Before extracting the feature of a fingerprint, it is important to separate the fingerprint regions (presence of ridges) from the background. This limits the region to be processed and therefore reduces the processing time and false feature extraction. A correct segmentation may be, in some cases, very difficult, especially in poor quality fingerprint image or noisy images, such as presence of latents. The same information used for quality extraction, such as contrast, ridge orientation and ridge frequency can be used for the segmentation or inclusive the quantified region quality may be used directly by considering as background the regions with quality below some threshold. Normally, the segmentation are also computed by block in the same way as the quality extraction. In the above figure is shown the contour of the segmented region superimposed over the original image.
 original image |
 image with segmentation |