Interpreting GPS info of exif data from photo in python

Question

I am writing a small program to get the GPS info of a iphone jpg photo.

The library I am using is the PIL in python. Now I am able to get the GPSInfo, which is something like:

{1: 'N', 
 2: ((1, 1), (20, 1), (5365, 100)), 
 3: 'E', 
 4: ((103, 1), (41, 1), (1052, 100)), 
 5: 0, 
 6: (43, 1), 
 7: ((15, 1), (32, 1), (7, 1)), 
 16: 'T', 
 17: (77473, 452), 
 29: '2013:10:25'}

How can I interpret this? And I notice the tag is not continuous, so is there any cheating sheet which I can refer to in order to get a better understanding of all the number tags and what they mean? Thank you!

UPDATES

Sorry, I have figured it out. In the PIL lib, there is a GPSTAGS.get() function which can help me decode the key in gps info. Thank you guys!

gpsinfo = {}
for key in exif['GPSInfo'].keys():
    decode = ExifTags.GPSTAGS.get(key,key)
    gpsinfo[decode] = exif['GPSInfo'][key]
print gpsinfo

and here is the result

{'GPSTimeStamp': ((15, 1), (32, 1), (7, 1)), 
 'GPSImgDirectionRef': 'T', 
 'GPSImgDirection': (77473, 452), 
 'GPSLongitude': ((103, 1), (41, 1), (1052, 100)), 
 'GPSLatitudeRef': 'N', 29: '2013:10:25', 
 'GPSAltitude': (43, 1), 
 'GPSLatitude': ((1, 1), (20, 1), (5365, 100)), 
 'GPSLongitudeRef': 'E', 
 'GPSAltitudeRef': 0}

Answer 1

Use exifread module.

Here is a very helpful gist

import exifread as ef


# barrowed from 
# https://gist.github.com/snakeye/fdc372dbf11370fe29eb 
def _convert_to_degress(value):
    """
    Helper function to convert the GPS coordinates stored in the EXIF to degress in float format
    :param value:
    :type value: exifread.utils.Ratio
    :rtype: float
    """
    d = float(value.values[0].num) / float(value.values[0].den)
    m = float(value.values[1].num) / float(value.values[1].den)
    s = float(value.values[2].num) / float(value.values[2].den)

    return d + (m / 60.0) + (s / 3600.0)


def getGPS(filepath):
    '''
    returns gps data if present other wise returns empty dictionary
    '''
    with open(filepath, 'r') as f:
        tags = ef.process_file(f)
        latitude = tags.get('GPS GPSLatitude')
        latitude_ref = tags.get('GPS GPSLatitudeRef')
        longitude = tags.get('GPS GPSLongitude')
        longitude_ref = tags.get('GPS GPSLongitudeRef')
        if latitude:
            lat_value = _convert_to_degress(latitude)
            if latitude_ref.values != 'N':
                lat_value = -lat_value
        else:
            return {}
        if longitude:
            lon_value = _convert_to_degress(longitude)
            if longitude_ref.values != 'E':
                lon_value = -lon_value
        else:
            return {}
        return {'latitude': lat_value, 'longitude': lon_value}
    return {}


file_path = 'file path of the file'    
gps = getGPS(file_path)
print gps