My working unpac space for OCaml projects in development
Extract EXIF module to separate ocaml-exif library
- Remove local exif.ml and exif.mli (now in ocaml-exif package)
- Add ocaml-exif dependency to dune-project and src/dune
- All 21 tests still pass
The EXIF parsing functionality is now available as a reusable
opam library with comprehensive documentation.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
+4
-1256
+2
-1
dune-project
+2
-1
dune-project
+1
ocaml-jpeg.opam
+1
ocaml-jpeg.opam
+1
src/dune
+1
src/dune
-884
src/exif.ml
-884
src/exif.ml
···
1
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(** Pure OCaml EXIF parsing library
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Based on EXIF 2.32 specification and libexif reference implementation.
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EXIF data is stored in JPEG APP1 markers with the prefix "Exif\x00\x00".
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The data follows TIFF format with IFDs (Image File Directories). *)
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(** {1 Types} *)
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(** Byte order for multi-byte values *)
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type byte_order =
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| Big_endian (** "MM" - Motorola byte order *)
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| Little_endian (** "II" - Intel byte order *)
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-
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(** EXIF data formats (TIFF types) *)
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type format =
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| Byte (** 8-bit unsigned integer *)
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| Ascii (** 8-bit byte containing 7-bit ASCII *)
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| Short (** 16-bit unsigned integer *)
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| Long (** 32-bit unsigned integer *)
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| Rational (** Two LONGs: numerator and denominator *)
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| Sbyte (** 8-bit signed integer *)
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| Undefined (** 8-bit byte *)
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| Sshort (** 16-bit signed integer *)
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| Slong (** 32-bit signed integer *)
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| Srational (** Two SLONGs: numerator and denominator *)
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| Float (** Single precision IEEE float *)
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| Double (** Double precision IEEE float *)
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(** Image File Directory types *)
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type ifd =
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| IFD0 (** Primary image IFD *)
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| IFD1 (** Thumbnail image IFD *)
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| EXIF (** EXIF private tags IFD *)
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| GPS (** GPS info IFD *)
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| Interoperability (** Interoperability IFD *)
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(** Rational number (numerator/denominator) *)
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type rational = {
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numerator : int32;
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denominator : int32;
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}
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(** Signed rational number *)
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type srational = {
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snumerator : int32;
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sdenominator : int32;
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}
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(** EXIF tag values *)
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type value =
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| VByte of int array
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| VAscii of string
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| VShort of int array
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| VLong of int32 array
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| VRational of rational array
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| VSbyte of int array
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| VUndefined of bytes
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| VSshort of int array
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| VSlong of int32 array
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| VSrational of srational array
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| VFloat of float array
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| VDouble of float array
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(** A single EXIF entry *)
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type entry = {
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tag : int;
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ifd : ifd;
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format : format;
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components : int;
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value : value;
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}
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(** Complete EXIF data *)
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type t = {
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byte_order : byte_order;
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entries : entry list;
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thumbnail : bytes option;
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}
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(** {1 Tag constants} *)
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(** Common EXIF tags *)
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module Tag = struct
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(* IFD0/IFD1 tags *)
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let image_width = 0x0100
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let image_length = 0x0101
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let bits_per_sample = 0x0102
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let compression = 0x0103
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let photometric_interpretation = 0x0106
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let image_description = 0x010e
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let make = 0x010f
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let model = 0x0110
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let strip_offsets = 0x0111
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let orientation = 0x0112
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let samples_per_pixel = 0x0115
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let rows_per_strip = 0x0116
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let strip_byte_counts = 0x0117
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let x_resolution = 0x011a
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let y_resolution = 0x011b
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let planar_configuration = 0x011c
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let resolution_unit = 0x0128
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let transfer_function = 0x012d
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let software = 0x0131
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let date_time = 0x0132
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let artist = 0x013b
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let white_point = 0x013e
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let primary_chromaticities = 0x013f
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let jpeg_interchange_format = 0x0201
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let jpeg_interchange_format_length = 0x0202
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let ycbcr_coefficients = 0x0211
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let ycbcr_sub_sampling = 0x0212
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let ycbcr_positioning = 0x0213
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let reference_black_white = 0x0214
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let copyright = 0x8298
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let exif_ifd_pointer = 0x8769
