glexif

A pure Gleam library for parsing out EXIF data from JPEG files.

Supported Tags

See the below code snippet example for the currently supported tags that are parsed out. More will be coming as I work through examples.

Limitations

Limited parsing formats

I definitely am not an expert in photography, so I have left some of the values in their raw form so that I can convert them to something more useful in the future (see the TODO comments in glexif_test.gleam). If you have any input on what would be useful for a consumer of the library, feel free to put in an issue!

gleam add glexif

import glexif

pub fn main() {

  glexif.get_exif_data_for_file("test/fixtures/test.jpeg")
  |> should.equal(exif_tag.ExifTagRecord(
    make: Some("Apple"),
    model: Some("iPhone 14 Pro"),
    orientation: Some(orientation.Rotate90CW),
    x_resolution: Some(72),
    y_resolution: Some(72),
    resolution_unit: Some(resolution_unit.Inches),
    software: Some("17.2.1"),
    modify_date: Some("2024:02:18 17:34:57"),
    host_computer: Some("iPhone 14 Pro"),
    y_cb_cr_positioning: Some(y_cb_cr_positioning.Centered),
    exposure_time: Some(Fraction(1, 179)),
    f_number: Some(Fraction(89, 50)),
    exposure_program: Some(exposure_program.ProgramAE),
    iso: Some(64),
    exif_version: Some("0232"),
    date_time_original: Some("2024:02:18 17:34:57"),
    create_date: Some("2024:02:18 17:34:57"),
    offset_time: Some("-06:00"),
    offset_time_original: Some("-06:00"),
    offset_time_digitized: Some("-06:00"),
    components_configuration: Some([
      components_configuration.Y,
      components_configuration.Cb,
      components_configuration.Cr,
      components_configuration.NA,
    ]),
    // TODO: convert this to seconds instead of the raw fraction
    shutter_speed_value: Some(Fraction(124_929, 16_690)),
    // TODO: convert this to the human readable value that it should be
    aperature_value: Some(Fraction(163_775, 98_437)),
    brightness_value: Some(5.389648033126294),
    exposure_compensation: Some(Fraction(0, 1)),
    metering_mode: Some(metering_mode.MultiSegement),
    flash: Some(OffDidNotFire),
    // TODO: Need units? Or is it always millimeters? ExifTool rounds to 1 decimal, should I do that too?
    focal_length: Some(6.86),
    subject_area: Some([2009, 1505, 2208, 1324]),
    // TODO: parse out maker data. This is a whole ball of wax and I'm kicking the can down the road
    maker_data: Some(exif_tag.TBD),
    sub_sec_time_original: Some("289"),
    sub_sec_time_digitized: Some("289"),
    flash_pix_version: Some("0100"),
    color_space: Some(color_space.Uncalibrated),
    exif_image_width: Some(4032),
    exif_image_height: Some(3024),
    sensing_method: Some(sensing_method.OneChipColorArea),
    scene_type: Some(scene_type.DirectlyPhotographed),
    exposure_mode: Some(exposure_mode.Auto),
    white_balance: Some(white_balance.Auto),
    focal_length_in_35_mm_format: Some(24),
    scene_capture_type: Some(scene_capture_type.Standard),
    //TODO: Convert these 4 rational numbers to something useful
    lens_info: Some([
      Fraction(1_551_800, 699_009),
      Fraction(9, 1),
      Fraction(1_244_236, 699_009),
      Fraction(14, 5),
    ]),
    lens_make: Some("Apple"),
    lens_model: Some("iPhone 14 Pro back triple camera 6.86mm f/1.78"),
    composite_image: Some(composite_image.GeneralCompositeImage),
    gps_latitude_ref: Some("N"),
    gps_latitude: Some(gps_coordinates.GPSCoordinates(44, 58, 29.31)),
    gps_longitude_ref: Some("W"),
    gps_longitude: Some(gps_coordinates.GPSCoordinates(93, 15, 35.93)),
    gps_altitude_ref: Some(gps_altitude_ref.AboveSeaLevel),
    gps_altitude: Some(245.97845468053492),
  ))
}

Further documentation can be found at https://hexdocs.pm/glexif.

Development

gleam test  # Run the tests