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Merged
merged 1 commit into from
Oct 19, 2022
Merged

exif: ensure prefix is present before parsing #3100

merged 1 commit into from
Oct 19, 2022

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lovell
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@lovell lovell commented Oct 19, 2022

It looks like some newer Apple devices are attaching EXIF to images without the Exif\0\0 prefix, however libexif still requires it due to JPEG/JFIF/APP1 marker heritage.

There's an upstream issue about this at libexif/libexif#58

Originally reported at lovell/sharp#3412

Before:

exif-data: 2402 bytes of binary data
exif-ifd0-XResolution: 72009/1000 (72.009, Rational, 1 components, 8 bytes)
exif-ifd0-YResolution: 72009/1000 (72.009, Rational, 1 components, 8 bytes)
exif-ifd0-ResolutionUnit: 2 (Inch, Short, 1 components, 2 bytes)
exif-ifd2-ExifVersion: Exif Version 2.1 (Exif Version 2.1, Undefined, 4 components, 4 bytes)
exif-ifd2-FlashpixVersion: FlashPix Version 1.0 (FlashPix Version 1.0, Undefined, 4 components, 4 bytes)
exif-ifd2-ColorSpace: 65535 (Uncalibrated, Short, 1 components, 2 bytes)

After:

exif-data: 2402 bytes of binary data
exif-ifd0-Make: Apple (Apple, ASCII, 6 components, 6 bytes)
exif-ifd0-Model: iPhone 11 Pro Max (iPhone 11 Pro Max, ASCII, 18 components, 18 bytes)
exif-ifd0-Orientation: 1 (Top-left, Short, 1 components, 2 bytes)
exif-ifd0-XResolution: 72/1 (72, Rational, 1 components, 8 bytes)
exif-ifd0-YResolution: 72/1 (72, Rational, 1 components, 8 bytes)
exif-ifd0-ResolutionUnit: 2 (Inch, Short, 1 components, 2 bytes)
exif-ifd0-Software: 15.5 (15.5, ASCII, 5 components, 5 bytes)
exif-ifd0-DateTime: 2022:07:08 13:00:46 (2022:07:08 13:00:46, ASCII, 20 components, 20 bytes)
exif-ifd2-ExposureTime: 1/122 (1/122 sec., Rational, 1 components, 8 bytes)
exif-ifd2-FNumber: 12/5 (f/2.4, Rational, 1 components, 8 bytes)
exif-ifd2-ExposureProgram: 2 (Normal programme, Short, 1 components, 2 bytes)
exif-ifd2-ISOSpeedRatings: 25 (25, Short, 1 components, 2 bytes)
exif-ifd2-ExifVersion: Exif Version 2.32 (Exif Version 2.32, Undefined, 4 components, 4 bytes)
exif-ifd2-DateTimeOriginal: 2022:07:08 13:00:46 (2022:07:08 13:00:46, ASCII, 20 components, 20 bytes)
exif-ifd2-DateTimeDigitized: 2022:07:08 13:00:46 (2022:07:08 13:00:46, ASCII, 20 components, 20 bytes)
exif-ifd2-OffsetTime: +01:00 (+01:00, ASCII, 7 components, 7 bytes)
exif-ifd2-OffsetTimeOriginal: +01:00 (+01:00, ASCII, 7 components, 7 bytes)
exif-ifd2-OffsetTimeDigitized: +01:00 (+01:00, ASCII, 7 components, 7 bytes)
exif-ifd2-ComponentsConfiguration: Y Cb Cr - (Y Cb Cr -, Undefined, 4 components, 4 bytes)
exif-ifd2-ShutterSpeedValue: 68321/9857 (6.93 EV (1/122 sec.), SRational, 1 components, 8 bytes)
exif-ifd2-ApertureValue: 4845/1918 (2.53 EV (f/2.4), Rational, 1 components, 8 bytes)
exif-ifd2-BrightnessValue: 35212/4987 (7.06 EV (457.43 cd/m^2), SRational, 1 components, 8 bytes)
exif-ifd2-ExposureBiasValue: 0/1 (0.00 EV, SRational, 1 components, 8 bytes)
exif-ifd2-MeteringMode: 5 (Pattern, Short, 1 components, 2 bytes)
exif-ifd2-Flash: 16 (Flash did not fire, compulsory flash mode, Short, 1 components, 2 bytes)
exif-ifd2-FocalLength: 77/50 (1.5 mm, Rational, 1 components, 8 bytes)