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let gps_info_ifd_pointer = 0x8825
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(* EXIF IFD tags *)
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let exposure_time = 0x829a
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let f_number = 0x829d
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let exposure_program = 0x8822
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let spectral_sensitivity = 0x8824
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let iso_speed_ratings = 0x8827
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let oecf = 0x8828
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let sensitivity_type = 0x8830
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let exif_version = 0x9000
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let date_time_original = 0x9003
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let date_time_digitized = 0x9004
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let offset_time = 0x9010
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let offset_time_original = 0x9011
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let offset_time_digitized = 0x9012
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let components_configuration = 0x9101
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let compressed_bits_per_pixel = 0x9102
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let shutter_speed_value = 0x9201
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let aperture_value = 0x9202
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let brightness_value = 0x9203
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let exposure_bias_value = 0x9204
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let max_aperture_value = 0x9205
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let subject_distance = 0x9206
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let metering_mode = 0x9207
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let light_source = 0x9208
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let flash = 0x9209
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let focal_length = 0x920a
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let subject_area = 0x9214
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let maker_note = 0x927c
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let user_comment = 0x9286
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let sub_sec_time = 0x9290
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let sub_sec_time_original = 0x9291
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let sub_sec_time_digitized = 0x9292
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let flash_pix_version = 0xa000
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let color_space = 0xa001
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let pixel_x_dimension = 0xa002
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let pixel_y_dimension = 0xa003
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let related_sound_file = 0xa004
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let interoperability_ifd_pointer = 0xa005
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let flash_energy = 0xa20b
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let spatial_frequency_response = 0xa20c
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let focal_plane_x_resolution = 0xa20e
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let focal_plane_y_resolution = 0xa20f
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let focal_plane_resolution_unit = 0xa210
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let subject_location = 0xa214
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let exposure_index = 0xa215
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let sensing_method = 0xa217
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let file_source = 0xa300
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let scene_type = 0xa301
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let cfa_pattern = 0xa302
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let custom_rendered = 0xa401
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let exposure_mode = 0xa402
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let white_balance = 0xa403
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let digital_zoom_ratio = 0xa404
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let focal_length_in_35mm_film = 0xa405
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let scene_capture_type = 0xa406
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let gain_control = 0xa407
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let contrast = 0xa408
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let saturation = 0xa409
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let sharpness = 0xa40a
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let device_setting_description = 0xa40b
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let subject_distance_range = 0xa40c
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let image_unique_id = 0xa420
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let camera_owner_name = 0xa430
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let body_serial_number = 0xa431
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let lens_specification = 0xa432
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let lens_make = 0xa433
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let lens_model = 0xa434
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let lens_serial_number = 0xa435
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let gamma = 0xa500
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(* GPS tags *)
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let gps_version_id = 0x0000
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let gps_latitude_ref = 0x0001
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let gps_latitude = 0x0002
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let gps_longitude_ref = 0x0003
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let gps_longitude = 0x0004
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let gps_altitude_ref = 0x0005
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let gps_altitude = 0x0006
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let gps_time_stamp = 0x0007
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let gps_satellites = 0x0008
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let gps_status = 0x0009
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let gps_measure_mode = 0x000a
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let gps_dop = 0x000b
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let gps_speed_ref = 0x000c
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let gps_speed = 0x000d
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let gps_track_ref = 0x000e
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let gps_track = 0x000f
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let gps_img_direction_ref = 0x0010
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let gps_img_direction = 0x0011
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let gps_map_datum = 0x0012
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let gps_dest_latitude_ref = 0x0013
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let gps_dest_latitude = 0x0014
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let gps_dest_longitude_ref = 0x0015
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let gps_dest_longitude = 0x0016
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let gps_dest_bearing_ref = 0x0017
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let gps_dest_bearing = 0x0018
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let gps_dest_distance_ref = 0x0019
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let gps_dest_distance = 0x001a
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let gps_processing_method = 0x001b
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let gps_area_information = 0x001c
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let gps_date_stamp = 0x001d
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let gps_differential = 0x001e
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let gps_h_positioning_error = 0x001f
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(** Get human-readable name for a tag *)
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let name_of_tag tag ifd =
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match ifd with
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| GPS -> (
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match tag with
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| 0x0000 -> "GPSVersionID"
