README.md

Pexelmatch

Pexelmatch is a pure Elixir port of Pixelmatch. We used the same fixtures and tests as Pixelmatch, opting for consistency over correctness. The library is a bit slower, and and doesn't currently offer a binary, but otherwise is feature complete.

We used the same semantics for calling the module. We have not released a binary for it yet. If you'd like to compare images from the command line, just use the Pixelmatch binary.

Installation

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

def deps do
  [
    {:pexelmatch, "~> 0.0.1"}
  ]
end

Usage

You can call the top-level API with &Pexelmatch.run\4 or &Pexelmatch.run\5 (with opts). Pass it image paths, and it will handle the file IO, and compare the images. It will return {:ok, number_of_pixels_changed} and write the diff to the diff path.

  Pexelmatch.run("/path/image.png" "/path/image_2.png"), "./path/diff.png", opts)
  > {:ok, 1}

You can also call &Pexelmatch.Match.apply\3. If will not perform any file I/O, and will return {:ok, number_of_pixels_changed, diff_data}. You are responsible for writing the diff data to disk. In this example we use ExPng for file I/O.

  alias ExPng.Image

  {:ok, img_1} = Image.from_file("/path/img_1.png")
  {:ok, img_2} = Image.from_file("/path/img_2.png")
  {:ok, num_pixels, diff_data} = Match.apply(img_1, img_2, options)
  Image.to_file(diff_data, Path.join(".", "/test/fixtures/temp_diff.png"))

Options work the same way as pixelmatch, but are snake cased.