I am attempting to extract a JPEG thumbnail image from a CR2 image, using exiftool, in Windows.
I was successful in doing so using this program, QuickJPGFromCR2. From the description, it appears to extract the JPEG preview from the EXIF data. The resulting file is the same width and height as the original image and is between 1~2 MB for the files that I am working with.
Firstly, the output of exiftool .\Kendall_FACS_0002_0100A.cr2 is as follows:
ExifTool Version Number : 10.45
File Name : Kendall_FACS_0002_0100A.cr2
Directory : .
File Size : 25 MB
File Modification Date/Time : 2016:10:20 14:47:47-05:00
File Access Date/Time : 2016:11:21 18:26:10-06:00
File Creation Date/Time : 2017:01:23 14:14:05-06:00
File Permissions : rw-rw-rw-
File Type : CR2
File Type Extension : cr2
MIME Type : image/x-canon-cr2
Exif Byte Order : Little-endian (Intel, II)
Image Width : 5184
Image Height : 3456
Bits Per Sample : 8 8 8
Compression : JPEG (old-style)
Make : Canon
Camera Model Name : Canon EOS REBEL T3i
Preview Image Start : 68120
Orientation : Horizontal (normal)
Preview Image Length : 1708300
X Resolution : 72
Y Resolution : 72
Resolution Unit : inches
Modify Date : 2016:10:20 14:46:19
Artist :
Rating : 0
Copyright :
Exposure Time : 1/100
F Number : 16.0
Exposure Program : Manual
ISO : 100
Sensitivity Type : Recommended Exposure Index
Recommended Exposure Index : 100
Exif Version : 0230
Date/Time Original : 2016:10:20 14:46:19
Create Date : 2016:10:20 14:46:19
Components Configuration : Y, Cb, Cr, -
Shutter Speed Value : 1/99
Aperture Value : 16.0
Flash : Off, Did not fire
Focal Length : 40.0 mm
Macro Mode : Normal
Self Timer : Off
Quality : RAW
Canon Flash Mode : Off
Continuous Drive : Single
Focus Mode : Manual Focus (3)
Record Mode : CR2
Canon Image Size : n/a
Easy Mode : Manual
Digital Zoom : None
Contrast : Normal
Saturation : Normal
Metering Mode : Evaluative
Focus Range : Not Known
Canon Exposure Mode : Manual
Lens Type : Canon EF 40mm f/2.8 STM
Max Focal Length : 40 mm
Min Focal Length : 40 mm
Focal Units : 1/mm
Max Aperture : 2.8
Min Aperture : 23
Flash Activity : 0
Flash Bits : (none)
Zoom Source Width : 0
Zoom Target Width : 0
Manual Flash Output : n/a
Color Tone : Normal
SRAW Quality : n/a
Auto ISO : 100
Base ISO : 100
Measured EV : 6.00
Target Aperture : 16
Target Exposure Time : 1/102
Exposure Compensation : 0
White Balance : Daylight
Slow Shutter : None
Shot Number In Continuous Burst : 0
Optical Zoom Code : n/a
Camera Temperature : 30 C
Flash Guide Number : 0
Flash Exposure Compensation : 0
Auto Exposure Bracketing : Off
AEB Bracket Value : 0
Control Mode : Camera Local Control
Measured EV 2 : 6.625
Bulb Duration : 0
Camera Type : EOS High-end
ND Filter : n/a
Canon Image Type : Canon EOS REBEL T3i
Canon Firmware Version : Firmware Version 1.0.2
Flash Metering Mode : Off
Camera Orientation : Horizontal (normal)
Firmware Version : 1.0.2
File Index : 2
Directory Index : 100
Contrast Standard : 0
Sharpness Standard : 3
Saturation Standard : 0
Color Tone Standard : 0
Contrast Portrait : 0
Sharpness Portrait : 2
Saturation Portrait : 0
Color Tone Portrait : 0
Contrast Landscape : 0
Sharpness Landscape : 4
Saturation Landscape : 0
Color Tone Landscape : 0
Contrast Neutral : 0
Sharpness Neutral : 0
Saturation Neutral : 0
Color Tone Neutral : 0
Contrast Faithful : 0
Sharpness Faithful : 0
Saturation Faithful : 0
Color Tone Faithful : 0
Contrast Monochrome : 0
Sharpness Monochrome : 3
Filter Effect Monochrome : None
Toning Effect Monochrome : None
Contrast Auto : 0
Sharpness Auto : 3
Saturation Auto : 0
Color Tone Auto : 0
Filter Effect Auto : n/a
