However, it takes more than recognizing a friendly face to extract oneself out of a lonely state.

然而，如果想要让自己脱离寂寞，绝不止是认清楚一张友好的脸孔那么简单。

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We do orthogonal wavelet transform of a face image, get its four sub images of different frequency bands, then respectively extract their singular value features.

对人脸图象作正交小波变换，得到它在不同频带上的四个子图象，然后分别提取奇异值特征。

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It is still a difficult problem to extract features from face images efficiently.

如何有效地从人脸图片中提取人脸特征一直是一个难题。

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