Horizontal image division

horizontal_image_division.exs

# Setting for Evision to use precompiled version

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")

# Setting integration of Nx, EXLA and Evision

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]
  ]
)

# you can replace src_file to any image file.
src_file = "ZACKY-3000.jpg"

# div_size is the width to divide the image.
div_size = 256

dst_file_ext = Path.extname(src_file)
dst_file_basename = Path.basename(src_file, dst_file_ext)

# dst_files is generated by Stream with counting up
dst_files =
  Stream.unfold(0, fn counter -> {counter, counter + 1} end)
  |> Stream.map(& "#{dst_file_basename}_#{&1}#{dst_file_ext}")

div_img =
  Evision.imread!(src_file)
  |> Evision.Nx.to_nx()
  |> Nx.to_batched_list(div_size) # here is the most important of this program.
  |> Enum.map(& Evision.Nx.to_mat!(&1))

# generate dst_files to images
Enum.zip(div_img, dst_files)
|> Enum.map(fn {img, dst_file} -> Evision.imwrite!(dst_file, img) end)

Evision.Nx.to_nx() ->Evision.Mat.to_nx()
Evision.Nx.to_mat!(&1) ->Evision.Mat.from_nx(&1)

If an error occurs while writing the image, try using ImageWriter instead.

defmodule ImageWriter do
def write_image(img, dst_file) do
try do
Evision.imwrite(dst_file, img)
IO.puts("The image was successfully written to #{dst_file}")
rescue
_ ->
IO.puts("An error occurred while writing the image")
end
end
end