What information is stored in EFIX/JPEG photos taken on the iPhone with geotagging enabled?

Question

I know that some of this data is viewable in iPhoto, such as latitude, longitude, and altitude, but is there more than this available? More specifically I am wanting to get the direction of the image as well, which is part of the EXIF format. Or does something other than geotagging need to be enabled (something to do with the compass)?

Answer 1

I suggest installing the command line tool exif. You can get it through Mac Ports by executing port install exif as root.

Here's an example of the exif info stored in a photo I took on an iPod Touch:

bash:$ exif Oct\ 9\,\ 2010/IMG_0038.JPG 
EXIF tags in 'Oct 9, 2010/IMG_0018.JPG' ('Motorola' byte order):
--------------------+----------------------------------------------------------
Tag                 |Value
--------------------+----------------------------------------------------------
Manufacturer        |Apple
Model               |iPod touch
Orientation         |right - top
x-Resolution        |72.00
y-Resolution        |72.00
Resolution Unit     |Inch
Software            |4.1
Date and Time       |2010:10:06 17:43:43
YCbCr Positioning   |centered
Compression         |JPEG compression
x-Resolution        |72.00
y-Resolution        |72.00
Resolution Unit     |Inch
Exposure Time       |1/120 sec.
FNumber             |f/2.4
Exposure Program    |Normal program
ISO Speed Ratings   |320
Exif Version        |Exif Version 2.21
Date and Time (origi|2010:10:06 17:43:43
Date and Time (digit|2010:10:06 17:43:43
Components Configura|Y Cb Cr -
Shutter speed       |6.91 EV (1/120 sec.)
Aperture            |2.53 EV (f/2.4)
Metering Mode       |Average
Flash               |No flash function
Focal Length        |3.9 mm
FlashPixVersion     |FlashPix Version 1.0
Color Space         |sRGB
PixelXDimension     |640
PixelYDimension     |480
Sensing Method      |One-chip color area sensor
Exposure Mode       |Auto exposure
White Balance       |Auto white balance
Scene Capture Type  |Standard
Sharpness           |Normal
North or South Latit|N
Latitude            |44.00, 22.12, 0.00
East or West Longitu|W
Longitude           |56.00, 23.98, 0.00
GPS time (atomic clo|17:43:41.60
--------------------+----------------------------------------------------------
EXIF data contains a thumbnail (10215 bytes).

I don't think the iPod Touch has the same capabilities as an iPhone regarding GPS.

It looks like an iPhone will have the data 'GPSImg Direction' as well, which sounds like what you want. I don't think you have to do anything special to enable it, as I haven't found much info on this through searching.

Answer 2

Okay, good news :). The direction is stored. Here's what I was able to get from a photo taken from an iphone (with location services and compass turned on) using the ExifTool mentioned by @rwong.

ExifTool Version Number         : 8.34
File Name                       : photo.JPG
Directory                       : C:/Documents and Settings/user/My Document
s/Downloads
File Size                       : 349 kB
File Modification Date/Time     : 2010:10:19 14:05:39-06:00
File Permissions                : rw-rw-rw-
File Type                       : JPEG
MIME Type                       : image/jpeg
JFIF Version                    : 1.01
Exif Byte Order                 : Big-endian (Motorola, MM)
Image Description               : Back Camera
Make                            : Apple
Camera Model Name               : iPhone
Orientation                     : Horizontal (normal)
X Resolution                    : 72
Y Resolution                    : 72
Resolution Unit                 : inches
Software                        : 4.0.1
Modify Date                     : 2010:10:19 14:00:52
Y Cb Cr Positioning             : Centered
Exposure Time                   : 1/146
F Number                        : 2.4
Exposure Program                : Program AE
ISO                             : 80
Exif Version                    : 0221
Date/Time Original              : 2010:10:19 14:00:52
Create Date                     : 2010:10:19 14:00:52
Shutter Speed Value             : 1/146
Aperture Value                  : 2.4
Metering Mode                   : Average
Flash                           : Off, Did not fire
Focal Length                    : 3.9 mm
Subject Area                    : 1295 967 699 696
Flashpix Version                : 0100
Color Space                     : sRGB
Exif Image Width                : 1296
Exif Image Height               : 968
Sensing Method                  : One-chip color area
Exposure Mode                   : Auto
White Balance                   : Auto
Scene Capture Type              : Standard
Sharpness                       : Hard
GPS Latitude Ref                : North
GPS Longitude Ref               : West
GPS Time Stamp                  : 14:00:46.81
GPS Img Direction Ref           : True North
GPS Img Direction               : 32.52336904
Image Width                     : 1296
Image Height                    : 968
Encoding Process                : Baseline DCT, Huffman coding
Bits Per Sample                 : 8
Color Components                : 3
Y Cb Cr Sub Sampling            : YCbCr4:2:0 (2 2)
Aperture                        : 2.4
GPS Latitude                    : 45 deg 14' 58.20" N
GPS Longitude                   : 121 deg 39' 4.80" W
GPS Position                    : 45 deg 14' 58.20" N, 121 deg 39' 4.80" W
Image Size                      : 1296x968
Shutter Speed                   : 1/146
Focal Length                    : 3.9 mm
Light Value                     : 10.0