为了提取区域边界，可以对图像直接运用一阶微商算子或二阶微商算子，然后根据各像点处的微商幅值或其他附加条件判定其是否为边界点。如果图像中含有较强噪声，直接进行微商运算将会出现许多虚假边界点。-.Using the feature of distinct edge contour existing between the text and the background regions in color images, a novel text extraction algorithm—CEMA(Color-edge detection, Morphology, logic operator“AND”) is proposed in this thesis for video images.