Image Databases

Definition

Ø  Computer system where image files are kept in an organised form.

Ø  Software that facilitates organised storage and retrieval of digital images is called Image database system.

Characteristics of Image Database

The main characteristics of image database system

1. possibility to handle large amount of images of different types.
2. possibility for content and similarity based retrieval.
3. possibilities to compose the query of text, images, sketches and making use of colour palette.
4. The query response time is fast.

Global Image Representation

            Traditionally there have been two major approaches for global image representation.

ü  The parametric approach.

ü  The syntactic approach

In the parametric approach image elements are represented by vectors of features ((e.g., colour, Size, etc.), which features can be measured from the images.

In the syntactic representation the image features are represented as sets of symbolic entities, that is an alphabet of image primitives is used.

The image indexing mechanism combines the two approaches and allows quick search based on multilevel index.

The user can make use besides of simple text-based queries, also of tools for drawing sketches, picking colour from colour palette, drawing image element, extracting parts from example images, etc. The searching mechanism combines image and text description of colour, shape and attribute of the image and its elements. The overall description reduces the search.