Horizontal Image Concatenation

horizontal_image_concat.exs

System.put_env("EVISION_PREFER_PRECOMPILED", "true") # Remove if you use a platform on which Evision does not provide a pre-compiled library.

System.put_env("EVISION_PRECOMPILED_CACHE_DIR", "#{System.user_home!()}/.cache")

Mix.install(
  [
    {:nx, "~> 0.3"},
    {:exla, "~> 0.3"},
    {:evision, "~> 0.1.2", github: "cocoa-xu/evision", tag: "v0.1.2"}
  ],
  config: [
    nx: [default_backend: EXLA.Backend]
  ]
)

src_file = "ZACKY-3000.jpg"
src_file_ext = Path.extname(src_file)
src_file_basename = Path.basename(src_file, src_file_ext)

dst_file = "ZACKY-3000_d.jpg"

# image will be trimmed by shape after concatenation
shape = {3000, 3000, 3} # {image_height, image_width, num_channel}

# src_files is generated by Stream with counting up
src_files =
  Stream.unfold(0, fn counter -> {counter, counter + 1} end)
  |> Stream.map(& "#{src_file_basename}_#{&1}#{src_file_ext}")
  |> Stream.take_while(& File.exists?(&1))

src_files
|> Enum.map(& Evision.imread!(&1))
|> Enum.map(& Evision.Nx.to_nx(&1))
|> Nx.concatenate() # here is the most important
|> Nx.slice([0, 0, 0], Tuple.to_list(shape)) # here is the trimming code.
|> then(& Evision.Nx.to_mat!(&1))
|> then(& Evision.imwrite!(dst_file, &1))