Exploring EXIF – Harley Turan

According to iOS’ Photos application, I’ve taken 73,281 photos over the past 14 years of owning an iPhone.

Each one of those images doesn't just contain the photo you see as you scroll through the Photos app — it contains a wealth of information stored encoded directly into the image file itself. It details useful metadata such as where the photo was taken (so that you can view your photos on a map at a later date), the time and date the image was taken at, which lens and zoom levels were used, the exposure, ISO, and aperture, amongst many others.

There are many, many tools for viewing this information. Whichever app you use to manage your photos will display this metadata alongside the image, such as in iOS 16 here:

This metadata is called EXIF (Exchangeable Image File Format) and is stored inside of the photo files themselves, appearing right at the start of the image (before any image data appears). If we inspect the contents of a JPEG photo directly exported from an iPhone, we see the EXIF data marker (FFE1) appear directly after the JPEG Start of Image marker (FFD8):

You‘ll be pleased to know this piece won't be spent going over every byte in the image above. Instead, we’ll be looking into what a photo contains, and the various ways in which we can display, query, and interact with the data therein.

What‘s in a photo?

The following visualization shows the vast amount of information stored within a single image. Feel free to pick from the curated examples from my personal photo library, or select your own image to view the EXIF data stored. Note that any images selected remain client-side and never leave your web browser. Client-side EXIF parsing is handled by the ExifReader library by Mattias Wallander.

Bits Per Sample

Image Height

1280px

Image Width

960px

Color Components

Subsampling

YCbCr4:2:0 (2 2)

Make

Apple

Model

iPhone 12 Pro

Orientation

top-left

XResolution

YResolution

ResolutionUnit

inches

Software

16.6

DateTime

2023:08:13 13:07:57

HostComputer

iPhone 12 Pro

TileWidth

512

TileLength

512

YCbCrPositioning

centered

Exif IFD Pointer

258

GPS Info IFD Pointer

2224

ExposureTime

1/856

FNumber

f/2

ExposureProgram

Normal program

ISOSpeedRatings

ExifVersion

0232

DateTimeOriginal

2023:08:13 13:07:57

DateTimeDigitized

2023:08:13 13:07:57

OffsetTime

+01:00

OffsetTimeOriginal

+01:00

OffsetTimeDigitized

+01:00

ComponentsConfiguration

ShutterSpeedValue

1/856

ApertureValue

2.00

BrightnessValue

9.10714795263233

ExposureBiasValue

MeteringMode

Pattern

Flash

Flash did not fire, compulsory flash mode

FocalLength

6 mm

SubjectArea

Rectangle; X: 2004, Y: 1514, width: 2318, height: 1393

MakerNote

[Raw maker note data]

SubSecTime

524

SubSecTimeOriginal

524

SubSecTimeDigitized

524

FlashpixVersion

0100

ColorSpace

Uncalibrated

PixelXDimension

4032

PixelYDimension

3024

SensingMethod

One-chip color area sensor

SceneType

A directly photographed image

ExposureMode

Auto exposure

WhiteBalance

Auto white balance

FocalLengthIn35mmFilm

SceneCaptureType

Standard

LensSpecification

1.5399999618512084-6 mm f/2.4

LensMake

Apple

LensModel

iPhone 12 Pro back triple camera 6mm f/2

CompositeImage

General Composite Image

GPSLatitudeRef

North latitude

GPSLatitude

51.11505833333334

GPSLongitudeRef

East longitude

GPSLongitude

0.5824055555555555

GPSAltitudeRef

Sea level

GPSAltitude

58.61263655152052 m

GPSSpeedRef

Kilometers per hour

GPSSpeed

GPSImgDirectionRef

True direction

GPSImgDirection

183.541214057508

GPSDestBearingRef

True direction

GPSDestBearing

183.541214057508

GPSHPositioningError

3.5355339046563916

Preferred CMM type

Apple

Profile Version

4.0.0

Profile/Device class

Input Device profile

Color Space

RGB

Connection Space

XYZ

ICC Profile Date

2016-01-01T00:00:00.000Z

ICC Signature

acsp

Primary Platform

Apple

Device Manufacturer

Apple

Device Model Number