Query By Fax Matching Module

[Module Features] [Module Properties] [Technical Description] [Example Results]

Module Features

This module attempts retrieval when the query image is a low quality monochrome image, for example a facsimile of a painting which is in the database.

The module is good for retrieval of images based on a known query image if the retrieved images are required to have a similar layout of dark and light pixels. It is not suitable for retrieval of images based on a query image which is only part of a complete image.

Module Properties

Module Speed	Very Fast
Module Accuracy	Low

Technical Description

The query by fax is based upon a set of PWT measures of the image at various threshold levels of a monochrome instance of the image. A QbF feature vector consists of 99 PWT features at various levels of threshold (between 1% black and 99% black) of the image.

Query By Fax: Database Images converted to 99 PWT levels on left, query image on right.

Matching is performed by a simple step process:

Make query fax image binary (it almost is anyway, but this enforces it)

Detect what percentage of the image is black/white.

Select from the set of PWT vectors for a database image the vector which is of the same percentage black/white.

Perform a PWT match, as described on the PWT help page.

Example Results

The following is an example query giving what would be considered good results.

Note: The matching is based upon the layout of dark and light pixels.


Query	1	2	3

	4	5	6

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