A Quick Analysis of EXIF data from Apple’s iPhone 4S Camera Samples
In the course of doing smartphone reviews for AnandTech, I’ve taken a lot of photos for the expressed purpose of comparing camera quality. I don’t have an exact number, but it’s an absurd number of images, and of those, maybe 20% or so actually get published. We reviewed the iPhone 4S and discussed its camera at length in our review, but one of the things that piqued my attention was Apple’s claim that they had were sharing untouched, direct-from-the-iPhone samples online (at the bottom). In case you want all of the images, I’ve uploaded a zip here locally.
What’s interesting is that by default, iOS captures geolocation data on each image capture unless you decline the location services request on initial launch. I was curious to find out just how untouched these images were and whether all the EXIF data was left intact, including the GPS location data. Clearly these photos were taken at places that are either some engineer’s favorite hideouts, or possibly much more. Also, there’s that ever looming question of when they were taken, and whether there’s any chance anyone could’ve seen Apple employees taking photos with an unreleased iDevice at some scenic location.
You can analyze EXIF data in any number of image manipulation packages, and increasingly desktop OSes are exposing this data directly (Finder, Explorer, e.t.c.) but for quick analysis I turned to exifdata.com which does a nice job visualizing everything. Alternatively one can just dump the EXIF data using libraries like the very popular exiftool.
Image 1 – IMG1031
Here’s the dump from one of Apple’s demo images, “IMG_1031.JPG” which is the squirrel photo shown during the announcement event. There’s all the standard data included in the full headers, and you can see specifications such as focal length, exposure time, ISO, model, and the software (iOS 5) used. There are some other fields as well.
SubjectArea I believe corresponds to either where the face detection routine selected an AE/AF target with highest confidence value (most likely to be a face), or where the image was focused using tap to focus. The iPhone 4S also includes some new fields at the very bottom such as 35mm equivalent focal length, field of view, hyperfocal distance (at half this distance, all objects and further meet image plane blur criterion and appear in focus – this half trips people up), and even circle of confusion diameter (blur size/circle of confusion). These values at the very end appear to be specific to the iPhone 4S (and possibly its H4 ISP) and aren’t part of the JEITA EXIF 2.2 specification.
ExifTool Version Number : 8.68 File Name : IMG_1031.JPG Directory : . File Size : 3.1 MB File Modification Date/Time : 2011:10:05 01:43:44-07:00 File Permissions : rw-r--r-- File Type : JPEG MIME Type : image/jpeg Exif Byte Order : Big-endian (Motorola, MM) Make : Apple Camera Model Name : iPhone 4S Orientation : Rotate 180 X Resolution : 72 Y Resolution : 72 Resolution Unit : inches Software : 5.0 Modify Date : 2011:08:24 13:13:33 Y Cb Cr Positioning : Centered Exposure Time : 1/286 F Number : 2.4 Exposure Program : Program AE ISO : 64 Exif Version : 0221 Date/Time Original : 2011:08:24 13:13:33 Create Date : 2011:08:24 13:13:33 Components Configuration : Y, Cb, Cr, - Shutter Speed Value : 1/286 Aperture Value : 2.4 Brightness Value : 6.992671928 Metering Mode : Multi-segment Flash : Auto, Did not fire Focal Length : 4.3 mm Subject Area : 1631 1223 881 881 Flashpix Version : 0100 Color Space : sRGB Exif Image Width : 3264 Exif Image Height : 2448 Sensing Method : One-chip color area Exposure Mode : Auto White Balance : Auto Focal Length In 35mm Format : 35 mm Scene Capture Type : Standard Sharpness : Normal GPS Latitude Ref : North GPS Longitude Ref : West GPS Altitude Ref : Above Sea Level GPS Time Stamp : 21:08:30 GPS Img Direction Ref : True North GPS Img Direction : 346.4727273 Compression : JPEG (old-style) Thumbnail Offset : 908 Thumbnail Length : 12311 Image Width : 3264 Image Height : 2448 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 Altitude : 1222 m Above Sea Level GPS Latitude : 37 deg 44' 10.80" N GPS Longitude : 119 deg 35' 58.80" W GPS Position : 37 deg 44' 10.80" N, 119 deg 35' 58.80" W Image Size : 3264x2448 Scale Factor To 35 mm Equivalent: 8.2 Shutter Speed : 1/286 Thumbnail Image : (Binary data 12311 bytes, use -b option to extract) Circle Of Confusion : 0.004 mm Field Of View : 54.4 deg Focal Length : 4.3 mm (35 mm equivalent: 35.0 mm) Hyperfocal Distance : 2.08 m Light Value : 11.3
If you look at this data a few things pop out. There really is GPS location data inside, and just like before the iDevice also encodes what direction the phone was pointing (compass data) when the image was captured.
This first photo was captured in Yosemite National Park on August 24th 2011, a full one month and 10 days before its announcement on October 4. Interesting.
Image 2 – IMG1664
This second image is of some waves breaking on a rocky beach and shows very nice detail. Just like the first image, it too includes GPS data and the creation date.
Make : Apple Camera Model Name : iPhone 4S Orientation : Rotate 180 Date/Time Original : 2011:08:29 18:50:23 Create Date : 2011:08:29 18:50:23 GPS Latitude Ref : North GPS Longitude Ref : West GPS Altitude Ref : Below Sea Level GPS Time Stamp : 02:27:00 GPS Img Direction Ref : True North GPS Img Direction : 357.1590909 GPS Altitude : 0 m Above Sea Level GPS Latitude : 38 deg 26' 28.20" N GPS Longitude : 123 deg 7' 36.00" W GPS Position : 38 deg 26' 28.20" N, 123 deg 7' 36.00" W
I’ve truncated the exported data for this image since the same format as the previous one. Note zero feet above sea level, indeed this checks out.