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| 0x0001 -> "GPSLatitudeRef"
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| 0x0002 -> "GPSLatitude"
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| 0x0003 -> "GPSLongitudeRef"
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| 0x0004 -> "GPSLongitude"
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| 0x0005 -> "GPSAltitudeRef"
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| 0x0006 -> "GPSAltitude"
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| 0x0007 -> "GPSTimeStamp"
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| 0x0008 -> "GPSSatellites"
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| 0x0009 -> "GPSStatus"
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| 0x000a -> "GPSMeasureMode"
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| 0x000b -> "GPSDOP"
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| 0x000c -> "GPSSpeedRef"
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| 0x000d -> "GPSSpeed"
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| 0x000e -> "GPSTrackRef"
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| 0x000f -> "GPSTrack"
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| 0x0010 -> "GPSImgDirectionRef"
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| 0x0011 -> "GPSImgDirection"
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| 0x0012 -> "GPSMapDatum"
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| 0x001d -> "GPSDateStamp"
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| _ -> Printf.sprintf "GPS_0x%04x" tag)
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| _ -> (
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match tag with
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| 0x0100 -> "ImageWidth"
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| 0x0101 -> "ImageLength"
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| 0x0102 -> "BitsPerSample"
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| 0x0103 -> "Compression"
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| 0x0106 -> "PhotometricInterpretation"
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| 0x010e -> "ImageDescription"
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| 0x010f -> "Make"
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| 0x0110 -> "Model"
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| 0x0111 -> "StripOffsets"
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| 0x0112 -> "Orientation"
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| 0x0115 -> "SamplesPerPixel"
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| 0x0116 -> "RowsPerStrip"
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| 0x0117 -> "StripByteCounts"
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| 0x011a -> "XResolution"
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| 0x011b -> "YResolution"
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| 0x011c -> "PlanarConfiguration"
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| 0x0128 -> "ResolutionUnit"
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| 0x012d -> "TransferFunction"
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| 0x0131 -> "Software"
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| 0x0132 -> "DateTime"
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| 0x013b -> "Artist"
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| 0x013e -> "WhitePoint"
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| 0x013f -> "PrimaryChromaticities"
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| 0x0201 -> "JPEGInterchangeFormat"
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| 0x0202 -> "JPEGInterchangeFormatLength"
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| 0x0211 -> "YCbCrCoefficients"
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| 0x0212 -> "YCbCrSubSampling"
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| 0x0213 -> "YCbCrPositioning"
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| 0x0214 -> "ReferenceBlackWhite"
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| 0x8298 -> "Copyright"
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| 0x8769 -> "ExifIFDPointer"
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| 0x8825 -> "GPSInfoIFDPointer"
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| 0x829a -> "ExposureTime"
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| 0x829d -> "FNumber"
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| 0x8822 -> "ExposureProgram"
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| 0x8824 -> "SpectralSensitivity"
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| 0x8827 -> "ISOSpeedRatings"
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| 0x9000 -> "ExifVersion"
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| 0x9003 -> "DateTimeOriginal"
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| 0x9004 -> "DateTimeDigitized"
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| 0x9010 -> "OffsetTime"
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| 0x9011 -> "OffsetTimeOriginal"
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| 0x9012 -> "OffsetTimeDigitized"
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| 0x9101 -> "ComponentsConfiguration"
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| 0x9102 -> "CompressedBitsPerPixel"
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| 0x9201 -> "ShutterSpeedValue"
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| 0x9202 -> "ApertureValue"
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| 0x9203 -> "BrightnessValue"
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| 0x9204 -> "ExposureBiasValue"
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| 0x9205 -> "MaxApertureValue"
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| 0x9206 -> "SubjectDistance"
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| 0x9207 -> "MeteringMode"
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| 0x9208 -> "LightSource"
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| 0x9209 -> "Flash"
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| 0x920a -> "FocalLength"
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| 0x9214 -> "SubjectArea"
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| 0x927c -> "MakerNote"
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| 0x9286 -> "UserComment"
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| 0x9290 -> "SubSecTime"
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| 0x9291 -> "SubSecTimeOriginal"
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| 0x9292 -> "SubSecTimeDigitized"
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| 0xa000 -> "FlashPixVersion"
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| 0xa001 -> "ColorSpace"
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| 0xa002 -> "PixelXDimension"
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| 0xa003 -> "PixelYDimension"
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| 0xa004 -> "RelatedSoundFile"
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| 0xa005 -> "InteroperabilityIFDPointer"
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| 0xa20b -> "FlashEnergy"
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| 0xa20c -> "SpatialFrequencyResponse"
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| 0xa20e -> "FocalPlaneXResolution"
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| 0xa20f -> "FocalPlaneYResolution"
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| 0xa210 -> "FocalPlaneResolutionUnit"
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| 0xa214 -> "SubjectLocation"
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| 0xa215 -> "ExposureIndex"
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| 0xa217 -> "SensingMethod"
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| 0xa300 -> "FileSource"
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| 0xa301 -> "SceneType"
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| 0xa302 -> "CFAPattern"
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| 0xa401 -> "CustomRendered"
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| 0xa402 -> "ExposureMode"
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| 0xa403 -> "WhiteBalance"
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| 0xa404 -> "DigitalZoomRatio"
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| 0xa405 -> "FocalLengthIn35mmFilm"
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| 0xa406 -> "SceneCaptureType"
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| 0xa407 -> "GainControl"
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| 0xa408 -> "Contrast"
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| 0xa409 -> "Saturation"
338
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| 0xa40a -> "Sharpness"
