變形網格及其在圖像識別中的應用
Application of Deformable Grid in Image Recognition
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摘要: 網格特征是圖像識別中一類重要特征，而變形模板對于復雜的圖像識別問題如字符識別、數字識別、圖標識別等表現出很好的性能，但變形模板很費時。該文針對網格特征提出了變形網格，并分析了變形模板與變形網格之間的近似等價性。所提方法對網格進行變形而不是對圖像變形，因而速度比變形模板快得多，而且性能相差不大。把這種方法分別應用于圖標識別和脫機手寫漢字識別。圖標識別實驗中變形模板使識別率提高了7.5%，而變形網格使識別率提高了7.3%、手寫漢字識別實驗中變形模板使識別率提高了6.1%，而變形網格使識別率提高了5.8%?？紤]到變形網格比變形模板快得多，所以這種方法是有優(yōu)勢的。Abstract: Grid feature is a popular feature extraction scheme in image recognition, and usually higher performance could be obtained with the help of deformable template, espe-cially in such difficult image recognition tasks as character recognition, digit recognition, logo recognition etc. The critical shortcoming of deformable template is time-consuming. In this paper the method of deformable grid is proposed to compensate for the shortcoming of deformable template. Firstly certain grid must be superimposed on image, then unlike de-formable template where deformation is applied to image, various deformations are applied to grid. Because the number of grid is much less than that of pixels in image, the method is much more timesaving comparing to deformable template. The approximate equality of deformable template and deformable gird is also analyzed. The method is evaluated by two image recognition experiments, namely, logo recognition and off-line Chinese character recognition. The improvements in recognition rate by 7.3% in first experiment, and 5.8% in second one are obtained by the use of deformable grid.
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