Toning Effect Auto : n/a
Contrast User Def 1 : 0
Sharpness User Def 1 : 3
Saturation User Def 1 : 0
Color Tone User Def 1 : 0
Filter Effect User Def 1 : None
Toning Effect User Def 1 : None
Contrast User Def 2 : 0
Sharpness User Def 2 : 3
Saturation User Def 2 : 0
Color Tone User Def 2 : 0
Filter Effect User Def 2 : None
Toning Effect User Def 2 : None
Contrast User Def 3 : 0
Sharpness User Def 3 : 3
Saturation User Def 3 : 0
Color Tone User Def 3 : 0
Filter Effect User Def 3 : None
Toning Effect User Def 3 : None
User Def 1 Picture Style : Auto
User Def 2 Picture Style : Auto
User Def 3 Picture Style : Auto
Canon Model ID : EOS Rebel T3i / 600D / Kiss X5
Thumbnail Image Valid Area : 0 159 7 112
AF Area Mode : Off (Manual Focus)
Num AF Points : 9
Valid AF Points : 9
Canon Image Width : 5184
Canon Image Height : 3456
AF Image Width : 5184
AF Image Height : 3456
AF Area Widths : 139 139 139 196 238 196 139 139 139
AF Area Heights : 186 186 186 127 231 127 186 186 186
AF Area X Positions : -1477 -886 -886 0 0 0 886 886 1477
AF Area Y Positions : 0 418 -418 787 0 -787 418 -418 0
AF Points In Focus : (none)
AF Points Selected : 0,1,2,3,4,5,6,7,8
Original Decision Data Offset : 0
Bracket Mode : Off
Bracket Value : 0
Bracket Shot Number : 0
Raw Jpg Size : Large
Long Exposure Noise Reduction 2 : Off
WB Bracket Mode : Off
WB Bracket Value AB : 0
WB Bracket Value GM : 0
Live View Shooting : Off
Focus Distance Upper : 2.16 m
Focus Distance Lower : 1.46 m
Flash Exposure Lock : Off
Internal Serial Number : ZC1954285
Dust Removal Data : (Binary data 1024 bytes, use -b option to extract)
Crop Left Margin : 0
Crop Right Margin : 0
Crop Top Margin : 0
Crop Bottom Margin : 0
Exposure Level Increments : 1/3 Stop
ISO Expansion : Off
Flash Sync Speed Av : Auto
Long Exposure Noise Reduction : Off
High ISO Noise Reduction : Standard
Highlight Tone Priority : Disable
AF Assist Beam : Does not emit
Mirror Lockup : Enable
Shutter-AE Lock : AF/AE lock
Set Button When Shooting : Normal (disabled)
LCD Display At Power On : Display
Add Original Decision Data : Off
Aspect Ratio : 3:2
Cropped Image Width : 5184
Cropped Image Height : 3456
Cropped Image Left : 0
Cropped Image Top : 0
Tone Curve : Standard
Sharpness : 3
Sharpness Frequency : n/a
Sensor Red Level : 0
Sensor Blue Level : 0
White Balance Red : 0
White Balance Blue : 0
Color Temperature : 5200
Picture Style : Auto
Digital Gain : 0
WB Shift AB : 0
WB Shift GM : 0
Measured RGGB : 431 1024 1024 768
VRD Offset : 0
Sensor Width : 5344
Sensor Height : 3516
Sensor Left Border : 152
Sensor Top Border : 56
Sensor Right Border : 5335
Sensor Bottom Border : 3511
Black Mask Left Border : 0
Black Mask Top Border : 0
Black Mask Right Border : 0
Black Mask Bottom Border : 0
Color Data Version : 10 (600D/1200D)
WB RGGB Levels As Shot : 2123 1024 1024 1556
Color Temp As Shot : 5200
WB RGGB Levels Auto : 2028 1024 1024 1606
Color Temp Auto : 4908
WB RGGB Levels Measured : 2028 1024 1024 1606
Color Temp Measured : 4908
WB RGGB Levels Daylight : 2123 1024 1024 1556
Color Temp Daylight : 5200
WB RGGB Levels Shade : 2439 1024 1024 1321
Color Temp Shade : 7000
WB RGGB Levels Cloudy : 2280 1024 1024 1431
Color Temp Cloudy : 6000
WB RGGB Levels Tungsten : 1540 1024 1024 2341
Color Temp Tungsten : 3200
WB RGGB Levels Fluorescent : 1869 1024 1024 2226
Color Temp Fluorescent : 3729
WB RGGB Levels Kelvin : 2123 1024 1024 1556
Color Temp Kelvin : 5200
WB RGGB Levels Flash : 2367 1024 1024 1411
Color Temp Flash : 6303
Average Black Level : 2048 2048 2048 2048
Raw Measured RGGB : 99047 229396 224807 170653
Per Channel Black Level : 2047 2047 2048 2048
