exif

A tiny ISO-compliant C++ EXIF encoding and decoding library extended from easyexif (https://github.com/10imaging/easyexif) to additionally save EXIF metadata.

EXIF is a tiny, lightweight C++ library that parses basic information out of JPEG files. It uses only the std::string library and is otherwise pure C++. You pass it the binary contents of a JPEG file, and it parses several of the most important EXIF fields for you.

Why use this library? Include one .h file, compile one .cc file, and that's it.

Sometimes you just need to quickly extract basic information from a JPEG file's EXIF headers: the time the image was taken (not the file timestamp, the camera's internal time), the F-stop or exposure time, GPS information embedded in the EXIF file, what the camera make and model was, etc. Unfortunately, all the EXIF libraries out there are not very lightweight or easy to integrate into larger programs. EXIF aims to solve that problem, and is released under a very liberal BSD License for use practically anywhere.

The only two files you need for your project are exif.cpp and exif.h. There are no dependencies on any build system or external libraries.

Who uses this library?

• Blackberry's BBM messenger.
• Altova Software.
• Subsurface.
• Loom SDK

Features:

1. Supports common Exif fields including GPS, ISO speed, etc.
2. Extensively documented in the source
3. Valgrind tested for memory leaks
4. Handles corrupt JPEGs
5. Compiles without complaints using -Wall -Wextra -Werror -pedantic -ansi on gcc v4.8.2
6. Loads and saves EXIF meta-data - easyexif only loads EXIF metadata
7. Handles all IFD types
8. Encodes tags for saving your own EXIF tagged files (not supported by the original easyexif)

License

BSD. Free for personal and commercial use.

Contributions

Reasonable pull requests are gladly accepted. Please ensure that you have run the following steps before submitting a patch:

1. clang-format the source files, using the default style (Google).
2. Run test.sh to make sure test images are being parsed correctly.
3. Compile and run demo using valgrind --leak-check=full to ensure that there are no memory leaks.
4. Add yourself to the contributors list in CONTRIBUTORS and README.md.
5. For misbehaving images, please try to include a test image that misbehaves in the test-images folder.

The following people have committed patches to https://github.com/10imaging/exif.

• Tomas Volf
• Seth Fowler
• Val Malykh
• Carlos Apablaza Brito
• Simon Fuhrmann
• Toshiaki Ohkuma
• pet.b.hunt
• Jason Moey
• Victor Vedovato (victorv)
• Shari Vedovato (sharived)

Example:

See exifprint.cpp for other Exif fields.

  #include "exif.h"

  EXIFInfo result;
  result.parseFrom(JPEGFileBuffer, BufferSize);

  printf("Camera make       : %s\n", result.Make.c_str());
  printf("Camera model      : %s\n", result.Model.c_str());
  printf("Software          : %s\n", result.Software.c_str());
  printf("Bits per sample   : %d\n", result.BitsPerSample);
  printf("Image width       : %d\n", result.ImageWidth);
  printf("Image height      : %d\n", result.ImageHeight);
  printf("Image description : %s\n", result.ImageDescription.c_str());
  printf("Image orientation : %d\n", result.Orientation);
  printf("Image copyright   : %s\n", result.Copyright.c_str());
  printf("Image date/time   : %s\n", result.DateTime.c_str());
  printf("Original date/time: %s\n", result.DateTimeOriginal.c_str());
  printf("Digitize date/time: %s\n", result.DateTimeDigitized.c_str());
  printf("Subsecond time    : %s\n", result.SubSecTimeOriginal.c_str());
  printf("Exposure time     : 1/%d s\n", (unsigned) (1.0/result.ExposureTime));
  printf("F-stop            : f/%.1f\n", result.FNumber);
  printf("ISO speed         : %d\n", result.ISOSpeedRatings);
  printf("Subject distance  : %f m\n", result.SubjectDistance);
  printf("Exposure bias     : %f EV\n", result.ExposureBiasValue);
  printf("Flash used?       : %d\n", result.Flash);
  printf("Metering mode     : %d\n", result.MeteringMode);
  printf("Lens focal length : %f mm\n", result.FocalLength);
  printf("35mm focal length : %u mm\n", result.FocalLengthIn35mm);
  printf("GPS Latitude      : %f deg\n", result.GeoLocation.Latitude);
  printf("GPS Longitude     : %f deg\n", result.GeoLocation.Longitude);
  printf("GPS Altitude      : %f m\n", result.GeoLocation.Altitude);