339
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| 0xa40c -> "SubjectDistanceRange"
340
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| 0xa420 -> "ImageUniqueID"
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| 0xa430 -> "CameraOwnerName"
342
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| 0xa431 -> "BodySerialNumber"
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| 0xa432 -> "LensSpecification"
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| 0xa433 -> "LensMake"
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| 0xa434 -> "LensModel"
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| 0xa435 -> "LensSerialNumber"
347
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| 0xa500 -> "Gamma"
348
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| _ -> Printf.sprintf "Tag_0x%04x" tag)
349
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end
350
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351
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(** {1 Parsing} *)
352
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353
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(** Parse error *)
354
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exception Parse_error of string
355
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356
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(** Size in bytes for each format type *)
357
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let format_size = function
358
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| Byte | Ascii | Sbyte | Undefined -> 1
359
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| Short | Sshort -> 2
360
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| Long | Slong | Float -> 4
361
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| Rational | Srational | Double -> 8
362
-
363
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(** Convert format code to format type *)
364
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let format_of_int = function
365
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| 1 -> Byte
366
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| 2 -> Ascii
367
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| 3 -> Short
368
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| 4 -> Long
369
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| 5 -> Rational
370
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| 6 -> Sbyte
371
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| 7 -> Undefined
372
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| 8 -> Sshort
373
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| 9 -> Slong
374
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| 10 -> Srational
375
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| 11 -> Float
376
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| 12 -> Double
377
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| n -> raise (Parse_error (Printf.sprintf "Unknown format: %d" n))
378
-
379
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(** Read 16-bit value with given byte order *)
380
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let read_u16 data offset byte_order =
381
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let b0 = Bytes.get_uint8 data offset in
382
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let b1 = Bytes.get_uint8 data (offset + 1) in
383
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match byte_order with
384
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| Big_endian -> (b0 lsl 8) lor b1
385
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| Little_endian -> (b1 lsl 8) lor b0
386
-
387
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(** Read 32-bit value with given byte order *)
388
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let read_u32 data offset byte_order =
389
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let b0 = Int32.of_int (Bytes.get_uint8 data offset) in
390
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let b1 = Int32.of_int (Bytes.get_uint8 data (offset + 1)) in
391
-
let b2 = Int32.of_int (Bytes.get_uint8 data (offset + 2)) in
392
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let b3 = Int32.of_int (Bytes.get_uint8 data (offset + 3)) in
393
-
match byte_order with
394
-
| Big_endian ->
395
-
Int32.(logor (shift_left b0 24)
396
-
(logor (shift_left b1 16)
397
-
(logor (shift_left b2 8) b3)))
398
-
| Little_endian ->
399
-
Int32.(logor (shift_left b3 24)
400
-
(logor (shift_left b2 16)
401
-
(logor (shift_left b1 8) b0)))
402
-
403
-
(** Read signed 32-bit value *)
404
-
let read_s32 data offset byte_order =
405
-
read_u32 data offset byte_order
406
-
407
-
(** Read a float (IEEE 754 single) *)
408
-
let read_float data offset byte_order =
409
-
Int32.float_of_bits (read_u32 data offset byte_order)
410
-
411
-
(** Read a double (IEEE 754 double) *)
412
-
let read_double data offset byte_order =
413
-
let b = Bytes.create 8 in
414
-
(match byte_order with
415
-
| Big_endian ->
416
-
for i = 0 to 7 do
417
-
Bytes.set b i (Bytes.get data (offset + i))
418
-
done
419
-
| Little_endian ->
420
-
for i = 0 to 7 do
421
-
Bytes.set b (7 - i) (Bytes.get data (offset + i))
422
-
done);
423
-
Int64.float_of_bits (Bytes.get_int64_be b 0)
424
-
425
-
(** Parse entry value from data *)
426
-
let parse_value data offset byte_order format components =
427
-
let size = format_size format * components in
428
-
if offset + size > Bytes.length data then
429
-
raise (Parse_error "Value extends beyond data");
430
-
match format with
431
-
| Byte ->
432
-
VByte (Array.init components (fun i ->
433
-
Bytes.get_uint8 data (offset + i)))
434
-
| Ascii ->
435
-
(* Strip trailing NUL *)
436
-
let s = Bytes.sub_string data offset components in
437
-
let len = String.length s in
438
-
let s = if len > 0 && s.[len - 1] = '\000' then
439
-
String.sub s 0 (len - 1)
440
-
else s in
441
-
VAscii s
442
-
| Short ->
443
-
VShort (Array.init components (fun i ->
444
-
read_u16 data (offset + i * 2) byte_order))
445
-
| Long ->
446
-
VLong (Array.init components (fun i ->
447
-
read_u32 data (offset + i * 4) byte_order))
448
-
| Rational ->
449
-
VRational (Array.init components (fun i ->
450
-
let off = offset + i * 8 in
451
-
{ numerator = read_u32 data off byte_order;
452
-
denominator = read_u32 data (off + 4) byte_order }))
453
-
| Sbyte ->
454
-
VSbyte (Array.init components (fun i ->
455
-
let v = Bytes.get_uint8 data (offset + i) in
456
-
if v >= 128 then v - 256 else v))
457
-
| Undefined ->
458
-
VUndefined (Bytes.sub data offset components)
459
-
| Sshort ->
460
-
VSshort (Array.init components (fun i ->
461
-
let v = read_u16 data (offset + i * 2) byte_order in
462
-
if v >= 32768 then v - 65536 else v))
463
-
| Slong ->
464
-
VSlong (Array.init components (fun i ->
465
-
read_s32 data (offset + i * 4) byte_order))
466
-
| Srational ->
467
-
VSrational (Array.init components (fun i ->
468
-
let off = offset + i * 8 in
469
-
{ snumerator = read_s32 data off byte_order;
470
-
sdenominator = read_s32 data (off + 4) byte_order }))
471
-
| Float ->
472
-
VFloat (Array.init components (fun i ->
473
-
read_float data (offset + i * 4) byte_order))
474
-
| Double ->
475
-
VDouble (Array.init components (fun i ->
476
-
read_double data (offset + i * 8) byte_order))
477
-
478
-
(** Parse a single IFD entry *)
479
-
let parse_entry data offset byte_order ifd =
480
-
if offset + 12 > Bytes.length data then
481
-
raise (Parse_error "Entry extends beyond data");
482
-
483
-
let tag = read_u16 data offset byte_order in
484
-
let format_code = read_u16 data (offset + 2) byte_order in
485
-
let format = format_of_int format_code in
486
-
let components = Int32.to_int (read_u32 data (offset + 4) byte_order) in
487
-
let value_size = format_size format * components in
488
-
489
-
(* Value is inline if <= 4 bytes, otherwise it's an offset *)
490
-
let value_offset =
491
-
if value_size <= 4 then
492
-
offset + 8
493
-
else
494
-
Int32.to_int (read_u32 data (offset + 8) byte_order)
495
-
in
496
-
497
-
let value = parse_value data value_offset byte_order format components in
498
-
{ tag; ifd; format; components; value }
499
-
500
-
(** Parse an IFD and return entries and next IFD offset *)
501
-
let parse_ifd data offset byte_order ifd =
502
-
if offset + 2 > Bytes.length data then
503
-
raise (Parse_error "IFD extends beyond data");
504
-
505
-
let entry_count = read_u16 data offset byte_order in
506
-
let entries_end = offset + 2 + entry_count * 12 in
507
-
508
-
if entries_end + 4 > Bytes.length data then
509
-
raise (Parse_error "IFD entries extend beyond data");
510
-
511
-
let entries = List.init entry_count (fun i ->
512
-
parse_entry data (offset + 2 + i * 12) byte_order ifd)
513
-
in
514
-
515
-
let next_ifd_offset = Int32.to_int (read_u32 data entries_end byte_order) in
516
-
(entries, next_ifd_offset)
517
-
518
-
