Detection of gradual transitions in video sequences

摘要

A technique is disclosed for detecting gradual transitions between frames of a video sequence such as fade and dissolve transitions. For each frame, the intensity values of pixels at corresponding positions within a window of frames including the subject frame are compared, and signs are allocated to the calculated differences. The number of each type of sign is determined for each pixel position and the larger number of matching signs is assigned as a measure of the monotonicity of the direction of intensity variations at the pixel position between the frame and the surrounding frames. A global monotonicity measure is then calculated for the frame as a whole using the monotonicity values for each pixel position. This is repeated for each frame to generate a temporal sequence of frame intensity change monotonicity measures. Slopes within this temporal sequence representative of gradual transitions between video frames are detected. Alternatively, the values in the temporal sequence are compared with a threshold to identify values representative of gradual transitions between video frames.