My “Metadata Wrangler” plugin filter for Lightroom 2 or later allows you to strip selected metadata components from images as they are exported. You can use it, for example, to remove the embedded thumbnail and any Lightroom “develop” metadata, while retaining other metadata, such as the exposure settings, lens information, copyright, etc.

Links for download and install instructions are at right; continue reading below for a description of the plugin's features.

(Note: Please see the known issues before reporting bugs.)

Overview

Here's a screenshot showing the options and features of the Metadata Wrangler as it appears in the Export Dialog, as of its initial public release:

What metadata you choose to strip – and to leave intact – can vary greatly depending on your intended use. For example, it makes sense to strip at least the embedded thumbnail from small exports that are themselves intended to be used as thumbnails. In such a case, it may well make sense to strip everything but copyright information, to keep the file size small.

On the other hand, it may well make sense to preserve most metadata on images intended for upload to a photo-sharing site, yet remove the embedded thumbnail that does little but increase the file size (and hence the file-upload time).

In any case, only the exported copy of the image is affected; both the original image and the Lightroom library are never changed by this plugin.

It's a “Filter”

I call the Metadata Wrangler an “export filter”, but in the official Lightroom vernacular, it's a “post-process action”. The point is that unlike a full export plugin (such as my “Export to Flickr” plugin), this filter (post-process action) can be used with any export from Lightroom. It can be used in conjunction with the standard “Files on Disk” export, in conjunction with one of my other plugins (e.g. “Export to Zenfolio”, “Export to PicasaWeb”), or any other third-party export plugin.

Metadata Can Be a Bit Tricky

I don't know that there's a good reason for it, but it's turned out that image-file metadata formats have grown into somewhat of a mess. Luckily, Phil Harvey has created the most excellent exiftool library that makes this plugin's work much easier. It's the same metadata-handling library used for the back end of my online Exif viewer. If you find this Metadata Wrangler plugin useful, please consider making a donation to the Exiftool Project in thanks.

Nevertheless, some of the “metadata mess” remains exposed to you, the user, as evidenced by the mishmash of XMP blocks. Here's part of the Metadata Wrangler in Lightroom's export dialog dealing with XMP blocks....

You can have all XMP data preserved or stripped by clicking on the “preserve” or “remove” next to the “XMP Blocks” label at the top, but if you want to be selective, you may have to do some research to see in which block or blocks the data you're interested in lies. It's a bit cryptic for the non-engineer, but the XMP-block info at the exiftool site lists exactly what fields are in each block. (The “XMP Info” button in the dialog links to that page as well.)

Two of the XMP blocks are fairly straightforward. The XMP “crs” block contains all the information about Lightroom develop adjustments (crop, exposure, localized corrections, etc.). You'll want to strip this block if you want to hide – or just don't feel the need to include with the image – all the develop changes you've made to an image.

The XMP “exif” block contains a repeat of most of the Exif data represented individually lower in the dialog. I'm not sure that there's 100% coverage, but I generally strip it unless I intend the exported image to be for some kind of archive.

Presets

The Metadata Wrangler supports its own preset mechanism. The dropdown near the top of the Metadata Wrangler export-dialog section allows you to create and recall presets of exclude/preserve decisions:

“Preserve Metadata” and “Remove Metadata” are standard presets that adjust the settings to save/remove all metadata. You can create a new preset by making some change to the dialog settings, then choose “save current settings as a preset”.

The current settings for the Metadata Wrangler are also part of any Lightroom Export Preset that you create while the Metadata Wrangler is installed and enabled. Note that the individual settings are saved to the Lightroom export preset, rather than any Metadata Wrangler preset name that might be in effect. This means that if you create a Lightroom Export Preset and then later change the meaning of a Metadata Wrangler preset, that change is not reflected back into the Lightroom Export Preset. (This paragraph is a bit confusing, sorry.)

Metadata Not Explicitly Listed...

The bottom of the dialog section includes a catch-all item that governs how the whole plugin approaches its work:

When “Remove” is selected here, all metadata is removed, and then only items explicitly listed as “Preserve” elsewhere in the dialog are added back. Conversely, when “Preserve” is selected, the items explicitly listed as “Remove” are manually removed from the exported image.

