While my old iPad mini photos say their color space is sRGB, my new iPhone 8 photos tell me their color space is "65535" ("unknown value"). Some sources say this value means "uncalibrated", but that information is of no help. Is there a better source which tells me the true color space of the photos? I want to embed them in a PDF file and for this specify the correct color space.
$ exif IMG_8995.JPG
EXIF tags in 'IMG_8995.JPG' ('Motorola' byte order):
--------------------+----------------------------------------------------------
Tag |Value
--------------------+----------------------------------------------------------
Manufacturer |Apple
Model |iPhone 8
Orientation |Top-left
X-Resolution |72
Y-Resolution |72
Resolution Unit |Inch
Software |11.3.1
Date and Time |2018:05:12 07:58:51
YCbCr Positioning |Centered
Compression |JPEG compression
X-Resolution |72
Y-Resolution |72
Resolution Unit |Inch
Exposure Time |1/2404 sec.
F-Number |f/1,8
Exposure Program |Normal program
ISO Speed Ratings |20
Exif Version |Exif Version 2.21
Date and Time (Origi|2018:05:12 07:58:51
Date and Time (Digit|2018:05:12 07:58:51
Components Configura|Y Cb Cr -
Shutter Speed |11,23 EV (1/2403 sec.)
Aperture |1,70 EV (f/1,8)
Brightness |10,62 EV (5394,70 cd/m^2)
Exposure Bias |0,00 EV
Metering Mode |Spot
Flash |Flash did not fire, compulsory flash mode
Focal Length |4,0 mm
Subject Area |Within rectangle (width 753, height 756) around (x,y) = (3
Maker Note |926 bytes undefined data
Sub-second Time (Ori|700
Sub-second Time (Dig|700
FlashPixVersion |FlashPix Version 1.0
Color Space |Internal error (unknown value 65535)
Pixel X Dimension |4032
Pixel Y Dimension |3024
Sensing Method |One-chip color area sensor
Scene Type |Directly photographed
Exposure Mode |Auto exposure
White Balance |Auto white balance
Focal Length in 35mm|28
Scene Capture Type |Standard
North or South Latit|N
Latitude |47, 43, 40,97
East or West Longitu|E
Longitude |13, 12, 25,38
Altitude Reference |Sea level
Altitude |989,768
GPS Time (Atomic Clo|05:58:51,00
Speed Unit |K
Speed of GPS Receive|0,03549
GPS Image Direction |T
GPS Image Direction |221,05
Reference for Bearin|T
Bearing of Destinati|221,05
GPS Date |2018:05:12
--------------------+----------------------------------------------------------
EXIF data contains a thumbnail (9560 bytes).
[UPDATE] Now, using exiftool (as suggested by mattdm):
$ exiftool IMG_8995.JPG
ExifTool Version Number : 10.60
File Name : IMG_8995.JPG
Directory : .
File Size : 3.8 MB
File Modification Date/Time : 2018:05:12 17:54:37+02:00
File Access Date/Time : 2018:05:17 21:55:15+02:00
File Inode Change Date/Time : 2018:05:12 17:54:37+02:00
File Permissions : rw-r--r--
File Type : JPEG
File Type Extension : jpg
MIME Type : image/jpeg
Exif Byte Order : Big-endian (Motorola, MM)
Make : Apple
Camera Model Name : iPhone 8
Orientation : Horizontal (normal)
X Resolution : 72
Y Resolution : 72
Resolution Unit : inches
Software : 11.3.1
Modify Date : 2018:05:12 07:58:51
Y Cb Cr Positioning : Centered
Exposure Time : 1/2404
F Number : 1.8
Exposure Program : Program AE
ISO : 20
Exif Version : 0221
Date/Time Original : 2018:05:12 07:58:51
Create Date : 2018:05:12 07:58:51
Components Configuration : Y, Cb, Cr, -
Shutter Speed Value : 1/2404
Aperture Value : 1.8
Brightness Value : 10.62069397
Exposure Compensation : 0
Metering Mode : Spot
Flash : Off, Did not fire
Focal Length : 4.0 mm
Subject Area : 3194 1215 753 756
Run Time Flags : Valid
Run Time Value : 95831447299500
Run Time Scale : 1000000000
Run Time Epoch : 0
Acceleration Vector : -0.9967756794 0.02542742023 -0.03952735125
Sub Sec Time Original : 700
Sub Sec Time Digitized : 700
Flashpix Version : 0100
Color Space : Uncalibrated
Exif Image Width : 4032
Exif Image Height : 3024
Sensing Method : One-chip color area
Scene Type : Directly photographed
Exposure Mode : Auto
White Balance : Auto
Focal Length In 35mm Format : 28 mm
Scene Capture Type : Standard
Lens Info : 3.99mm f/1.8
Lens Make : Apple
Lens Model : iPhone 8 back camera 3.99mm f/1.8
GPS Latitude Ref : North
GPS Longitude Ref : East
GPS Altitude Ref : Above Sea Level
GPS Time Stamp : 05:58:51
GPS Speed Ref : km/h
GPS Speed : 0.03548649749
GPS Img Direction Ref : True North
GPS Img Direction : 221.0531915
GPS Dest Bearing Ref : True North
GPS Dest Bearing : 221.0531915
GPS Date Stamp : 2018:05:12
GPS Horizontal Positioning Error: 4 m
Compression : JPEG (old-style)
Thumbnail Offset : 2114
Thumbnail Length : 9560
Profile CMM Type : appl
Profile Version : 4.0.0
Profile Class : Display Device Profile
Color Space Data : RGB
Profile Connection Space : XYZ
Profile Date Time : 2017:07:07 13:22:32
Profile File Signature : acsp
Primary Platform : Apple Computer Inc.
