How systematic image keywording works

What is referred to as keywording is also known as indexing. In English, several terms are common, including tagging, keywording, and subject indexing. In each case, the meaning is the same: assigning descriptors to documents, media, and other content. Descriptors are descriptive text elements, commonly known as keywords.

The goal is to improve findability within an archive or database. This article focuses on digital media and specifically on photos.

The value of good keywording

The main reason has already been stated. Keywording improves the findability of files within a digital database.

In addition, it creates structure and overview. Keywords are typically not managed as a flat list but within a hierarchy. This makes search more robust and ensures more consistent use across collections.

Searching a photo library by keywords is more efficient than navigating folder structures. Folders can still be useful, but they become limiting once the library grows. From roughly 10,000 images onward, systematic keywording is a practical investment.

Completeness matters. If only part of the library is keyworded, keyword search will have gaps. Systematic keywording requires consistency.

Keywording correctly in three steps

Keywording larger image collections usually requires dedicated software. Operating system features are typically not sufficient. Windows Explorer supports basic keywording for formats such as JPEG or TIFF, but it rarely supports structured, controlled vocabularies.

The following sections help assess whether available software meets the requirements for systematic keywording.

Core rule: control the vocabulary

Entering whatever comes to mind leads to inconsistencies. Professional keywording requires a controlled vocabulary, often referred to as a thesaurus.

Key questions include:

• which terms are part of the vocabulary
• which terms are excluded
• how terms are structured and maintained

Step 1: define the right categories

Start by identifying the most common topics in the collection. From this, define categories as the top level of the hierarchy.

Example for nature photography:

• animals
• plants
• fungi

Step 2: use broader and narrower terms

Categories are broader terms. Lower levels refine the structure.

Example within animals:

• mammals
• birds
• amphibians
• reptiles
• fish
• insects

Narrower terms under mammals:

• dogs
• cats
• primates
• rodents

The lowest level typically contains a specific label, such as a species name or a breed.

Example hierarchy:

• animals
• mammals
• dogs
• domestic dogs
• dachshund
• smooth haired dachshund

The same pattern applies to other domains.

Example for technology:

• technology
• communications technology
• mobile telephony
• smartphones
• iPhone
• iPhone 14 Pro Max

Keywording concepts

Keywords do not need to be limited to objects. Concepts expressed in images can also be keyworded, for example emotions, moods, or styles.

Example:

• concepts
• image mood
• romantic

Hierarchical keyword systems are often described as a keyword tree. A structure that is too deep becomes hard to maintain. A maximum depth of five to six levels is often practical.

A key benefit of the hierarchy is reduced manual input. In strong keywording solutions, entering a narrow term automatically includes its broader terms.

Example entering smooth haired dachshund adds:

• animals
• mammals
• dogs
• domestic dogs
• dachshund
• smooth haired dachshund

Step 3: add synonyms

Professional systems support synonym management, which improves search and saves time.

Example synonyms for mammals:

• mammal
• Mammalia
• mammals

Example synonyms for dachshund:

• dachshund
• dachshunds
• Teckel

Once synonyms are defined, entering a single term can generate a wide set of relevant search terms.

Example entering smooth haired dachshund results in terms such as:

• animal
• animals
• fauna
• mammal
• mammals
• Mammalia
• dog
• dogs
• Canidae
• domestic dog
• domestic dogs
• Canis lupus familiaris
• dachshund
• Teckel
• smooth haired dachshund

Special cases and limitations

Hierarchy and synonyms increase recall:

• hierarchy supports searches using broader terms and combinations
• synonyms capture alternative spellings

In some cases, storing common misspellings as synonyms is useful, especially when external users search.

Examples:

• Albatros instead of Albatross
• Ginkgo instead of Gingko

Some ambiguities cannot be fully resolved. Eiffel Tower is a typical example. The term usually refers to Paris, but there are other locations using the same name. Such conflicts require editorial decisions.

Keyword categories beyond content

Beyond content keywords, there are categories that can be applied consistently across images.

Formats

Common format keywords include:

• landscape, horizontal
• portrait, vertical
• square
• panorama, horizontal or vertical

Modern keywording tools can add this information automatically.

Focal lengths and zoom levels

Common photography related categories include:

• telephoto
• close up, macro
• micro
• wide angle
• fisheye
• perspectives

Common camera perspectives:

• bird’s eye view, aerial
• worm’s eye view
• central perspective, eye level
• vanishing point perspective

Framing and focus

Common terms include:

• front view
• rear view
• side view
• top view
• full body
• three quarter view
• portrait

Additional composition attributes

Frequently used attributes include:

• bright or dark background
• indoor or outdoor
• studio shot
• cut out
• copy space
• rule of thirds
• dominant colors
• long or short exposure

Stock photography categories

Stock photography often uses additional keyword groups.

People count:

• no people
• 1 person
• 2 people
• group of people

Place and time:

• country, region, city
• century, decade, year
• season, month

Legal attributes:

• model release available
• property release available
• royalty free
• rights managed
• editorial use only
• commercial usage possible

Example of good keywording

The final section applies the approach to an example. This is not about captions or titles, only keywords. For clarity, keywords are grouped.

Example image: smooth haired dachshund on stairs

Content keywords for the above image:

• animal
• animals
• fauna
• mammal
• mammals
• Mammalia
• dog
• dogs
• Canidae
• domestic dog
• domestic dogs
• pet
• pets
• Canis lupus familiaris
• dachshund
• Teckel
• dachshund
• smooth haired dachshund
• spotted
• multicolored
• male
• scarf
• stairs

Concept keywords

• cute
• loyal
• loyalty
• dog look

Formal keywords

• photography
• color photo
• landscape, horizontal
• portrait
• side view
• central perspective
• looking at camera, eye contact
• outdoor
• brown
• brown tones
• no people