There are two kinds of metadata: Machine-generated and User-generated.
Most of us know a camera adds metadata to every image. Metadata can be viewed in Photoshop by using the File > File Info command. Metadata can also be viewed in Bridge, Lightroom, and other editing, browsing, and management programs.
The metadata written by the camera (or scanner) is written into the image file using the Exchangeable Image File Format, usually referred to as EXIF data. EXIF data contains a range of image information: size of the image, the camera and the exposure settings used to create it, and the date the shutter was released. If your camera allows you to add a comment to each image, that is a good place to add your copyright statement to each image every time you trip the shutter.
Adding, Subtracting Metadata
Some photographers don’t want proprietary, exposure, or other information included in the metadata in their images. Editing EXIF metadata can’t be done in Photoshop or other digital asset management (DAM) software. To do edit EXIF you need to use a stand-alone EXIF utility like PhotoMe or EXIF/Tool. However, metadata can be entirely removed by creating a new file in Photoshop or similar applications and pasting the image into the new file.
Any information added to an image file after capture is in the International Press Telecommunications Council (IPTC) schema. IPTC contains fields (author, job title, address, phone, headline, description, keywords, etc) for easily embedding the same information into multiple files at the same time.
Minimum Requirements
Trade associations, standards organizations, and industry experts pretty much agree the minimum IPTC metadata added should include:
· Creators name
· Contact info
· Copyright Notice
If you are licensing your image to a client (print release, etc) there is an IPTC field, Rights Usage Terms, to convey those license terms.
A very valuable IPTC field is for keywords. Keywords can be used to increase revenue through licensing stock images since only with keywords can your images be easily found. Many portrait and wedding photographers fail to fully exploit the income that can be gained from making their vast collection of images available for stock.
IPTC also has field so you can enter metadata on: location, city, state, country, or country code as needed.
By embedding your contact info into every image that leaves your computer, you increase the chance someone wanting to use your image can find you.