Exploring EXIF – Harley Turan
In response to iOS’ Photographs software, I’ve taken 73,281 images over the previous 14 years of proudly owning an iPhone.
Every a kind of photos does not simply include the picture you see as you scroll by the Photographs app — it incorporates a wealth of data saved encoded immediately into the picture file itself. It particulars helpful metadata comparable to the place the picture was taken (with the intention to view your images on a map at a later date), the time and date the picture was taken at, which lens and zoom ranges had been used, the publicity, ISO, and aperture, amongst many others.
There are a lot of, many instruments for viewing this data. Whichever app you employ to handle your images will show this metadata alongside the picture, comparable to in iOS 16 right here:
This metadata is named EXIF (Exchangeable Image File Format) and is saved inside the picture recordsdata themselves, showing proper at the beginning of the picture (earlier than any picture information seems). If we examine the contents of a JPEG picture immediately exported from an iPhone, we see the EXIF information marker (FFE1) seem immediately after the JPEG Begin of Picture marker (FFD8):
You‘ll be happy to know this piece will not be spent going over each byte within the picture above. As an alternative, we’ll be wanting into what a photograph incorporates, and the assorted methods by which we are able to show, question, and work together with the information therein.
What‘s in a photograph?
The next visualization exhibits the huge quantity of data saved inside a single picture. Be happy to select from the curated examples from my private picture library, or choose your individual picture to view the EXIF information saved. Observe that any photos chosen stay client-side and by no means depart your internet browser. Shopper-side EXIF parsing is dealt with by the ExifReader library by Mattias Wallander.
Subsampling
YCbCr4:2:0 (2 2)
DateTime
2023:08:13 13:07:57
HostComputer
iPhone 12 Professional
ExposureProgram
Regular program
DateTimeOriginal
2023:08:13 13:07:57
DateTimeDigitized
2023:08:13 13:07:57
OffsetTimeDigitized
+01:00
BrightnessValue
9.10714795263233
Flash
Flash didn’t hearth, obligatory flash mode
SubjectArea
Rectangle; X: 2004, Y: 1514, width: 2318, peak: 1393
MakerNote
[Raw maker note data]SensingMethod
One-chip colour space sensor
SceneType
A immediately photographed picture
ExposureMode
Auto publicity
WhiteBalance
Auto white steadiness
LensSpecification
1.5399999618512084-6 mm f/2.4
LensModel
iPhone 12 Professional again triple digital camera 6mm f/2
CompositeImage
Basic Composite Picture
GPSLatitudeRef
North latitude
GPSLatitude
51.11505833333334
GPSLongitudeRef
East longitude
GPSLongitude
0.5824055555555555
GPSAltitude
58.61263655152052 m
GPSSpeedRef
Kilometers per hour
GPSImgDirectionRef
True course
GPSImgDirection
183.541214057508
GPSDestBearingRef
True course
GPSDestBearing
183.541214057508
GPSHPositioningError
3.5355339046563916
Profile/System class
Enter System profile
ICC Profile Date
2016-01-01T00:00:00.000Z