1

I have two folders full of images, folders 1a and 1b, that I took, and in the process of sorting them for backing up, I noticed they are not the same. The dates in Windows Explorer are all wrong, and although I can swear I did no modifications to either of them (folders, and the images inside) I cannot be certain.

At first I thought only the dates have been changed somehow, but while comparing them with diff application, some of the images are binary same and some differ somehow.

Taking Exiftool and comparing EXIF data from two images that differ, here is the results;

3c3
< [System]        Directory                       : 1a
---
> [System]        Directory                       : 1b
5,7c5,7
< [System]        File Modification Date/Time     : 2014:06:07 09:58:43+02:00
< [System]        File Access Date/Time           : 2015:08:24 02:11:23+02:00
< [System]        File Creation Date/Time         : 2014:06:06 22:00:30+02:00
---
> [System]        File Modification Date/Time     : 2014:06:06 22:00:32+02:00
> [System]        File Access Date/Time           : 2015:08:24 02:11:47+02:00
> [System]        File Creation Date/Time         : 2014:06:07 09:56:28+02:00
19,22d18
< [JFIF]          JFIF Version                    : 1.01
< [JFIF]          Resolution Unit                 : None
< [JFIF]          X Resolution                    : 1
< [JFIF]          Y Resolution                    : 1
26d21
< [IFD0]          Orientation                     : Rotate 90 CW
32a28,38
> [IFD0]          Sensitivity Type                : Standard Output Sensitivity
> [IFD0]          Custom Rendered                 : Normal
> [IFD0]          Exposure Mode                   : Auto
> [IFD0]          White Balance                   : Auto
> [IFD0]          Digital Zoom Ratio              : 0
> [IFD0]          Focal Length In 35mm Format     : 27 mm
> [IFD0]          Scene Capture Type              : Standard
> [IFD0]          Gain Control                    : High gain up
> [IFD0]          Contrast                        : Normal
> [IFD0]          Saturation                      : Normal
> [IFD0]          Sharpness                       : Normal
37d42
< [ExifIFD]       Sensitivity Type                : Standard Output Sensitivity
52,53c57,58
< [ExifIFD]       Exif Image Width                : 4608
< [ExifIFD]       Exif Image Height               : 3456
---
> [ExifIFD]       Exif Image Width                : 3456
> [ExifIFD]       Exif Image Height               : 4608
56,65d60
< [ExifIFD]       Custom Rendered                 : Normal
< [ExifIFD]       Exposure Mode                   : Auto
< [ExifIFD]       White Balance                   : Auto
< [ExifIFD]       Digital Zoom Ratio              : 0
< [ExifIFD]       Focal Length In 35mm Format     : 27 mm
< [ExifIFD]       Scene Capture Type              : Standard
< [ExifIFD]       Gain Control                    : High gain up
< [ExifIFD]       Contrast                        : Normal
< [ExifIFD]       Saturation                      : Normal
< [ExifIFD]       Sharpness                       : Normal
74c69
< [Olympus]       Preview Image Start             : 2927433
---
> [Olympus]       Preview Image Start             : 2927265
107,108d101
< [InteropIFD]    Interoperability Index          : R98 - DCF basic file (sRGB)
< [InteropIFD]    Interoperability Version        : 0100
114,115c107,108
< [IFD1]          Thumbnail Offset                : 9234
< [IFD1]          Thumbnail Length                : 6301
---
> [IFD1]          Thumbnail Offset                : 7946
> [IFD1]          Thumbnail Length                : 6251
122c115
< [Composite]     Thumbnail Image                 : (Binary data 6301 bytes, use -b option to extract)
---
> [Composite]     Thumbnail Image                 : (Binary data 6251 bytes, use -b option to extract)

Is there anything inside this results (note: these are only the diff results) that can tell what has been changed / done to them?

My usual toolbox includes: ACDSee 32 2.4 (the very old one, the classic), Windows Explorer and Photo Viewer.

3

The image has been rotated. Image in directory 1a is 4608 px wide, 3456 px high and has an Orientation tag of Rotate 90 CW. So it is a portrait picture that is in landscape orientation. If you look at it with a image viewer that has been told to ignore orientation, it will look like it is turned on it's side. The image in 1b is 3456 px wide and 4608 px high, so it has been rotated.

I would assume that the images in dir 1a would be the originals, since when a camera saves the image, it is in landscape mode and it sets the Orientation tag based on the orientation of the camera, but I would double check to be sure.

It looks like the rest of the data has just been reorganized. Items like Thumbnail Offset and Preview Image Start have been properly changed to reflect the reorganization of the exif data. Thumbnail Length has changed, which seems to me that the Thumbnail has also been rotated or possibly rewritten, though I could be wrong on that. The rest of the Exif data has changed position within the Exif as well, but still fine.

Both ACDSee and Windows Photo Viewer appear to be able to losslessly rotate jpg images, though ACDSee appears to need have a 'force lossless rotation' option set.

  • 1
    This seems very likely. From the question, some images are binary identical and some are unchanged — I bet only the portrait-orientation photos are changed. – mattdm Sep 20 '15 at 15:46
  • Interesting, but if 1a files are not rotated, why is Windows Explorer (in thumbnails mode) showing them rotated? – Rook Sep 20 '15 at 16:06
  • Some quick research online suggests that Windows explorer and Windows Photo Viewer do not honor the orientation tag, but that appears to have changed at some point. My quick test using Windows 8.1, both explorer (using large thumbs) and the Photo Viewer properly orient images based upon the orientation tag. Might I ask what version of Windows you are using? This is the type of stuff I like to keep track of. – StarGeek Sep 20 '15 at 19:23
  • @StarGeek - Windows 7. – Rook Sep 20 '15 at 19:43
  • 1
    Both programs are reading the Exif Orientation tag and rotating the image to the proper orientation for display. You can try this. Make a copy of the file in 1a. Then use this ExifTool command: ExifTool -orientation= FILE replacing FILE with the full path to the copy. Then load the copy into either program. It should now be on its side. – StarGeek Sep 20 '15 at 21:19

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