CMM Flags : Not Embedded, Independent
Device Manufacturer : APPL
Device Model :
Device Attributes : Reflective, Glossy, Positive, Color
Rendering Intent : Perceptual
Connection Space Illuminant : 0.9642 1 0.82491
Profile Creator : appl
Profile ID : ca1a9582257f104d389913d5d1ea1582
Profile Description : Display P3
Profile Copyright : Copyright Apple Inc., 2017
Media White Point : 0.95045 1 1.08905
Red Matrix Column : 0.51512 0.2412 -0.00105
Green Matrix Column : 0.29198 0.69225 0.04189
Blue Matrix Column : 0.1571 0.06657 0.78407
Red Tone Reproduction Curve : (Binary data 32 bytes, use -b option to extract)
Chromatic Adaptation : 1.04788 0.02292 -0.0502 0.02959 0.99048 -0.01706 -0.00923 0.01508 0.75168
Blue Tone Reproduction Curve : (Binary data 32 bytes, use -b option to extract)
Green Tone Reproduction Curve : (Binary data 32 bytes, use -b option to extract)
Image Width : 4032
Image Height : 3024
Encoding Process : Baseline DCT, Huffman coding
Bits Per Sample : 8
Color Components : 3
Y Cb Cr Sub Sampling : YCbCr4:2:0 (2 2)
Aperture : 1.8
GPS Altitude : 989.7 m Above Sea Level
GPS Date/Time : 2018:05:12 05:58:51Z
GPS Latitude : 47 deg 43' 40.97" N
GPS Longitude : 13 deg 12' 25.38" E
GPS Position : 47 deg 43' 40.97" N, 13 deg 12' 25.38" E
Image Size : 4032x3024
Megapixels : 12.2
Run Time Since Power Up : 1 days 2:37:11
Scale Factor To 35 mm Equivalent: 7.0
Shutter Speed : 1/2404
Create Date : 2018:05:12 07:58:51.700
Date/Time Original : 2018:05:12 07:58:51.700
Thumbnail Image : (Binary data 9560 bytes, use -b option to extract)
Circle Of Confusion : 0.004 mm
Field Of View : 65.5 deg
Focal Length : 4.0 mm (35 mm equivalent: 28.0 mm)
Hyperfocal Distance : 2.07 m
Light Value : 15.2
Answer
For whatever reason, the ColorSpace tag is not very useful in EXIF. The only standard values are 1 (sRGB) and 65535 ("uncalibrated"). All other values are reserved. Some cameras use them to mean Adobe RGB or something else, but this is non-standard. Apple is, in fact, using Something Else, and that's found elsewhere in the metadata. With ExifTool, looking for tags starting with Profile, I found:
Profile CMM Type : Apple Computer Inc.
Profile Version : 4.0.0
Profile Class : Display Device Profile
Profile Connection Space : XYZ
Profile Date Time : 2017:07:07 13:22:32
Profile File Signature : acsp
Profile Creator : Apple Computer Inc.
Profile ID : ca1a9582257f104d389913d5d1ea1582
Profile Description : Display P3
Profile Copyright : Copyright Apple Inc., 2017
which leads us to Apple Core Graphics documentation which says:
displayP3
The name of the Display P3 color space, created by Apple Inc. This color space uses the DCI P3 primaries, a D65 white point, and the same gamma curve as the sRGB color space.
You can read more about the DCI-P3 colorspace on Wikipedia.
No comments:
Post a Comment