(** Parse complete EXIF data from bytes *)
519
-
let parse data =
520
-
let len = Bytes.length data in
521
-
if len < 8 then
522
-
raise (Parse_error "Data too short for EXIF header");
523
-
524
-
(* Check byte order marker *)
525
-
let byte_order =
526
-
match Bytes.get_uint8 data 0, Bytes.get_uint8 data 1 with
527
-
| 0x4D, 0x4D -> Big_endian (* "MM" *)
528
-
| 0x49, 0x49 -> Little_endian (* "II" *)
529
-
| _ -> raise (Parse_error "Invalid byte order marker")
530
-
in
531
-
532
-
(* Check TIFF magic number *)
533
-
let magic = read_u16 data 2 byte_order in
534
-
if magic <> 42 then
535
-
raise (Parse_error (Printf.sprintf "Invalid TIFF magic: %d" magic));
536
-
537
-
(* Get offset to first IFD *)
538
-
let ifd0_offset = Int32.to_int (read_u32 data 4 byte_order) in
539
-
if ifd0_offset < 8 || ifd0_offset >= len then
540
-
raise (Parse_error "Invalid IFD0 offset");
541
-
542
-
(* Parse IFD0 *)
543
-
let ifd0_entries, ifd1_offset = parse_ifd data ifd0_offset byte_order IFD0 in
544
-
545
-
(* Look for EXIF IFD pointer *)
546
-
let exif_entries =
547
-
match List.find_opt (fun e -> e.tag = Tag.exif_ifd_pointer) ifd0_entries with
548
-
| Some { value = VLong [| offset |]; _ } ->
549
-
let off = Int32.to_int offset in
550
-
if off > 0 && off < len then
551
-
let entries, _ = parse_ifd data off byte_order EXIF in
552
-
entries
553
-
else []
554
-
| _ -> []
555
-
in
556
-
557
-
(* Look for GPS IFD pointer *)
558
-
let gps_entries =
559
-
match List.find_opt (fun e -> e.tag = Tag.gps_info_ifd_pointer) ifd0_entries with
560
-
| Some { value = VLong [| offset |]; _ } ->
561
-
let off = Int32.to_int offset in
562
-
if off > 0 && off < len then
563
-
let entries, _ = parse_ifd data off byte_order GPS in
564
-
entries
565
-
else []
566
-
| _ -> []
567
-
in
568
-
569
-
(* Look for Interoperability IFD pointer in EXIF IFD *)
570
-
let interop_entries =
571
-
match List.find_opt (fun e -> e.tag = Tag.interoperability_ifd_pointer) exif_entries with
572
-
| Some { value = VLong [| offset |]; _ } ->
573
-
let off = Int32.to_int offset in
574
-
if off > 0 && off < len then
575
-
let entries, _ = parse_ifd data off byte_order Interoperability in
576
-
entries
577
-
else []
578
-
| _ -> []
579
-
in
580
-
581
-
(* Parse IFD1 (thumbnail) if present *)
582
-
let ifd1_entries, thumbnail =
583
-
if ifd1_offset > 0 && ifd1_offset < len then
584
-
let entries, _ = parse_ifd data ifd1_offset byte_order IFD1 in
585
-
(* Look for JPEG thumbnail *)
586
-
let thumb_offset =
587
-
match List.find_opt (fun e -> e.tag = Tag.jpeg_interchange_format) entries with
588
-
| Some { value = VLong [| off |]; _ } -> Some (Int32.to_int off)
589
-
| _ -> None
590
-
in
591
-
let thumb_length =
592
-
match List.find_opt (fun e -> e.tag = Tag.jpeg_interchange_format_length) entries with
593
-
| Some { value = VLong [| len |]; _ } -> Some (Int32.to_int len)
594
-
| _ -> None
595
-
in
596
-
let thumbnail =
597
-
match thumb_offset, thumb_length with
598
-
| Some off, Some len when off > 0 && off + len <= Bytes.length data ->
599
-
Some (Bytes.sub data off len)
600
-
| _ -> None
601
-
in
602
-
(entries, thumbnail)
603
-
else
604
-
([], None)
605
-
in
606
-
607
-
let entries =
608
-
ifd0_entries @ ifd1_entries @ exif_entries @ gps_entries @ interop_entries
609
-
in
610
-
611
-
{ byte_order; entries; thumbnail }
612
-
613
-
(** Parse EXIF data from a JPEG APP1 segment (with "Exif\x00\x00" prefix stripped) *)
614
-
let parse_from_app1 data =
615
-
parse data
616
-
617
-
(** {1 Query functions} *)
618
-
619
-
(** Find entry by tag in any IFD *)
620
-
let find_entry tag exif =
621
-
List.find_opt (fun e -> e.tag = tag) exif.entries
622
-
623
-
(** Find entry by tag in specific IFD *)
624
-
let find_entry_in_ifd tag ifd exif =
625
-
List.find_opt (fun e -> e.tag = tag && e.ifd = ifd) exif.entries
626
-
627
-
(** Get all entries for a specific IFD *)
628
-
let entries_in_ifd ifd exif =
629
-
List.filter (fun e -> e.ifd = ifd) exif.entries
630
-
631
-
(** {1 Value extraction helpers} *)
632
-
633
-
(** Get ASCII string value *)
634
-
let get_string entry =
635
-
match entry.value with
636
-
| VAscii s -> Some s
637
-
| _ -> None
638
-
639
-
(** Get single SHORT value *)
640
-
let get_short entry =
641
-
match entry.value with
642
-
| VShort [| v |] -> Some v
643
-
| _ -> None
644
-
645
-
(** Get single LONG value *)
646
-
let get_long entry =
647
-
match entry.value with
648
-
| VLong [| v |] -> Some (Int32.to_int v)
649
-
| _ -> None
650
-
651
-
(** Get single RATIONAL value as float *)
652
-
let get_rational entry =
653
-
match entry.value with
654
-
| VRational [| { numerator; denominator } |] ->
655
-
if denominator = 0l then None
656
-
else Some (Int32.to_float numerator /. Int32.to_float denominator)
657
-
| _ -> None
658
-
659
-
(** Get RATIONAL array as floats *)
660
-
let get_rationals entry =
661
-
match entry.value with
662
-
| VRational arr ->
663
-
Some (Array.map (fun { numerator; denominator } ->
664
-
if denominator = 0l then 0.0
665
-
else Int32.to_float numerator /. Int32.to_float denominator) arr)
666
-
| _ -> None
667
-
668
-
(** {1 Common metadata accessors} *)
669
-
670
-
(** Get camera make *)
671
-
let make exif =
672
-
Option.bind (find_entry Tag.make exif) get_string
673
-
674
-
(** Get camera model *)
675
-
let model exif =
676
-
Option.bind (find_entry Tag.model exif) get_string
677
-
678
-
(** Get software *)
679
-
let software exif =
680
-
Option.bind (find_entry Tag.software exif) get_string
681
-
682
-
(** Get image description *)
683
-
let image_description exif =
684
-
Option.bind (find_entry Tag.image_description exif) get_string
685
-
686
-
(** Get artist *)
687
-
let artist exif =
688
-
Option.bind (find_entry Tag.artist exif) get_string
689
-
690
-
(** Get copyright *)
691
-
let copyright exif =
692
-
Option.bind (find_entry Tag.copyright exif) get_string
693
-
694
-
(** Get date/time original *)
695
-
let date_time_original exif =
696
-
Option.bind (find_entry Tag.date_time_original exif) get_string
697
-
698
-
(** Get date/time digitized *)
699
-
let date_time_digitized exif =
700
-
Option.bind (find_entry Tag.date_time_digitized exif) get_string
701
-
702
-
(** Get date/time *)
703
-
let date_time exif =
704
-
Option.bind (find_entry Tag.date_time exif) get_string
705
-
706
-
(** Get orientation (1-8) *)
707
-
let orientation exif =
708
-
Option.bind (find_entry Tag.orientation exif) get_short
709
-
710
-
(** Get image width *)
711
-
let image_width exif =
712
-
match find_entry Tag.image_width exif with
713
-
| Some e -> (
714
-
match e.value with
715
-
| VShort [| v |] -> Some v
716
-
| VLong [| v |] -> Some (Int32.to_int v)
717
-
| _ -> None)
718
-
| None -> None
719
-
720
-
(** Get image height *)
721
-
let image_height exif =
722
-
match find_entry Tag.image_length exif with
723
-
| Some e -> (
724
-
match e.value with
725
-
| VShort [| v |] -> Some v
726
-
| VLong [| v |] -> Some (Int32.to_int v)
727
-
| _ -> None)
728
-
| None -> None
729
-
730
-
(** Get X resolution *)
731
-
let x_resolution exif =
732
-
Option.bind (find_entry Tag.x_resolution exif) get_rational
733
-
734
-
(** Get Y resolution *)
735
-
let y_resolution exif =
736
-
Option.bind (find_entry Tag.y_resolution exif) get_rational
737
-
738
-
(** Get resolution unit (1=none, 2=inch, 3=cm) *)
739
-
let resolution_unit exif =
740
-
Option.bind (find_entry Tag.resolution_unit exif) get_short
741
-
742
-
(** Get exposure time in seconds *)
743
-
let exposure_time exif =
744
-
Option.bind (find_entry Tag.exposure_time exif) get_rational
745
-
746
-
(** Get F-number *)
747
-
let f_number exif =
748
-
Option.bind (find_entry Tag.f_number exif) get_rational
749
-
750
-
(** Get ISO speed *)
751
-
let iso_speed exif =
752
-
match find_entry Tag.iso_speed_ratings exif with
753
-
| Some { value = VShort [| v |]; _ } -> Some v
754
-
| Some { value = VShort arr; _ } when Array.length arr > 0 -> Some arr.(0)
755
-
| _ -> None
756
-
757
-
(** Get focal length in mm *)
758
-
let focal_length exif =
759
-
Option.bind (find_entry Tag.focal_length exif) get_rational
760
-
761
-
(** Get focal length in 35mm equivalent *)
762
-
let focal_length_35mm exif =
763
-
Option.bind (find_entry Tag.focal_length_in_35mm_film exif) get_short
764
-
765
-
(** Get flash status *)
766
-
let flash exif =
767
-
Option.bind (find_entry Tag.flash exif) get_short
768
-
769
-
(** Get color space (1=sRGB, 65535=uncalibrated) *)
770
-
let color_space exif =
771
-
Option.bind (find_entry Tag.color_space exif) get_short
772
-
773
-
(** Get EXIF version string *)
774
-
let exif_version exif =
775
-
match find_entry Tag.exif_version exif with
776
-
| Some { value = VUndefined b; _ } -> Some (Bytes.to_string b)
777
-
| _ -> None
778
-
779
-
(** {1 GPS accessors} *)
780
-
781
-
(** Convert DMS (degrees/minutes/seconds) rationals to decimal degrees *)
782
-
let dms_to_decimal rationals =
783
-
if Array.length rationals < 3 then None
784
-
else
785
-
let degrees = Int32.to_float rationals.(0).numerator /.
