Removing EXIF metadata with ExifTool

12Apr08

About two weeks back, I wrote an entry about using ExifTool to easily view metadata in your images. Beyond just viewing metadata, ExifTool can also change or remove them. This entry is about removal.

Now, why would you want to remove anything from the EXIF?

I normally shoot with a Nikon D200 in raw capture mode, and import all my photos into Adobe Lightroom. Most times I would at least make adjustments to my photos, such as white balance, highlight recovery, fill light, clarify, vibrance, etc. Other times, when needed, I’ll modify saturation, desaturate them to make them into B&W images, add vignetting for effect, etc. As it turns out, when I export my photos from Lightroom, it also exports all of my settings into the EXIF of the photos.

For example, in the photo below, after exporting from Lightroom, the following EXIF data is written to the image:

Temperature : 4800
Tint : -5
Exposure : 0.00
Shadows : 5
Brightness : +50
Contrast : +27
Saturation : 0
Sharpness : 71
Luminance Smoothing : 0
Color Noise Reduction : 25
Chromatic Aberration R : 0
Chromatic Aberration B : 0
Vignette Amount : -26
Vignette Midpoint : 50
Shadow Tint : 0
Red Hue : -9
Red Saturation : 0
Green Hue : -3
Green Saturation : 0
Blue Hue : -15
Blue Saturation : 0
Fill Light : 24
Vibrance : +19
Highlight Recovery : 13
Clarity : 63

Donkeys asking for apples

That’s just a small sample of what is exported. Sometimes this is fine — I may want whoever is looking at them to know how I got to the end result, sometimes I’d rather not share the info, and that’s where ExifTool comes into the picture (no pun intended).

If you know what fields in the EXIF you wish to remove, you can simply execute ExifTool at the command prompt with the following command:

<path to>\ExifTool(-k).exe -<field 1 to remove>=
-<field 2 to remove>= ... <image filename>

So if I want to remove Sharpness and Shadow Tint, I’ll need to run:

<path to>\ExifTool(-k).exe -Sharpness= -ShadowTint= <image filename>

That’s it. Notice that the spaces in the field names are removed when you execute ExifTool.

To make life easier, and that’s always one of my goals, I’ve written up a simple batch file to handle the removal of a bunch of fields that are written out by Lightroom. You can get the batch file here.

What you’ll need to do is the following:

1. Download the CleanUpEXIF.bat batch file
   Ideally, you’ll probably want to save it in the same directory as where you installed ExifTool
2. Edit the first line of the batch file to point to the installation location of your ExifTool
   Basically, you’ll need to replace the “<path to>” in the first line with the correct path
3. For ease of use, you might want to create a link of the batch file to your desktop
4. Now all you’ll need to do to remove the metadata fields from your images is to drag your images onto the link on your desktop and Bob’s your uncle

What will happen when you modify the metadata is that ExifTool will copy the original file into another file with an extra extension of “.orig” and adds “_original” to the end of the filename, and remove the metadata from the actual file.

14 Apr 2008 Update: Add “-overwrite_original” to the ExifTool switches if you don’t need this safety net

In the batch file, you’ll see lines such as:

-Software= ^
-ModifyDate= ^
-CreatorTool= ^
-MetadataDate= ^

Each line is a field to remove. The caret (“^”) at the end of each line is a continuation character to tell Windows that the command line hasn’t ended yet. To add other fields to remove, just code in the fields into the batch file with the same format.

So why didn’t I make it even easier and have this as an option through the right-click context, like I originally did with ExifTool? Well, the problem is with Windows filename length handling. If you try to do this with the right-click context, the filename passed to ExifTool is the shortened 8.3 version, rather than the original name. When it modfies the file and writes out the name, it uses the shortened 8.3 version, which really isn’t what I want. So if your original filename is “20080403_HohRainForest_1398.jpg”, instead of passing the full filename to ExifTool for renaming, MS Windows passes the shortened 8.3 version or “200804~1.jpg”. This means your modified images no longer have the same names as your actual file.

If someone has a way around this, I’m all ears.

Filed under: Photography   |  3 Comments
Tags: EXIF, metadata, software