When you shared an iPhone taken photo, what else did you reveal?

Exchangeable image file format (Exif) is a specification for the image file format used by digital cameras. The specification uses the existing JPEG, TIFF Rev. 6.0, and RIFF WAV file formats, with the addition of specific metadata tags. It is not supported in JPEG 2000, PNG, or GIF.

When you shared an iPhone taken photo online, it not only shows the pixel, but also when, where, and how you took the photo! Because the Exif metadata tag in those iPhone taken photo is un-believable detailed!!

Here is one example of EXIF information included in an iPhone 3GS taken photo

Camera-Specific Properties:

Equipment Make: Apple
Camera Model: iPhone
Camera Software: QuickTime 7.6.3

Image-Specific Properties:

Image Orientation: Top, Left-Hand
Image Orientation: Top, Left-Hand
Horizontal Resolution: 72 dpi
Vertical Resolution: 72 dpi
Image Created: 2010:02:03 13:13:03
Exposure Time: 1/12 sec
F-Number: f/2.8
ISO Speed Rating: 572
Focal Length: 3.85 mm
Comment: {
    AEAverage = 190;
    AELimitsReached = 0;
    AEStable = 1;
    AFStable = 1;
    AFStatus = 3;
    AGC = 1995;
    AWBBGain = 154;
    AWBGGain = 64;
    AWBRGain = 175;
    AWBStable = 1;
    AccelerometerDeltas = "(0.0036 0.0061 0.0133) @ 0.0200";
    ApertureValue = 3;
    BrightnessValue = -0.6822666032417467;
    CurrentFocusPosition = 138;
    ExposureBias = 0;
    ExposureTime = 0.08316987826086956;
    Fnumber = 2.8;
    FocalLength = 3.85;
    FocusBand = "16.13 in [15.00, 17.58]";
    FocusMode = 1;
    FocusPeakSumArray =     (
        35928,
        36463,
        36765,
        37166,
        138984
    );
    FocusScan = "(15,15.52) (43,15.22) (69,13.15) (94,15.01) (117,15.28) (138,15.93) (159,15.57) (179,15.87) (197,15.71) (215,15.79) (232,15.16) (248,15.89) 5.3s ago";
    FocusScoresArray =     (
        1214274,
        1243724,
        1267066,
        1295066,
        9221437
    );
    FocusWindow = "350/300 300x400";
    FullyExposed = 1;
    ISOSpeedRating = 572;
    NoiseReduction = "S:22 C:12 Y:4";
    OneFrameAEMode = 0;
    Orientation = 6;
    OverflowOccurred = 0;
    PreviousFocusBand = "16.20 in [13.55, 16.18]";
    PreviousFocusScan = "(0,13.18) (29,13.93) (56,13.91) (81,12.98) (105,13.10) (127,14.18) (149,14.50) (169,14.02) (188,13.09) (206,13.66) (223,13.80) (239,14.01) (255,13.10) 9.4s ago";
    SNR = 24.19858388928687;
    SensorID = 13904;
    Sharpness = 7;
    ShutterSpeedValue = 3.587795069486017;
    ispDGain = 256;
    sensorDGain = 256;
    "{Exif}" =     {
        ColorSpace = 65535;
        DateTimeDigitized = "2009:07:26 20:36:54";
        DateTimeOriginal = "2009:07:26 20:36:54";
        ExposureTime = 0.08333333333333333;
        FNumber = 2.8;
        FocalLength = 3.85;
        ISOSpeedRatings =         (
            572
        );
        PixelXDimension = 2048;
        PixelYDimension = 1536;
        Sharpness = 0;
    };
    "{TIFF}" =     {
        DateTime = "2009:07:26 20:36:54";
        Make = Apple;
        Model = iPhone;
        XResolution = 72;
        YResolution = 72;
    };
}
Color Space Information: sRGB
Image Width: 2048
Image Height: 1536
Sharpness: Normal
Latitude: N 52� 32.95'
Longitude: W 1� 48.49'
Time (UTC): 20:36:38.09

Not only the date, time and geolocation are included, but also the Accelerometer details, which would suggest the motion status when you were taking the photo ...

To read Exif metadata from command line, try a tool called jhead

jhead dsc_0790.jpg

To remove Exif metadata from command line, use mogrify in the ImageMagick tool package

mogrify -strip dsc_0790.jpg

or

find ./folder_of_images -name '*.jpg' | xargs mogrify -strip