Imago, Elixir + Rust image perceptual hashing

Imago is a set of bindings (for my usage) to image-rs/image. Mainly because I didn’t find any Elixir/Erlang library to iterate over pixels of compressed formats like Jpeg. I’ll need to at least open/process a bit/save images from rust.

Its features are :

• getting a (w: u8, h: u8, pixels: Vec<u8>) of r/g/b/a, rgb, or rgba pixels
• getting a Vec<u8> that represents a luminance fingerprint.
• filters: threshold(path, threshold), dither_bayer(path, threshold)
• saving something as a PGM image (mainly to check validity.)

iex> Imago.read_pixels("/path/to/image.jpg|png|gif|ico|bmp|tiff") # Image formats are those of image-rs/image
{:ok,
 {1200, 1500, [131, 140, 157, 255, 130, 139, 156, 255, 131, 138, 156, 255, 131, 138, 156,
  255, 134, 139, 158, 255, 134, 139, 158, 255, 136, 139, 158, 255, 135, 138,
  157, 255, 135, 136, 156, 255, 135, 136, 156, 255, 136, 137, 157, 255, 136,
  137, 157, 255, ...]}}

iex(1)> Imago.get_fingerprint_4x4("/path/to/image.jpg")
{:ok,
 [132, 138, 103, 110, 138, 119, 112, 125, 127, 121, 120, 133, 134, 125, 131,
  139]}
  
iex(1)> Imago.get_fingerprint_8x8("/path/to/image.jpg")
{:ok,
 [113, 144, 157, 115, 100, 102, 106, 109, 130, 141, 169, 112, 103, 107, 113,
  114, 142, 143, 138, 108, 108, 112, 120, 123, 128, 139, 120, 112, 112, 115,
  129, 126, 130, 126, 124, 117, 116, 120, 130, 133, 132, 122, 123, 119, 120,
  124, 129, 137, ...]}

iex> Imago.read_pixels("/this/one/does/not/exist")
:error

iex> Imago.read_pixels("/this/one/is_a_text_file.txt")
:error

The luminance fingerprint is explain in the schematic below :

Imago was my first Elixir + Rust project as there weren’t many examples of uses of Rustler at the time. Today, information is more accessible. Its source is still available for reference here :

https://github.com/Lucassifoni/imago

Here are samples of pictures of skies (collected every minute for a few years with A+B designers), overlaid with their luminance maps :