get_lat_lon_exif_pil.py

import sys

from PIL import Image
from PIL.ExifTags import TAGS, GPSTAGS

def get_exif_data(image):
    """Returns a dictionary from the exif data of an PIL Image item. Also converts the GPS Tags"""
    exif_data = {}
    info = image._getexif()
    if info:
        for tag, value in info.items():
            decoded = TAGS.get(tag, tag)
            if decoded == "GPSInfo":
                gps_data = {}
                for gps_tag in value:
                    sub_decoded = GPSTAGS.get(gps_tag, gps_tag)
                    gps_data[sub_decoded] = value[gps_tag]

                exif_data[decoded] = gps_data
            else:
                exif_data[decoded] = value

    return exif_data
	
def _convert_to_degress(value):
    """Helper function to convert the GPS coordinates stored in the EXIF to degress in float format"""
    deg_num, deg_denom = value[0]
    d = float(deg_num) / float(deg_denom)

    min_num, min_denom = value[1]
    m = float(min_num) / float(min_denom)

    sec_num, sec_denom = value[2]
    s = float(sec_num) / float(sec_denom)
    
    return d + (m / 60.0) + (s / 3600.0)

def get_lat_lon(exif_data):
    """Returns the latitude and longitude, if available, from the provided exif_data (obtained through get_exif_data above)"""
    lat = None
    lon = None

    if "GPSInfo" in exif_data:		
        gps_info = exif_data["GPSInfo"]

        gps_latitude = gps_info.get("GPSLatitude")
        gps_latitude_ref = gps_info.get('GPSLatitudeRef')
        gps_longitude = gps_info.get('GPSLongitude')
        gps_longitude_ref = gps_info.get('GPSLongitudeRef')

        if gps_latitude and gps_latitude_ref and gps_longitude and gps_longitude_ref:
            lat = _convert_to_degress(gps_latitude)
            if gps_latitude_ref != "N":                     
                lat *= -1

            lon = _convert_to_degress(gps_longitude)
            if gps_longitude_ref != "E":
                lon *= -1

    return lat, lon


################
# Example ######
################
if __name__ == "__main__":
    # load an image through PIL's Image object
    if len(sys.argv) < 2:
        print "Error! No image file specified!"
        print "Usage: %s <filename>" % sys.argv[0]
        sys.exit(1)

    image = Image.open(sys.argv[1])
    exif_data = get_exif_data(image)
    print get_lat_lon(exif_data)

sec_num, sec_denom = value[1]
must be
sec_num, sec_denom = value[2]

-> https://github.com/collective/collective.geo.exif/blob/master/collective/geo/exif/readexif.py

If you are using something like ExifTool to write data, it is easier (script-wise) to NOT populate N and E if the values are positive (that was my case anyway). I think those are safe assumptions to make IMO. I suggest the following changes

    if gps_info is not None:
        gps_latitude = gps_info.get("GPSLatitude", None)
        gps_latitude_ref = gps_info.get('GPSLatitudeRef', 'N')
        gps_longitude = gps_info.get('GPSLongitude', None)
        gps_longitude_ref = gps_info.get('GPSLongitudeRef', 'E')

@cleder : The evil copy-paste strikes again! Fixed now, thanks.

Could you offer some direction on how I might modify this script to extract lat/long from a batch of images? I'm new to Python (Python3, at that).

you can do much much shorter and clear :

import PIL.Image

get_float = lambda x: float(x[0]) / float(x[1])
def convert_to_degrees(value):
    d = get_float(value[0])
    m = get_float(value[1])
    s = get_float(value[2])
    return d + (m / 60.0) + (s / 3600.0)

def get_lat_lon(info):
    try:
        gps_latitude = info[34853][2]
        gps_latitude_ref = info[34853][1]
        gps_longitude = info[34853][4]
        gps_longitude_ref = info[34853][3]
        lat = convert_to_degrees(gps_latitude)
        if gps_longitude_ref != "N":
            lat *= -1

        lon = convert_to_degrees(gps_longitude)
        if gps_longitude_ref != "E":
            lon *= -1
        return lat, lon
    except KeyError:
        return None

This was super useful, thank you.

from using (lat,long) values,could you have any idea about how to find location of each pixel values of that image or grids of image??