channels.

Examples

# read a sample file
img <- readSIXEL(system.file("snake.six", package="rsixel"))

SIXEL graphics device

Description

A graphics device that outputs SIXEL sequences to the console when closed. This device wraps the png() device and encodes the output as SIXEL.

Usage

sixel(
  file = "",
  width = 480,
  height = 480,
  max.colors = 256,
  iter.max = 10,
  background = "white",
  ...
)

Arguments

file

A connection, or a character string naming the file to print to. This parameter will be passed to cat. Default is "" (stdout).

width

integer, width of the output image in pixels. Default is 480.

height

integer, height of the output image in pixels. Default is 480.

max.colors

integer, max colors of the palette. The maximum is 256. This parameter will be passed to sixelEncode. Default is 256.

iter.max

integer, maximum number of iterations for k-means clustering. This parameter will be passed to sixelEncode. Default is 10.

background

character, background color to blend with for pixel with transparency. Default is "white".

...

Additional arguments passed to png().

Value

The device number (invisible).

Examples

sixel()
plot(c(1, 2))
dev.off()

Decode SIXEL escape sequence to image data

Description

Parse a SIXEL escape sequence and convert it to a raster array.

Usage

sixelDecode(data)

Arguments

data

character, SIXEL escape sequence.

Value

A raster array with values ranging from 0 to 1. The array has dimensions (height, width, 3) where the third dimension represents the R, G, and B color channels.

Examples

# read sixel sequence
sixel_file <- system.file("snake.six", package="rsixel")
sixel_data <- readChar(sixel_file, file.info(sixel_file)$size)
img <- sixelDecode(sixel_data)

Create SIXEL escape sequence from image data

Description

Create SIXEL escape sequence from image data. Quantization is done by k-means clustering.

Usage

sixelEncode(image, max.colors = 256, iter.max = 10)

Arguments

image

a three dimensional RGB array with values ranging from 0 to 1.

max.colors

integer, max colors of the palette. The maximum is 256. Default is 256.

iter.max

integer, maximum number of iterations for k-means clustering.

Value

SIXEL escape sequence

Examples

img <- png::readPNG(system.file("img", "Rlogo.png", package="png"))
cat(sixelEncode(img, 4))