Fractal texture features based on optical density surface area. Use in image analysis of cervical cells.

The spatial distribution of the optical density of an image of a cell nucleus can be imagined to resemble a rugged surface in a three-dimensional space. The area of this surface can be measured using different unit-sized squares, yielding different values for the total area depending on the unit size. A fractal dimension can be calculated from the relationship between the unit size and the overall area measured; this fractal dimension is characteristic of the surface measured. This technique was applied to extract three new nuclear features from stained cervical cells. These new features were useful for the computer discrimination of normal and premalignant cervical cells. The features are defined, and their discriminating power is compared to that of some other nuclear features.