exif-ifd2-SubjectArea: 2015 1511 2324 1392 (Within rectangle (width 2324, height 1392) around (x,y) = (2015,1511), Short, 4 components, 8 bytes)
exif-ifd2-MakerNote: 1236 bytes undefined data (1236 bytes undefined data, Undefined, 1236 components, 1236 bytes)
exif-ifd2-SubsecTime: 520 (520, ASCII, 4 components, 4 bytes)
exif-ifd2-SubSecTimeOriginal: 520 (520, ASCII, 4 components, 4 bytes)
exif-ifd2-SubSecTimeDigitized: 520 (520, ASCII, 4 components, 4 bytes)
exif-ifd2-FlashpixVersion: FlashPix Version 1.0 (FlashPix Version 1.0, Undefined, 4 components, 4 bytes)
exif-ifd2-ColorSpace: 1 (sRGB, Short, 1 components, 2 bytes)
exif-ifd2-PixelXDimension: 288 (288, Long, 1 components, 4 bytes)
exif-ifd2-PixelYDimension: 279 (279, Long, 1 components, 4 bytes)
exif-ifd2-SensingMethod: 2 (One-chip colour area sensor, Short, 1 components, 2 bytes)
exif-ifd2-SceneType: Directly photographed (Directly photographed, Undefined, 1 components, 1 bytes)
exif-ifd2-ExposureMode: 0 (Auto exposure, Short, 1 components, 2 bytes)
exif-ifd2-WhiteBalance: 0 (Auto white balance, Short, 1 components, 2 bytes)
exif-ifd2-DigitalZoomRatio: 1512/1325 (1.1411, Rational, 1 components, 8 bytes)
exif-ifd2-FocalLengthIn35mmFilm: 15 (15, Short, 1 components, 2 bytes)
exif-ifd2-SceneCaptureType: 0 (Standard, Short, 1 components, 2 bytes)
exif-ifd2-LensSpecification: 807365/524263 6/1 9/5 12/5 (1.540000,  6, 1.8, 2.4, Rational, 4 components, 32 bytes)
exif-ifd2-LensMake: Apple (Apple, ASCII, 6 components, 6 bytes)
exif-ifd2-LensModel: iPhone 11 Pro Max back triple camera 1.54mm f/2.4 (iPhone 11 Pro Max back triple camera 1.54mm f/2.4, ASCII, 50 components, 50 bytes)
exif-ifd2-CompositeImage: 2 (2, Short, 1 components, 2 bytes)
exif-ifd3-GPSLatitudeRef: N (N, ASCII, 2 components, 2 bytes)
exif-ifd3-GPSLatitude: 55/1 14/1 2461/100 (55, 14, 24.61, Rational, 3 components, 24 bytes)
exif-ifd3-GPSLongitudeRef: W (W, ASCII, 2 components, 2 bytes)
exif-ifd3-GPSLongitude: 6/1 30/1 3820/100 ( 6, 30, 38.20, Rational, 3 components, 24 bytes)
exif-ifd3-GPSAltitudeRef: Sea level (Sea level, Byte, 1 components, 1 bytes)
exif-ifd3-GPSAltitude: 52037/8161 (6.3763, Rational, 1 components, 8 bytes)
exif-ifd3-GPSSpeedRef: K (K, ASCII, 2 components, 2 bytes)
exif-ifd3-GPSSpeed: 0/1 ( 0, Rational, 1 components, 8 bytes)
exif-ifd3-GPSImgDirectionRef: T (T, ASCII, 2 components, 2 bytes)
exif-ifd3-GPSImgDirection: 130663/487 (268.302, Rational, 1 components, 8 bytes)
exif-ifd3-GPSDestBearingRef: T (T, ASCII, 2 components, 2 bytes)
exif-ifd3-GPSDestBearing: 130663/487 (268.302, Rational, 1 components, 8 bytes)
exif-ifd3-GPSHPositioningError: 7566/1549 (4.8844, Rational, 1 components, 8 bytes)

@lovell
exif: ensure prefix is present before parsing
1a60c7c 
Newer Apple devices are creating EXIF without this however libexif
still requires it due to JPEG/JFIF/APP1 marker heritage.
@lovell lovell mentioned this pull request Oct 19, 2022
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@jcupitt jcupitt merged commit 1fc01c0 into libvips:8.13 Oct 19, 2022
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jcupitt commented Oct 19, 2022

Nice! I merged to master as well.

@lovell lovell deleted the exif-ensure-prefix branch October 19, 2022 12:10
@lovell lovell mentioned this pull request Oct 22, 2022
Merged
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@lovell @jcupitt