This photo was taken at goat rock beach on August 29th, five days after the first image, and one month 5 days before the announcement. What’s intense about this image is that if you study the google satellite view enough, then take into account the pointing direction, you can actually see the rock in the photograph.
Image 3 – IMG0032
This image is a landscape photo with a waterfall in the distance.
Make : Apple Camera Model Name : iPhone 4S Orientation : Horizontal (normal) Date/Time Original : 2011:08:25 09:27:36 Create Date : 2011:08:25 09:27:36 GPS Latitude Ref : North GPS Longitude Ref : West GPS Altitude Ref : Above Sea Level GPS Time Stamp : 17:26:10 GPS Img Direction Ref : True North GPS Img Direction : 254.5312024 GPS Altitude : 1192 m Above Sea Level GPS Latitude : 37 deg 44' 38.40" N GPS Longitude : 119 deg 35' 30.60" W GPS Position : 37 deg 44' 38.40" N, 119 deg 35' 30.60" W
This one also includes the GPS location and pointing data.
Upon inspection, we can see this photo was taken also at Yosemite National Park and on August 25th 2011. It seems very likely this was taken by the same person who took the squirrel photo, given the fact that it’s a day later and in the same region in the park – perhaps a camping trip or something?
Image 4 – IMG1295
This image is of a person holding a flower up to the camera showing shallow depth of field and some serious bokeh. The subject is the same as shown in the 1080p video sample Apple provides, and appears to lack GPS data of any kind, but was taken on August 29th.
Make : Apple Camera Model Name : iPhone 4S Orientation : Horizontal (normal) Date/Time Original : 2011:08:29 15:54:02 Create Date : 2011:08:29 15:54:02
Image 5 – IMG0945
This image looks almost like a test scene, and includes some potted herbs, drawers, fruits, lemons, and a bunch of different knick knacks. The EXIF data for this one includes GPS data.
Make : Apple Camera Model Name : iPhone 4S Orientation : Horizontal (normal) Date/Time Original : 2011:08:30 14:01:03 Create Date : 2011:08:30 14:01:03 GPS Latitude Ref : North GPS Longitude Ref : East GPS Altitude Ref : Above Sea Level GPS Time Stamp : 13:25:21 GPS Img Direction Ref : True North GPS Img Direction : 21.31747484 GPS Altitude : 342.1 m Above Sea Level GPS Latitude : 50 deg 55' 6.60" N GPS Longitude : 14 deg 3' 24.00" E GPS Position : 50 deg 55' 6.60" N, 14 deg 3' 24.00" E
So far the images we’ve seen have been from just inside the US – this image is from the Königstein Fortress in Germany of all places, and was taken on August 30th.
This one is particularly interesting since it’s a great demonstration photo but also is the only sample image not taken in the US.
Image 6 – IMG1401
This image also has no GPS data, which means it possibly was taken by the same iPhone 4S as number 4 (and this user disabled location services for the camera app), or just someone else who was likewise cautious to not include position. This image is a macro of some flowers.
Make : Apple Camera Model Name : iPhone 4S Orientation : Horizontal (normal) Date/Time Original : 2011:08:29 17:30:26 Create Date : 2011:08:29 17:30:26
This image was taken on August 29th, however.
Image 7 – IMG1720
Likewise, this one also lacks GPS data, but shows a beach at dusk (thus, west coast) and appears to have been taken likewise on August 29th in the evening.
Make : Apple Camera Model Name : iPhone 4S Orientation : Horizontal (normal) Date/Time Original : 2011:08:29 19:28:56 Create Date : 2011:08:29 19:28:56
Image 8 – IMG0940
The last image shows the same hot air balloon as shown in the 1080p video sample, and includes GPS data. We can see where this video (and likely image 4) was taken.
Make : Apple Camera Model Name : iPhone 4S Orientation : Rotate 180 Date/Time Original : 2011:08:30 10:33:45 Create Date : 2011:08:30 10:33:45 GPS Latitude Ref : North GPS Longitude Ref : West GPS Altitude Ref : Above Sea Level GPS Time Stamp : 18:48:01 GPS Img Direction Ref : True North GPS Img Direction : 270.9027778 GPS Altitude : 31 m Above Sea Level GPS Latitude : 38 deg 30' 13.20" N GPS Longitude : 122 deg 46' 21.00" W GPS Position : 38 deg 30' 13.20" N, 122 deg 46' 21.00" W
Oddly enough image 4 and image 8 were taken on different days, so this possibly is a different location. That said, the location appears to be the Kendall-Jackson winery right off the 101.
Like the beach photo, this is just up the coast from San Francisco. The photo was taken August 30th as well.
Apple took sample images for its iPhone 4S presentation between the dates of August 24th and August 30th, a little over one month before the public unveiling. It’s interesting to note that had you been fortuitous enough to be in Yosemite National Park on the 24th or 25th, you might have by chance seen an iPhone 4S snapping photos of scenery and squirrels. Other locations near San Francisco seem logical given Apple’s location in Cupertino, CA, leaving the photo from Germany an odd outlier.
It seems that for all the scrutiny placed on bars surrounding 1 infinite loop, being in picturesque locales one month before an iPhone unveiling is quite possibly another logical strategy for spotting an unreleased iPhone.
I have to come full circle and say that I’m impressed Apple really didn’t scrub data from its sample images. This is something even I do to provide some location anonymity in the course of uploading sample images, though as of late I’ve become sloppy with scrubbing all the GPS data from EXIF for each sample image.