786
-
Int32.to_float rationals.(0).denominator in
787
-
let minutes = Int32.to_float rationals.(1).numerator /.
788
-
Int32.to_float rationals.(1).denominator in
789
-
let seconds = Int32.to_float rationals.(2).numerator /.
790
-
Int32.to_float rationals.(2).denominator in
791
-
Some (degrees +. minutes /. 60.0 +. seconds /. 3600.0)
792
-
793
-
(** Get GPS latitude in decimal degrees (negative for South) *)
794
-
let gps_latitude exif =
795
-
match find_entry_in_ifd Tag.gps_latitude GPS exif with
796
-
| Some { value = VRational arr; _ } -> (
797
-
match dms_to_decimal arr with
798
-
| Some lat -> (
799
-
match find_entry_in_ifd Tag.gps_latitude_ref GPS exif with
800
-
| Some { value = VAscii "S"; _ } -> Some (-.lat)
801
-
| _ -> Some lat)
802
-
| None -> None)
803
-
| _ -> None
804
-
805
-
(** Get GPS longitude in decimal degrees (negative for West) *)
806
-
let gps_longitude exif =
807
-
match find_entry_in_ifd Tag.gps_longitude GPS exif with
808
-
| Some { value = VRational arr; _ } -> (
809
-
match dms_to_decimal arr with
810
-
| Some lon -> (
811
-
match find_entry_in_ifd Tag.gps_longitude_ref GPS exif with
812
-
| Some { value = VAscii "W"; _ } -> Some (-.lon)
813
-
| _ -> Some lon)
814
-
| None -> None)
815
-
| _ -> None
816
-
817
-
(** Get GPS altitude in meters (negative for below sea level) *)
818
-
let gps_altitude exif =
819
-
match find_entry_in_ifd Tag.gps_altitude GPS exif with
820
-
| Some e -> (
821
-
match get_rational e with
822
-
| Some alt -> (
823
-
match find_entry_in_ifd Tag.gps_altitude_ref GPS exif with
824
-
| Some { value = VByte [| 1 |]; _ } -> Some (-.alt)
825
-
| _ -> Some alt)
826
-
| None -> None)
827
-
| None -> None
828
-
829
-
(** {1 Pretty printing} *)
830
-
831
-
(** Convert value to string for display *)
832
-
let string_of_value = function
833
-
| VByte arr ->
834
-
String.concat " " (Array.to_list (Array.map string_of_int arr))
835
-
| VAscii s -> s
836
-
| VShort arr ->
837
-
String.concat " " (Array.to_list (Array.map string_of_int arr))
838
-
| VLong arr ->
839
-
String.concat " " (Array.to_list (Array.map Int32.to_string arr))
840
-
| VRational arr ->
841
-
String.concat " " (Array.to_list (Array.map (fun r ->
842
-
Printf.sprintf "%ld/%ld" r.numerator r.denominator) arr))
843
-
| VSbyte arr ->
844
-
String.concat " " (Array.to_list (Array.map string_of_int arr))
845
-
| VUndefined b ->
846
-
if Bytes.length b <= 16 then
847
-
String.concat " " (List.init (Bytes.length b) (fun i ->
848
-
Printf.sprintf "%02X" (Bytes.get_uint8 b i)))
849
-
else
850
-
Printf.sprintf "<%d bytes>" (Bytes.length b)
851
-
| VSshort arr ->
852
-
String.concat " " (Array.to_list (Array.map string_of_int arr))
853
-
| VSlong arr ->
854
-
String.concat " " (Array.to_list (Array.map Int32.to_string arr))
855
-
| VSrational arr ->
856
-
String.concat " " (Array.to_list (Array.map (fun r ->
857
-
Printf.sprintf "%ld/%ld" r.snumerator r.sdenominator) arr))
858
-
| VFloat arr ->
859
-
String.concat " " (Array.to_list (Array.map string_of_float arr))
860
-
| VDouble arr ->
861
-
String.concat " " (Array.to_list (Array.map string_of_float arr))
862
-
863
-
(** Convert entry to human-readable string *)
864
-
let string_of_entry entry =
865
-
Printf.sprintf "%s: %s"
866
-
(Tag.name_of_tag entry.tag entry.ifd)
867
-
(string_of_value entry.value)
868
-
869
-
(** Convert IFD to string *)
870
-
let string_of_ifd = function
871
-
| IFD0 -> "IFD0"
872
-
| IFD1 -> "IFD1"
873
-
| EXIF -> "EXIF"
874
-
| GPS -> "GPS"
875
-
| Interoperability -> "Interoperability"
876
-
877
-
(** Dump all EXIF data to string *)
878
-
let to_string exif =
879
-
let lines = List.map (fun entry ->
880
-
Printf.sprintf "[%s] %s"
881
-
(string_of_ifd entry.ifd)
882
-
(string_of_entry entry)) exif.entries
883
-
in
884
-
String.concat "\n" lines
-371
src/exif.mli
-371
src/exif.mli
···
1
-
(** Pure OCaml EXIF parsing library
2
-
3
-
Based on EXIF 2.32 specification and libexif reference implementation.
