"Metadata" has been introduced in other CarLibrary.org webpages. Those pages also explain how car historians, collectors, museums and collections can use several types of software to create and maintain traditional inventories or digital archives.

This webpage describes using the open-source ExifTool software and a separate open-source add-on program, the ExifToolGUI (Graphical User Interface), to improve the identification - and eventual classification - of digital photos and scanned documents in many image formats and PDF files through the use of "embedded metadata".

The ExifTool provides a very powerful tool to read metadata from an entire folder of images or documents- or any set of folders and subfolders of digital files - into a Comma Separated Value (CSV) file. This CSV file is easily opened in Excel or other spreadsheet program.  In the Excel (spreadsheet) file, incorrect or missing metadata of each file/record/image can be corrected or added.  That Excel file can be used to import this "inventory of digital assets" into digital library software (Greenstone), a database or a Collections Management System (CMS).  It can also be used to "write" the updated metadata back into the image (or other) digital files. Although the ExifTool must be used from Windows (or Linux) through the "command line", which may be daunting for users accustomed to a Windows or Mac graphical interface, its power to create archive/collections inventories - and files with useful embedded metadata - should justify the effort necessary to master its use.  Highly recommended!

This guide's sections are:

1. ExifTool - Reading and Writing Embedded Metadata

a. More Complex Directories with Thousands of Photos

b. Writing Metadata into Photos

2. ExifToolGUI

3. Summary of the ExifTool and ExifToolGUI

a. Videos

b. Recommendations

1. ExifTool - Reading and Writing Embedded Metadata

Phil Harvey's ExifTool, is described to have the ability to extract, add, copy or move nearly all types of metadata, not only EXIF metadata.  It will display metadata in PDF, Word, Excel and MP3 files and edit metadata in image and PDF files.  The basic program is used from a "command line", but with the correct configuration, it is very powerful and has proven to "do everything" to image metadata. Downloads for Windows, Macs and Linux systems and very complete explanation of its functions are here. 

This webpage is an introduction to using a few of the command line functions.

Download the ExifTool and install as follows:

A.  Go to Phil Harvey's website and use one of the download links near the top of the page.  The "Windows Executable" is recommended for Windows systems and there is a Mac OS X package just below.

B.  Installation instructions are on a link just below the download links.  On Windows systems, follow the "exiftool.exe" move instructions carefully so the program will work from all directories.

C.  As noted in these instructions, you must first get to the Windows command prompt by selecting "Run..." from the Windows "Start" menu, then type "cmd" and press Return. It appears that you have time-traveled to the '80s world of DOS!  Then type "exiftool".

D.  The "exiftool" expects arguments/inputs otherwise it will only display information about the program.  This is a sample command:

exiftool -csv -r -DateTimeOriginal -Description -Subject e:\cars\Vespa\Vespa-Pics > Vespa.csv

Figure 1 shows what this looks like:

Figure 1 - The ExifTool in a Command Window

which gives the result in Figure 2, below.  The "inputs", above, to the tool are:

1.  "-csv"  set the option to produce a "Comma Separated Value" file.  This format can be directly read by Excel.

2.  "-r"  do this recursively (for all files in the chosen directory)

3.  "-DateTimeOriginal" write the metatag "DateTimeOriginal"

4. "-Description" write the metatag "Description" which is the Picasa caption on the image

5. "-Subject" write the metatag "Subject", which is also a Picasa "tag".  Multiple tags can be added in Picasa

6. "e:\cars\Vespa\Vespa-Pics" do this action for all the files in this directory

7. "> Vespa.csv" sends the output to the CSV named file

Figure 2 - the Excel file output from the Vespa.csv file

8.  If the CSV file is opened with Excel, it will appear similar to the one above.  The columns and headings have been formatted to improve readability.  The "Subject" field column will have multiple "tags" separated by commas.  Highlight the entire column and use Excel's "Text to Columns" function in the "Data" menu and choose "delimited" separation and check the "comma" box.  Sort the 'tags" columns one at a time to group similar data together - such as the ID numbers and move them to the relevant "correct" column.

9.  If you will be using ExifTool on a regular basis, you can keep a "library" of commands in a Word or Excel file that can be copied and pasted into the command Window.  To copy or paste, right click in the title bar of the command window and choose "Edit".  Options will pop up, including "Paste".  To adjust the appearance of the command window, choose the "Default" menu item and make desired changes.

For example, "a." below is the original example command; ""b." will produce a similar file from the "Vespa-VBB" directory, but add the "FileName" to the "Vespa-VBB.csv" output file. 

a. exiftool -csv -r -DateTimeOriginal -Description -Subject e:\cars\Vespa\Vespa-Pics > Vespa.csv

b. exiftool -csv -r -FileName -DateTimeOriginal -Description -Subject e:\cars\Vespa\Vespa-VBB > Vespa-VBB.csv

Complete documentation for the ExifTool is on Mr. Harvey's website.  The program may seem complex, but it is potentially powerful.  There are many metadata categories, with many options to read and extract data from files.  However, it you have an extensive photo collection, or similar files to manage, much benefit can be gained by "reading" selected metadata from the files, as shown above, and creating lists in Excel or other database program.

