Objectives

The objective of the PhoTex project is to develop a new methodology for texture classification based on the direct use of surface gradient (relief) and surface reflectance (albedo) information. This will enable the design of image texture analysis systems that exploit and take into account the illumination conditions and the three-dimensional nature of texture.

It uses photometric stereo to determine surface gradients. We are using this technique to extract and separate surface relief and albedo information. This will enable classification to be performed by comparing texture features computed directly from surface properties rather than image intensity values. Thus we will for instance compare surface relief against surface relief rather than pixel patterns against image data.

Such an approach can:

• provide true surface-rotation invariant (as opposed image-rotation invariant) classification,
• compensate for illumination changes that cause catastrophic failure of conventional texture classifiers, and
• improve the accuracy of texture classification and defect detection.