4
-
5
-
{1 Example Usage}
6
-
7
-
{[
8
-
(* Parse EXIF from raw APP1 data *)
9
-
let exif = Exif.parse_from_app1 app1_data in
10
-
11
-
(* Get camera make and model *)
12
-
let make = Exif.make exif in
13
-
let model = Exif.model exif in
14
-
15
-
(* Get GPS coordinates *)
16
-
let lat = Exif.gps_latitude exif in
17
-
let lon = Exif.gps_longitude exif in
18
-
]} *)
19
-
20
-
(** {1 Types} *)
21
-
22
-
(** Byte order for multi-byte values *)
23
-
type byte_order =
24
-
| Big_endian (** "MM" - Motorola byte order *)
25
-
| Little_endian (** "II" - Intel byte order *)
26
-
27
-
(** EXIF data formats (TIFF types) *)
28
-
type format =
29
-
| Byte (** 8-bit unsigned integer *)
30
-
| Ascii (** 8-bit byte containing 7-bit ASCII *)
31
-
| Short (** 16-bit unsigned integer *)
32
-
| Long (** 32-bit unsigned integer *)
33
-
| Rational (** Two LONGs: numerator and denominator *)
34
-
| Sbyte (** 8-bit signed integer *)
35
-
| Undefined (** 8-bit byte *)
36
-
| Sshort (** 16-bit signed integer *)
37
-
| Slong (** 32-bit signed integer *)
38
-
| Srational (** Two SLONGs: numerator and denominator *)
39
-
| Float (** Single precision IEEE float *)
40
-
| Double (** Double precision IEEE float *)
41
-
42
-
(** Image File Directory types *)
43
-
type ifd =
44
-
| IFD0 (** Primary image IFD *)
45
-
| IFD1 (** Thumbnail image IFD *)
46
-
| EXIF (** EXIF private tags IFD *)
47
-
| GPS (** GPS info IFD *)
48
-
| Interoperability (** Interoperability IFD *)
49
-
50
-
(** Rational number (numerator/denominator) *)
51
-
type rational = {
52
-
numerator : int32;
53
-
denominator : int32;
54
-
}
55
-
56
-
(** Signed rational number *)
57
-
type srational = {
58
-
snumerator : int32;
59
-
sdenominator : int32;
60
-
}
61
-
62
-
(** EXIF tag values *)
63
-
type value =
64
-
| VByte of int array
65
-
| VAscii of string
66
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| VShort of int array
67
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| VLong of int32 array
68
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| VRational of rational array
69
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| VSbyte of int array
70
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| VUndefined of bytes
71
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| VSshort of int array
72
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| VSlong of int32 array
73
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| VSrational of srational array
74
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| VFloat of float array
75
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| VDouble of float array
76
-
77
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(** A single EXIF entry *)
78
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type entry = {
79
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tag : int;
80
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ifd : ifd;
81
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format : format;
82
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components : int;
83
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value : value;
84
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}
85
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86
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(** Complete EXIF data *)
87
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type t = {
88
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byte_order : byte_order;
89
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entries : entry list;
90
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thumbnail : bytes option;
91
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}
92
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93
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(** {1 Tag Constants} *)
94
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95
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module Tag : sig
96
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(** IFD0/IFD1 tags *)
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val image_width : int
98
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val image_length : int
99
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val bits_per_sample : int
100
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val compression : int
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val photometric_interpretation : int
102
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val image_description : int
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val make : int
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val model : int
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val strip_offsets : int
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val orientation : int
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val samples_per_pixel : int
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val rows_per_strip : int
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val strip_byte_counts : int
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val x_resolution : int
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val y_resolution : int
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val planar_configuration : int
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val resolution_unit : int
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val transfer_function : int
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val software : int
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val date_time : int
117
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val artist : int
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val white_point : int
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val primary_chromaticities : int
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val jpeg_interchange_format : int
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val jpeg_interchange_format_length : int
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val ycbcr_coefficients : int
123
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val ycbcr_sub_sampling : int
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val ycbcr_positioning : int
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val reference_black_white : int
126
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val copyright : int
127
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val exif_ifd_pointer : int
128
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val gps_info_ifd_pointer : int
129
-
130
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(** EXIF IFD tags *)
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val exposure_time : int
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val f_number : int
133
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val exposure_program : int
134
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val spectral_sensitivity : int
135
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val iso_speed_ratings : int
136
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val oecf : int
137
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val sensitivity_type : int
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val exif_version : int
139
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val date_time_original : int
140
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val date_time_digitized : int
141
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val offset_time : int
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val offset_time_original : int
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val offset_time_digitized : int
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val components_configuration : int
145
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val compressed_bits_per_pixel : int
146
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val shutter_speed_value : int
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val aperture_value : int
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val brightness_value : int
