纹线距离在自动指纹识别中有着广泛的应用.但迄今为止,研究纹线距离估计的文献并不多见,且所述方法对质量较差的指纹图象的处理效果也不尽如人意.为了对质量较差的指纹图象进行可靠的纹线距离估计,提出了一种基于统计窗的纹线距离估计方法,该方法是首先将指纹图象分成互不重叠的块,并为每块图象定义统计窗和基线,然后采用距离统计的方法来获取统计窗内的指纹纹线分布,进而估计每块图象的纹线距离.部分典型图象的实验结果证明，该方法是有效的.

Ridge distance is an intrinsic texture property of fingerprints and it has important application in automatic fingerprint identification system. However, up to now, only several literatures touch ridge distance estimation deeply. Ridge distance estimation is developed in this paper and a method based on statistical window for ridge distance estimation in fingerprint images is brought out. A fingerprint image is divided into non-overlap blocks and a statistical window and a base line is defined for each block image. A statistical method is used to acquire the distribution of ridge in the statistical window and the ridge distance of a block image is estimated. Even to block images in which ridge directions vary acutely only if the dominant direction is existent or to block images in which noises are comparatively serious, such as much ridge breaks, the method still can estimate ridge distance reliably. Tests with some typical images show the good performance of the method presented in this paper.