EXIF — IPTC — XMP
IPTC — XMP — EXIF
The alphabet soup. When using Lightroom, we have to deal with IPTC, XMP and EXIF data but what are they?
IPTC: International Press Telecommunications Council
It was created for the wire services in the time that news people used faxes. Remember fax machines in the 70s and the 80s?1 It keeps track of:
- Caption
- Credits
- Copyrights
- Bylines
- Locations
- ANPA, American Newspaper Publishers Association, news categories
- …
XMP: Extensible Metadata Platform
It was created by Adobe to convert the IPTC to XML. XML = Extensible Markup Language. The XMP is a separate text file, often referred as the sidecar, because it has to ride along with the photo. If you loose or delete the XMP file, you will loose of the extra information for managing your photos. The format is very similar to HTML. Once the IPTC information is in a XML format, it can easily be ingested and processed by databases like Oracle and Microsoft SQL Server, so it can be searched. Here's the beginning of one of my XMP files.
<x:xmpmeta xmlns:x="adobe:ns:meta/" x:xmptk="Adobe XMP Core 4.2-c020 1.124078, Tue Sep 11 2007 23:21:40 ">
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
<rdf:Description rdf:about=""
xmlns:tiff="http://ns.adobe.com/tiff/1.0/">
<tiff:Make>Canon</tiff:Make>
<tiff:Model>Canon EOS 7D</tiff:Model>
<tiff:Orientation>1</tiff:Orientation>
<tiff:ImageWidth>5184</tiff:ImageWidth>
<tiff:ImageLength>3456</tiff:ImageLength>
</rdf:Description>
...
It keeps on for another 321 lines and that's only for one photo. But as you can see, it's something very simple than can be easily read. What goes into the XMP file?
- All of the EXIF data
- All of the IPTC information
- Labels, ratings, comments…
- All the steps taken by Lightroom during the edits, such as the crops…
- Pretty much anything that you want since you can create you own tags, that's why it's called “extensible”.
EXIF: Exchangeable Image File Format
Camera and photo information about the photo taken. It's stored in the JPEG or the RAW photo file itself. That information is also duplicated in the XMP sidecar if you Save Metadata To File. It includes:
- Timestamp
- Shutter speed
- ISO rating
- Focal length
- …
1 I do, we had 2 fax machines on 2 phone lines because it was so slow at 1200bps and a 10 page document would take 15 minutes to be received, then we upgraded to a computer/fax server that would run at 9600bps. ↑
Tags: Dam | Lightroom | Lightroom-Reference | Lightroom-Why | Technical
IPTC — XMP — EXIF
The alphabet soup. When using Lightroom, we have to deal with IPTC, XMP and EXIF data but what are they?
IPTC: International Press Telecommunications Council
It was created for the wire services in the time that news people used faxes. Remember fax machines in the 70s and the 80s?1 It keeps track of:
- Caption
- Credits
- Copyrights
- Bylines
- Locations
- ANPA, American Newspaper Publishers Association, news categories
- …
XMP: Extensible Metadata Platform
It was created by Adobe to convert the IPTC to XML. XML = Extensible Markup Language. The XMP is a separate text file, often referred as the sidecar, because it has to ride along with the photo. If you loose or delete the XMP file, you will loose of the extra information for managing your photos. The format is very similar to HTML. Once the IPTC information is in a XML format, it can easily be ingested and processed by databases like Oracle and Microsoft SQL Server, so it can be searched. Here's the beginning of one of my XMP files.
<x:xmpmeta xmlns:x="adobe:ns:meta/" x:xmptk="Adobe XMP Core 4.2-c020 1.124078, Tue Sep 11 2007 23:21:40 ">
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
<rdf:Description rdf:about=""
xmlns:tiff="http://ns.adobe.com/tiff/1.0/">
<tiff:Make>Canon</tiff:Make>
<tiff:Model>Canon EOS 7D</tiff:Model>
<tiff:Orientation>1</tiff:Orientation>
<tiff:ImageWidth>5184</tiff:ImageWidth>
<tiff:ImageLength>3456</tiff:ImageLength>
</rdf:Description>
...
It keeps on for another 321 lines and that's only for one photo. But as you can see, it's something very simple than can be easily read. What goes into the XMP file?
- All of the EXIF data
- All of the IPTC information
- Labels, ratings, comments…
- All the steps taken by Lightroom during the edits, such as the crops…
- Pretty much anything that you want since you can create you own tags, that's why it's called “extensible”.
EXIF: Exchangeable Image File Format
Camera and photo information about the photo taken. It's stored in the JPEG or the RAW photo file itself. That information is also duplicated in the XMP sidecar if you Save Metadata To File. It includes:
- Timestamp
- Shutter speed
- ISO rating
- Focal length
- …
1 I do, we had 2 fax machines on 2 phone lines because it was so slow at 1200bps and a 10 page document would take 15 minutes to be received, then we upgraded to a computer/fax server that would run at 9600bps. ↑
Tags: Dam | Lightroom | Lightroom-Reference | Lightroom-Why | Technical