I believe that the end result is always the same – that all metadata that could be in the image is listed earlier in the dialog – but I've included this option as a “just in case”. When I'm exporting small images for use as thumbnails on my site, for example, I strip everything except what I explicitly want to keep: the ICC Color profile, and the copyright/artist information.

Version History

20081122.30	No problems from the upheval recently, so pushing back the expiration a bit.
20081121.29	Try#3 at this fix. Perhaps I shouldn't be programming when I have a cold....
20081120.28	Grrr, build problem held back the fix in .27. This should actually have the fix this time.
20081120.27	Fixes the Undefined subroutine &Digest::MD5::md5 error that some people are seeing.
20081119.26	Added some more logging to help debug the Undefined subroutine &Digest::MD5::md5 error that some people are seeing.
20081117.25	No new functionality in this version, but a huge upheaval in the underlying code to repair an unfortunate design choice I made early on in the development that had limiting consequences I'd not foreseen. There are likely bugs introduced in this version, and as such, it has a short expiration date to encourage updates as those bugs are reported and fixed. If you do run into an error, please send (via email) the log referenced in the upper-right of the Plugin Manager. Thanks.
20081113.24	Added "enabled" to the status line when it's enabled, just to be clear. Attempted to address a problem that I didn't think could happen, but apparently has.
20081031.23	Fixed a but wherein keywords were getting flattened in some situations.
20081030.22	Added a bit of logging to try to track down a problem.
20081004.21	Fixed a situation that might have caused trouble when running two exports in tandem.
20080923.20	Sigh, just realized that the "check for new version" stuff did break in 2.1. Totally my fault, sorry. Fixed.
20080923.19	Arrrgh, my plugin build system has been broken since returning to Kyoto two weeks ago, thereby causing new installs of this plugin to not work. Sorry! Should be fixed now.
20080916.18	Finally have the upgrade button working on both Win and Mac. Since I returned home last week, I now have access to both kinds of machine for the first time since LR2 was released. I can sum up the 5 hours I spent wrestling with the unzip code in three word: I hate Windows. Microsoft owes me five hours of my life back. Note that you may have to install this one by hand in order to get the newly working upgrade button... it's the next upgrade that should be easy-as-click.
20080831.17	Handle a race condition in the upgrade logic that sometimes results in a superfluous "You have version XYZ, but version XYZ is now available" message
20080831.16	Made the switch among presets a bit more efficient, and perhaps fixed a bug related to the preset name not updating in response to changes made in the various selections when switching among Lightroom export presets. (I say perhaps because I could no longer replicate the bug I thought I was seeing, but I don't think I changed anything that would have fixed it, so maybe there really was no bug in the first place? I dunno. In any case, it's fixed. )
20080828.15	Minor tweaks
20080828.14	A few more tweaks to report a failed upgrade attempt a bit more clearly
20080828.13	When upgrading, ignore a status of “50” (which means “out of disk space”) from the unzip the plugin performs. It seems Windows often reports this status even when there's plenty of disk space left, so until I can understand it better, I'll just ignore that code.
20080817.12	Lots of little tweaks as I cleaned things up. Added a bunch of stuff to the Plugin Manager, including a “What's New” button that shows up next to the “Upgrade Now” button when a new version is available.
20080814.11	Fixed infinite cycle of 'assert' messages one might get in odd situations
20080811.10	Moved and renamed the debugging logs to a temporary folder, and added log Show/Delete buttons to the plugin's custom section of the Plugin Manager.
20080808.9	Fixed the "LrShell" problem while using the one-click plugin upgrade.
20080807.8	Fixed the "strict.pm" error that Windows users were seeing.
20080807.7	Updated the plugin links to refer to the proper page, rather than my blog.
20080806.6	An attempt to fix the "Access to undefined global: quote" bug.... we'll see.
20080731.5	Fruits of the debugging... should now work for more people
20080730.4	More debugging stuff...
20080730.3	Added more debugging to the log file ("lr-plugin.log" in the Documents/MyDocuments folder) to help debug when things don't work.
20080729.2	Cosmetic change: swapped the section-heading "preserve" / "remove" buttons to match the order of the columns.
20080729.1	Initial public release