Flexo

For when you want to see if two images aren't quite the same.

Interface

Flexo.compare(
  image_a_path : String,
  image_b_path : String,
  threshold : Float32 = 0.0) : Result

Compares two images of the same size at the given file paths with an optional threshold for if they are considered a match. Returns a Result

Result#score

The ratio of pixels that are different between the two images and the total number of pixels of one of those images.

Result#match?

A boolean value that represents whether the two compared images are a match given the threshold provided when comparing them.

Result#save(path : String)

Saves the diff image between the two images to the given path. Differences appear as the colour StumpyCore::RGBA::LIME overlaid on the first image.

Usage

Install the flexo shard

1. shards init

2. Add the dependency to shards.yml

   ...
   dependencies:
   flexo:
     github: pschulze/flexo
     version: "~> 0.1"
   ...

3. shards install

Comparing Images

require "flexo"

result = Flexo.compare("path/to/first/image.png", "path/to/second/image.png")
puts result.score
puts result.match?
result.save("output/path/of/diff/image.png")

Examples

1. Install Crystal

2. Run:

   git clone git@github.com:pschulze/flexo.git
   cd flexo
   shards install
   crystal examples/corgi_comparison.cr