Normal White Level : 11767
Specular White Level : 12279
Linearity Upper Margin : 10000
Picture Style User Def : Auto; Auto; Auto
Picture Style PC : None; None; None
Custom Picture Style File Name :
Vignetting Corr Version : 0
Peripheral Lighting : Off
Chromatic Aberration Corr : Off
Peripheral Lighting Value : 0
Original Image Width : 5184
Original Image Height : 3456
Peripheral Lighting Setting : Off
Peripheral Illumination Corr : Off
Auto Lighting Optimizer : Off
User Comment :
Sub Sec Time : 46
Sub Sec Time Original : 46
Sub Sec Time Digitized : 46
Flashpix Version : 0100
Color Space : sRGB
Exif Image Width : 5184
Exif Image Height : 3456
Interoperability Index : R98 - DCF basic file (sRGB)
Interoperability Version : 0100
Focal Plane X Resolution : 5728.176796
Focal Plane Y Resolution : 5808.403361
Focal Plane Resolution Unit : inches
Custom Rendered : Normal
Exposure Mode : Manual
Scene Capture Type : Standard
Owner Name : CAM1100A1
Serial Number : 252076117630
Lens Info : 40mm f/?
Lens Model : EF40mm f/2.8 STM
Lens Serial Number : 00002bc0be
Thumbnail Offset : 55048
Thumbnail Length : 13072
Photometric Interpretation : RGB
Samples Per Pixel : 3
Rows Per Strip : 432
Planar Configuration : Chunky
Strip Offsets : 3513124
Strip Byte Counts : 22248252
Raw Image Segmentation : 2 1728 1888
SRaw Type : 1
Aperture : 16.0
Drive Mode : Single-frame Shooting
File Number : 100-0002
Image Size : 5184x3456
Lens : 40.0 mm
Lens ID : Canon EF 40mm f/2.8 STM
Megapixels : 17.9
Preview Image : (Binary data 1708300 bytes, use -b option to extract)
Scale Factor To 35 mm Equivalent: 1.6
Shooting Mode : Manual
Shutter Speed : 1/100
Create Date : 2016:10:20 14:46:19.46
Date/Time Original : 2016:10:20 14:46:19.46
Modify Date : 2016:10:20 14:46:19.46
Thumbnail Image : (Binary data 13072 bytes, use -b option to extract)
WB RGGB Levels : 2123 1024 1024 1556
Blue Balance : 1.519531
Circle Of Confusion : 0.019 mm
Depth Of Field : 1.38 m (1.35 - 2.73 m)
Field Of View : 31.9 deg
Focal Length : 40.0 mm (35 mm equivalent: 62.9 mm)
Hyperfocal Distance : 5.23 m
Lens : 40.0 mm (35 mm equivalent: 62.9 mm)
Light Value : 14.6
Red Balance : 2.073242
So, looking at the binary data fields (those that suggest extracting using the -b option), we get:
Dust Removal Data : (Binary data 1024 bytes, use -b option to extract)
Preview Image : (Binary data 1708300 bytes, use -b option to extract)
Thumbnail Image : (Binary data 13072 bytes, use -b option to extract)
The Preview Image tag seems to be what we are looking for, however the Thumbnail Image is intriguing as well (although quite small).
Running the following commands:
exiftool -b .\Kendall_FACS_0002_0100A.cr2 > out.jpg
exiftool -b -PreviewImage .\Kendall_FACS_0002_0100A.cr2 > out.jpg
exiftool -b -ThumbnailImage .\Kendall_FACS_0002_0100A.cr2 > out.jpg
The first two commands result in files 3.28 MB large, while the last is only 25.6KB. All fail to open in any program. Windows Photo Viewer says that it can't open the file because, the file appears to be damaged, corrputed, or is too large.
Using ImageMagick's identify command gives the following output for the Preview Image tag:
exiftool -b -PreviewImage .\Kendall_FACS_0002_0100A.cr2 | identify -
identify.exe: no decode delegate for this image format `' @ error/constitute.c/ReadImage/504.
exiftool -b -PreviewImage .\Kendall_FACS_0002_0100A.cr2 | identify jpg:-
identify.exe: Not a JPEG file: starts with 0x3f 0x3f `-' @ error/jpeg.c/JPEGErrorHandler/322.
I've noticed elsewhere on the internet people using the -JpegFromRaw option, but my EXIF data has no such tag.
So, what the heck am I doing wrong?
