Street Photography Magazine

one that can’t necessarily be displayed,
interpreted or searched by photo
management software.
Editing Exif Data: Exif is not just readable
but also editable. Generally, Exif data fields
whose content can be altered by image
editing processes – such as color space, image
orientation and size – are automatically
updated when changes are applied, whereas
data specific to the shot itself (such as the lens
or the exposure time ) remains unaltered. If
you want to freely edit all Exif data fields, you
will have to use tools likeEXIFeditor, ExiferB
and ExifTool(all included on this issue’s
free DVD). This type fo tool is extremely useful
if, for example, you set your camera’s
date incorrectly and have to change your

image metadata accordingly. Non-standard

alphanumeric characters are not generally

supported by Exif and IPTC metadata fields

(see the box on page 121). The latest Exif

release from January 2012 defines how all Exif

fields can be saved in XMP format.

IPTC – Custom Metadata

The IPTC-NAA metadata standard, commonly

known as IPTC, was formulated in the 1970s

in cooperation with the International Press

Telecommunications Council. This standard

allows users to enter their own data in the

available fields, providing a flexible custom

keywording tool. The IPTC standard defines

both the list of fields (which is the same as

those found in the Exif standard) and their

formats, which are different from those

defined by the Exif model. Virtually all relevant

(standardized) metadata that is relevant to

photography is written to an images file’s

header. Writing metadata directly to the

image data is also possible for RAW files, but

is not generally recommended because the

lack of generally accepted standards creates

incompatibility issues.

Always use the manufacturer’s own

metadata editor if possible (in Nikon’s case,

Capture NX 2) or use a dedicated metadata

format such as XMP that is capable of creating

separate sidecar files.

Even though the IPTC standard enjoys

worldwide acceptance, there is a strong case

Image Database Software | Metadata

Sidecar files with formats

such as XMP and

picasa.ini help to

overcome the limitations

of existing metadata

standards and RAW

compatibility issues.

Metadata saved in a

separate file protects the

original image data, but

you have to take care not

to break the connection

between an image and its

sidecar file – for example,

by manually renaming

one or the other.

There is a list of supported software at

http://www.iptc.org/site/Photo_Metadata/Software_list that

includes manufacturer’s own data on how various programs

handle IPTC metadata.

A closer look at the list reveals just how neglected the

implementation of current metadata standards is. Much of the

data is either old or no longer relevant because manufacturers

have introduced new program versions without bothering to

update the relevant IPTC information.

Instead of studying an out-of-date list, reverse engineering is a

much more reliable way to find out which metadata standards and

which data fields have been implemented in a specific program.

Don’t Forget to Check IPTC/XMP Compatibility