关键词: 频率谱, 傅里叶变换, 轮廓特征提取, 唐卡图像, 分类

Abstract: This paper presents a method based on the variation of frequency spectral to express contour feature，which has been successfully applied to classify headdresses of religious portrait Thangka image.Mark the headdress region of the image，segment the marked area by the means of basic global threshold and user observation histogram to choose threshold value.Transfer the pixels in the image into points in the coordinate system，and extract the typical contour points.Transfer the typical contour points into frequency region space through Fourier transform，apply the relatively small frequency spectrum values as the contour features.The experiments show that the effective classification of headdresses can be done by extracting the features of headdresses in this paper.

Key words: frequency spectral, Fourier transform, contour feature extraction, Thangka image, classification