Keeping EXIF tags
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Photo editors should keep the EXIF tags of your Jpeg image files when you save them after modifications.
But working on photos and keeping the EXIF data is not always as easy as it could be.
That's why I wrote this page to tell you what you can await when you work on photos with different editors.
Which EXIF values will really be kept and which ones may be lost.
In some cases, the behaviour of the photo editors -which EXIF values will be kept-
is different when your work on a photo modifies the width and height (in pixels) or when it does not.
Thus I will report which EXIF values are kept after an image crop (width and height are modified)
and after a brightness/contrast modification (width and height are NOT modified).
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To report which EXIF data will be kept, we will subdivide the tags in 4 categories:
The camera data
The image data
with a special focus on the image width and height that are not always updated when they should.
The EXIF thumbnail
The maker notes
i.e. camera manufacturers specific fields
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Zoner Photo Studio keeps all the EXIF tags.
Crop operation: Zoner Photo Studio keeps the camera EXIF tags and the image EXIF tags.
It updates the width and height EXIF tags that have changed.
It regenerates a new EXIF thumbnail. It keeps the EXIF maker notes
if you select it in the settings dialog.
Brightness modification: Same results as above, but the image size having not been modified,
the width and height EXIF tags are just kept as they were.
The only weird thing I did observe with ZPS is the representation of the EXIF fields X-resolution and Y-resolution.
When I watch these fields with Exifer on an original digital photo of mine, I read 144/1.
After any modification/enhancement of the photo with Zoner Photo Studio, I read 301989888/2097152.
If you do the math, i.e. divide 301989888 by 2097152 the result is 144, so the value is still correct but looks weird.
If you have any idea about the reason of these strange numbers, please contact me.
Zoner Media Explorer keeps most EXIF tags.
Crop operation: ZME, the predecessor of Zoner Photo Studio above,
keeps the camera EXIF tags and the image EXIF tags.
It updates the width and height EXIF tags that have changed.
It regenerates a new EXIF thumbnail. But it loses the EXIF maker notes.
This can eventually be explained by the fact that the maker notes may only be valid for the original photo,
but not for the resulting photo after a manipulation.
Brightness modification: Same results as above, but the image size having not been modified,
the width and height EXIF tags are just kept as they were.
PhotoPhilia keeps the most important EXIF tags.
Crop operation: PhotoPhilia keeps the camera EXIF tags and a large part of the image EXIF tags
(the settings used for the original photo, exposure time, aperture, focal length, etc are kept).
The width and height EXIF tags get lost.
The EXIF thumbnail is lost. The EXIF maker notes are lost.
Brightness modification: Same results as above.
It is regrettable that Photophilia does lose a part of the EXIF tags,
because it is really a friendly and adaptable photo viewer and album, as well as an exceptional batch processor.
I nevertheless use it frequently and recommend it.
Cam2pc keeps either everything or nothing!
Crop operation: Cam2pc loses just all the EXIF tags.
Brightness modification: Cam2pc keeps all the EXIF tags and regenerates the EXIF thumbnail.
Photo-Brush keeps the EXIF tags but with problems.
Crop operation: Photo-Brush keeps the EXIF tags, BUT the EXIF thumbnail has an error and
the width and height EXIF tags that should have been updated, stay unchanged.
Brightness modification: Same results as above, but the size having not been modified,
it is ok that the width and height EXIF tags remain unchanged.
Repairing EXIF tags
Now the good news are that EXIF tags can be repaired. Most problems reported above,
-like lost or bad thumbnails, width and height EXIF tags that are not updated-
can be circumvented by Zoner Photo Studio's
EXIF backup and restore function
or corrected by its
fix bad EXIF marker positions
function and
generate EXIF preview (thumbnail) function.
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Remember, it is highly advisable to always keep your untouched original photo either on your hard disk drive,
as a backup on a CD-rom or better at both places. Always work on a copy to crop, resize, retouch the brightness or whatever!
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Example List of EXIF tags:
| Camera | |
| Description | OLYMPUS DIGITAL CAMERA |
| Make | OLYMPUS OPTICAL CO.,LTD |
| Model | C2500L |
| Orientation (start point) | Upper Left |
| X Resolution | 144 |
| Y Resolution | 144 |
| Resolution Unit | Inch |
| Firmware Version | 09-0117 |
| Date/Time Modified | 2004:02:02 13:49:09 |
| YCbCr Positioning | Datum Point |
| Image | |
| Exposure Time (sec) | 1/400 |
| Aperture | F6.0 |
| Exposure Program | Manual |
| ISO Speed | 100 |
| EXIF Version | 210 |
| Date/Time Taken | 2004:02:02 13:49:09 |
| Date/Time Digitized | 2004:02:02 13:49:09 |
| Components Configuration | 1020300 |
| Exposure Bias (EV) | 0 |
| Max Aperture | 2.6 |
| Metering Mode | Spot |
| Flash | Not Fired |
| Focal Length (mm) | 12.9 |
| User Comment | |
| Copyright | |
| FlashPix Version | 100 |
| Colour Space | sRGB |
| Image Width | 1368 |
| Image Height | 1712 |
| File Source | Digital Still Camera |
| Thumbnail | |
| Thumb Compression | JPEG Compression |
| Thumb X Resolution | 72 |
| Thumb Y Resolution | 72 |
| Thumb Resolution Unit | Inch |
| Thumb Jpeg IF Offset | 3328 |
| Thumb Jpeg IF Byte Count | 8862 |
| Maker Note | |
| Special Mode | Normal, 0, 0 |
| JPEG Quality | HQ |
| Macro | Normal |
| Digital Zoom | 0 |
| Software Release | D4809 |
| Camera Id | OLYMPUS DIGITAL CAMERA |
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If you are a hobby photographer who likes to keep track of values like aperture, exposure time, focal length, etc...
you will appreciate the benefit of software that keeps the EXIF tags.
I recommend you to read the following related pages:
the
EXIF editor page about software with EXIF editing abilities and
the
EXIF viewer page about software with EXIF viewing abilities.
