视频字幕能够给人们提供高度浓缩的与视频内容相关的信息 ,但字幕通常均以图象方式存在于视频、图象中 ,为了提取视频字幕 ,提出了一种基于局部能量的视频字幕分割方法 ,该方法利用局部能量与图象中边缘、轮廓特征之间的对应关系进行字幕的自动分割 .为了快速地进行局部能量的计算 ,在分析局部能量模型基础上 ,将局部能量计算方法进行了推广 ,即先通过选用具有对称性的双正交小波基及 Hilbert变换 ,构造了适于局部能量计算的 90°相移滤波器 ,然后通过多分辨率小波变换实现了信号的多分辨率频带分割 ,并在此基础上计算局部能量 .实验结果表明 ,该方法可获得较好的分割效果

Caption text presented in the video plays an important role in video retrieval and browser as it provides highly condensed information about the contents of the video. The caption text only can be used after it is extracted from video. According to Morrone's phase congruency theory, image features such as edges, shadows and bars always occur at points of maximum phase congruency, and the maxima of local energy occur at points of maximum phase congruency. Based on this theory, a video caption text segmentation approach is presented in this paper. Instead of Morrone's approach in calculating of local energy, we extended Morrone's approach through constructing a quadrature pair filter from a biorthogonal wavelet by Hilbert transform. The local energy is then calculated from the multiresolution decomposed image in octave bands. According the relationship between local energy and caption text's edge features, we then segment the image using local energy projection. This is the first step of caption segmentation. After that, colour segmentation can be applied to the first segmentation results. The experiments in this paper show that this approach can achieve good caption region segmentation results.