These are the XMP metadata values in the "Dublin Core" category that the ExifTool can read and modify; there are many more categories and hundreds of metadata values:

Tag Name	Writable
Contributor	string+
Coverage	string
Creator	string+
Date	date+
Description	lang-alt
Format	string
Identifier	string
Language	string+
Publisher	string+
Relation	string+
Rights	lang-alt
Source	string/
Subject	string+
Title	lang-alt
Type	string+

These are the metadata values in PDF files that the ExifTool can read and modify (XMP category):

Tag Name	Writable
Author	string
Copyright	string/
CreationDate	date
Creator	string/
Keywords	string
Marked	boolean/
ModDate	date
PDFVersion	string
Producer	string
Subject	string/
Title	string/

a.  More Complex Directories with Thousands of Photos

The example above used a single directory with a small number of files that have been prepared with significant metadata,  How does the ExifTool work with a complex folder/directory with many subdirectories and thousands of photos?

This ExifTool command (from the command line) was used (from the command line) on the "AFNpics" (photos of Frazer Nash cars) directory which had 53 subdirectories and an unknown number of photos/files before its execution. As an experiment, the command was  first used with the "All" parameter: 

exiftool -csv -r -All f:\AFN\AFNPpics > AFNPics.csv

1046 categories of metadata were returned!  More than 95% of these categories were "camera/photo technical type" data, with many category variations from different camera manufacturers of the same basic data.  The CSV output file had far too many columns to display in Excel. 

Figure 2a - Command to run the ExifTool with the "All" parameter.  Note it has "scanned" 53 directories and extracted data from 2058 image files.

To get more useful results, the metadata categories were trimmed down to 43. The command below is the result:

exiftool -csv -r -Artist -Author -Caption-Abstract -Categories -Category -Comment -Comments -Company -Contributor -Copyright -Coverage -CreateDate -CreationDate -Creator -Date -DateCreated -DateTimeOriginal -Description -Directory -DocumentID -FileID -FileName -FileNumber -FileSize -FileSource -FileType -Format -GPSLatitude -GPSLongitude -ImageHeight -ImageSize -Keywords -Label -Location -ModifyDate -ObjectName -PDFVersion -Producer -Relation -Source -SourceFile -Subject -Title f:\afn\afnpics > afnpics4.csv

When it was executed, it produced a very useful Excel file, after some formatting for better display.  Further trials should confirm that the alphabetical order of the metadata categories, the default shown above, can be changed.  This would make the category/column order of CSV output file with a close or exact match to an existing spreadsheet file, therefore eliminating many potential "cut and paste" steps.

Figure 2b - Command to run the ExifTool with a trimmed down group of 43 parameters.  Not all parameters produced useful data.

The screen shot in Figure 2a shows there are more than 2000 photos in the entire "AFNPics" directory.  After running the command shown in Figure 2b, the result was an Excel file with 43 columns and 2058 rows.  From this file, it's easier to pick out the more useful categories, delete the columns with no data (or data not considered useful) and start adding data in the empty cells!

b.  Writing Metadata into Photos

The ExifTool also has the ability to "write" metadata to single files or entire directories.  This is a preliminary guide to this "-tagsFromFile" option:

1.   Extract the metadata from your photos by making a CSV/Excel file as described in the section above.

2.   Inspect the cells for each photo's metadata in the in the relevant rows and columns.

3.   After deciding what needs to be added, fill in the desired metadata in the appropriate cells.  The Excel "copy" and "paste" functions can speed this process.

4.   You can optionally delete rows and columns that have no new data to be added to the photos or for photos that are not to be changed.  In our example from above, the "Description" column/metadata was changed to "Title" and missing data filled in.   New columns were added for "Creator" and "Author".  The Excel file below was saved in "CSV" format.

5.   When saving the Excel file planned for input in the "CSV" format, it's a good idea to use a new file name, such as "Vespa-input.csv", to prevent confusion with the CSV file which extracted the metadata from your photos.

6.  Open a Command window (see step 1.C. above) and change to the drive and directory where your photo to be changed are located.

7.  Run a ExifTool command similar to this:

a. exiftool -csv=vespa-input.csv -ext jpg e:\cars\vespa\vespa-pics\

8.  When the command runs correctly (no error messages), the new metadata will be added to the chosen photos and the original photos will be saved with the "_original" extension added - just in case!   If you get error messages, check your input file to make sure the full path to the "SourceFile" category is all lower case and the cases of the file names match.  If the command still fails to execute, change the output path to lower case.  For example from above, it should be "e:\cars\vespa\vespa-pics\"

This is a screen shots of this command before running:

And the result after running - not overly dramatic!

See Figure 3a below for a screen shot of the ExifToolGUI after this operation.

In October, 2014 this "write" function was used (from a CSV file) to add 14 categories of metadata to 675 travel photos.  This included a unique accession number for each photo.  See the "Videos" section below for more detail.  Very useful and impressive!

The ExifTool has another function to add geo-data to digital photos using a track recorded on a GPS.  The function was tested in early December, 2014 with great success.  Although the mapping accuracy depends on the camera time and date setting be the same as on the GPS device, the photo date and times can be adjusted in program such as Picasa or a sync parameter can be used directly in the ExifTool.  See the full "Geotagging with ExifTool" documentation.

2. ExifToolGUI

3. Summary of the ExifTool and ExifToolGUI