Visual Inspection of Lumber

The goal of our research is to develop machine vision technology for color based inspection and grading of dried lumber boards. The principle used is to eliminate most of the sound wood regions from further scrutiny at an early stage of processing.

The used color features have a basis in spectrophotometric measurements of the material (left). Also a part of our test material is shown (right). The image acquisition has been performed with a three-chip camera at about 0.5 millimeter resolution. Also a prism based color line-scan camera has been used.

Picture Picture


Four 25cm long spruce images are shown below in more detail.

Picture Picture Picture Picture

The material has been divided to about 2.5-by-2.5 centimeter regions that have been classified manually to about forty categories.

Wood DefectsExamples of the most common defects of wood

A database of knot images from spruce and their classifications is available. The database has been prepared carefully to ensure consistency with the Nordic standards. To gain understanding of the defect classes on wood see the examples and look at the explanations for various knots.

We also offer a part of our extensive set of wood images that have been manually classified region-by-region. Larger amounts of data could be made available for scientific users on request. For instance, we have a huge set of manually classified pictures of up to 6 meter long boards. This exceptionally high quality imagery has been acquired using a prism-based color line-scan camera by VTT Building Technology.

If you use the knot or wood samples for any purpose, please, remember to refer to their origin.


A paper on wood inspection methodology is available here in PDF-format:
Silven, O., Niskanen, M., Kauppinen, H. (2000) Wood inspection with non-supervised clustering, COST action E10 Workshop - Wood properties for industrial use, Espoo, Finland, June 18-22.

Presentation slides (in Finnish) on visual learning


See also our other research activities.


Other wood related web pages:
Laboratory of Wood Technology Helsinki University of Technology, Finland
VTT Building Technology: Wood Technology
Olli Silven (olli.silven@ee.oulu.fi)