The present invention determines whether
fingerprint ridgeline information is contained within the
fingerprint image using a simple method by considering the properties of the
fingerprint ridgeline. In this
fingerprint image evaluation method, a density is obtained of a reference point provided within the
fingerprint image and a density is obtained of a comparison point that is shifted from the reference point by a predetermined distance. The amount of fingerprint ridgeline information contained within the
fingerprint image is evaluated based upon a difference between the density of the reference point and the density of the comparison point. In this fingerprint
image evaluation method, the characteristic of the fingerprint ridgeline, in which a fingerprint furrow line exists proximally to the fingerprint ridgeline, is utilized. Therefore, erroneous determinations can be prevented in which an image, which is not in fact a fingerprint image, is determined to be a fingerprint image. In addition, it is only required to obtain the density of the reference point and the density of the comparison point, and to calculated their difference. Therefore,
time consuming processing is not necessary, such as is required to extract characteristic points from a fingerprint image.