Pngex

A library for generating PNG images.

Installation

If available in Hex, the package can be installed by adding pngex to your list of dependencies in mix.exs:

def deps do
  [
    {:pngex, "~> 0.1.0"}
  ]
end

Documentation can be generated with ExDoc and published on HexDocs. Once published, the docs can be found at https://hexdocs.pm/pngex.

Generates images

Pixel data

Use binary, list of integers or list of tuples to express pixel data of the image.

Binary

List of integers

List of tuples

Examples

RGB

Prepare bitmap image data

bitmap =
  for n <- 0..65535 do
    r = div(n, 256)
    g = rem(n, 256)
    b = 255 - max(r, g)
    {r, g, b}
  end

Generate PNG image

pngex =
  Pngex.new()
  |> Pngex.set_type(:rgb)
  |> Pngex.set_depth(:depth8)
  |> Pngex.set_size(256, 256)

image = Pngex.generate(pngex, bitmap)

File.write("rgb8_256x256.png", image)

or

image =
  Pngex.new(
    type: :rgb,
    depth: :depth8,
    width: 256,
    height: 256
  )
  |> Pngex.generate(bitmap)

File.write("rgb8_256x256.png", image)

Indexed (Palette)

Prepare palette colors

palette = for n <- 0..255, do: {n, 255, 255 - n}

Prepare bitmap image data

bitmap = for n <- 0..65535, do: rem(n, 256)

Generate PNG image

image =
  Pngex.new(
    type: :indexed,
    depth: :depth8,
    width: 256,
    height: 256,
    palette: palette
  )
  |> Pngex.generate(bitmap)

File.write("indexed8_256x256.png", image)

Grayscale

Prepare bitmap image data

bitmap = for n <- 0..65535, do: rem(n, 256)

Generate PNG image

image =
  Pngex.new(
    type: :gray,
    depth: :depth8,
    width: 256,
    height: 256
  )
  |> Pngex.generate(bitmap)

File.write("gray8_256x256.png", image)

Avaiable formats