149
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val exposure_bias_value : int
150
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val max_aperture_value : int
151
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val subject_distance : int
152
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val metering_mode : int
153
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val light_source : int
154
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val flash : int
155
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val focal_length : int
156
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val subject_area : int
157
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val maker_note : int
158
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val user_comment : int
159
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val sub_sec_time : int
160
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val sub_sec_time_original : int
161
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val sub_sec_time_digitized : int
162
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val flash_pix_version : int
163
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val color_space : int
164
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val pixel_x_dimension : int
165
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val pixel_y_dimension : int
166
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val related_sound_file : int
167
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val interoperability_ifd_pointer : int
168
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val flash_energy : int
169
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val spatial_frequency_response : int
170
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val focal_plane_x_resolution : int
171
-
val focal_plane_y_resolution : int
172
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val focal_plane_resolution_unit : int
173
-
val subject_location : int
174
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val exposure_index : int
175
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val sensing_method : int
176
-
val file_source : int
177
-
val scene_type : int
178
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val cfa_pattern : int
179
-
val custom_rendered : int
180
-
val exposure_mode : int
181
-
val white_balance : int
182
-
val digital_zoom_ratio : int
183
-
val focal_length_in_35mm_film : int
184
-
val scene_capture_type : int
185
-
val gain_control : int
186
-
val contrast : int
187
-
val saturation : int
188
-
val sharpness : int
189
-
val device_setting_description : int
190
-
val subject_distance_range : int
191
-
val image_unique_id : int
192
-
val camera_owner_name : int
193
-
val body_serial_number : int
194
-
val lens_specification : int
195
-
val lens_make : int
196
-
val lens_model : int
197
-
val lens_serial_number : int
198
-
val gamma : int
199
-
200
-
(** GPS tags *)
201
-
val gps_version_id : int
202
-
val gps_latitude_ref : int
203
-
val gps_latitude : int
204
-
val gps_longitude_ref : int
205
-
val gps_longitude : int
206
-
val gps_altitude_ref : int
207
-
val gps_altitude : int
208
-
val gps_time_stamp : int
209
-
val gps_satellites : int
210
-
val gps_status : int
211
-
val gps_measure_mode : int
212
-
val gps_dop : int
213
-
val gps_speed_ref : int
214
-
val gps_speed : int
215
-
val gps_track_ref : int
216
-
val gps_track : int
217
-
val gps_img_direction_ref : int
218
-
val gps_img_direction : int
219
-
val gps_map_datum : int
220
-
val gps_dest_latitude_ref : int
221
-
val gps_dest_latitude : int
222
-
val gps_dest_longitude_ref : int
223
-
val gps_dest_longitude : int
224
-
val gps_dest_bearing_ref : int
225
-
val gps_dest_bearing : int
226
-
val gps_dest_distance_ref : int
227
-
val gps_dest_distance : int
228
-
val gps_processing_method : int
229
-
val gps_area_information : int
230
-
val gps_date_stamp : int
231
-
val gps_differential : int
232
-
val gps_h_positioning_error : int
233
-
234
-
(** Get human-readable name for a tag *)
235
-
val name_of_tag : int -> ifd -> string
236
-
end
237
-
238
-
(** {1 Parsing} *)
239
-
240
-
(** Parse error *)
241
-
exception Parse_error of string
242
-
243
-
(** Parse complete EXIF data from raw TIFF-format bytes *)
244
-
val parse : bytes -> t
245
-
246
-
(** Parse EXIF data from a JPEG APP1 segment (with "Exif\x00\x00" prefix stripped) *)
247
-
val parse_from_app1 : bytes -> t
248
-
249
-
(** {1 Query Functions} *)
250
-
251
-
(** Find entry by tag in any IFD *)
252
-
val find_entry : int -> t -> entry option
253
-
254
-
(** Find entry by tag in specific IFD *)
255
-
val find_entry_in_ifd : int -> ifd -> t -> entry option
256
-
257
-
(** Get all entries for a specific IFD *)
258
-
val entries_in_ifd : ifd -> t -> entry list
259
-
260
-
(** {1 Value Extraction Helpers} *)
261
-
262
-
(** Get ASCII string value *)
263
-
val get_string : entry -> string option
264
-
265
-
(** Get single SHORT value *)
266
-
val get_short : entry -> int option
267
-
268
-
(** Get single LONG value *)
269
-
val get_long : entry -> int option
270
-
271
-
(** Get single RATIONAL value as float *)
272
-
val get_rational : entry -> float option
273
-
274
-
(** Get RATIONAL array as floats *)
275
-
val get_rationals : entry -> float array option
276
-
277
-
(** {1 Common Metadata Accessors} *)
278
-
279
-
(** Get camera make *)
280
-
val make : t -> string option
281
-
282
-
(** Get camera model *)
283
-
val model : t -> string option
284
-
285
-
(** Get software *)
286
-
val software : t -> string option
287
-
288
-
(** Get image description *)
289
-
val image_description : t -> string option
290
-
291
-
(** Get artist *)
292
-
val artist : t -> string option
293
-
294
-
(** Get copyright *)
295
-
val copyright : t -> string option
296
-
297
-
(** Get date/time original (when photo was taken) *)
298
-
val date_time_original : t -> string option
299
-
300
-
(** Get date/time digitized *)
301
-
val date_time_digitized : t -> string option
302
-
303
-
(** Get date/time (file modification) *)
304
-
val date_time : t -> string option
305
-
306
-
(** Get orientation (1-8) *)
307
-
val orientation : t -> int option
308
-
309
-
(** Get image width *)
310
-
val image_width : t -> int option
311
-
312
-
(** Get image height *)
313
-
val image_height : t -> int option
314
-
315
-
(** Get X resolution *)
316
-
val x_resolution : t -> float option
317
-
318
-
(** Get Y resolution *)
319
-
val y_resolution : t -> float option
320
-
321
-
(** Get resolution unit (1=none, 2=inch, 3=cm) *)
322
-
val resolution_unit : t -> int option
323
-
324
-
(** Get exposure time in seconds *)
325
-
val exposure_time : t -> float option
326
-
327
-
(** Get F-number *)
328
-
val f_number : t -> float option
329
-
330
-
(** Get ISO speed *)
331
-
val iso_speed : t -> int option
332
-
333
-
(** Get focal length in mm *)
334
-
val focal_length : t -> float option
335
-
336
-
(** Get focal length in 35mm equivalent *)
337
-
val focal_length_35mm : t -> int option
338
-
339
-
(** Get flash status *)
340
-
val flash : t -> int option
341
-
342
-
(** Get color space (1=sRGB, 65535=uncalibrated) *)
343
-
val color_space : t -> int option
344
-
345
-
(** Get EXIF version string *)
346
-
val exif_version : t -> string option
347
-
348
-
(** {1 GPS Accessors} *)
349
-
350
-
(** Get GPS latitude in decimal degrees (negative for South) *)
351
-
val gps_latitude : t -> float option
352
-
353
-
(** Get GPS longitude in decimal degrees (negative for West) *)
354
-
val gps_longitude : t -> float option
355
-
356
-
(** Get GPS altitude in meters (negative for below sea level) *)
357
-
val gps_altitude : t -> float option
358
-
359
-
(** {1 Pretty Printing} *)
360
-
361
-
(** Convert value to string for display *)
362
-
val string_of_value : value -> string
363
-
364
-
(** Convert entry to human-readable string *)
365
-
val string_of_entry : entry -> string
366
-
367
-
(** Convert IFD to string *)
368
-
val string_of_ifd : ifd -> string
369
-
370
-
(** Dump all EXIF data to string *)
371
-
val to_string : t -> string