Erlang EXIF Library

Building and Testing

Prerequisites

• Erlang/OTP R16 or higher (17 or higher for EXIF in maps)
• rebar 2.x

To build the application and run the test suite, use rebar like so:

$ rebar compile
$ rebar ct

Usage

To add erlang-exif as a dependency to your rebar-based project, simply add the following to your rebar.config file, then run the rebar get-deps command to retrieve it.

{deps, [
    {exif, ".*", {git, "https://github.com/nlfiedler/erlang-exif", {tag, "2.0.3"}}}
]}.

Example

The exif:read(Path) function actually calls exif:read(Path, dict) (for backward compatibility).

The exif:read(Path, ReturnType) function returns {ok, Exif} where Exif is a dict:dict() or a map of the values read from the JPEG image. ReturnType has two valid values: dict and maps. If no such values are present, the structure will be empty. However, if there was an error, an {error, Reason} tuple will be returned, where Reason is nearly always invalid_exif.

case exif:read(Path, dict) of
    {error, Reason} ->
        error_logger:error_msg("Unable to read EXIF data from ~s, ~p~n", [Path, Reason]);
    {ok, ExifData} ->
        case dict:find(date_time_original, ExifData) of
            {ok, Original} ->
                % do something with the date...
                ok;
            error ->
                error_logger:info_msg("No original date available")
        end
end.

Two more functions are present: exif:read_binary/1 and exif:read_binary/2 which are equivalents of exif:read/1,2. They accept actual file in binary format as a first argument, instead of a path.