1. A method for detecting and eliminating a flash scene in digital video, the method comprising: inputting a video sequence; extracting a sequence of frames of the video sequence; calculating each luminance difference for every two adjoining frames; making a histogram recording the luminance differences among the frames; determining a threshold according to the histogram, which is used to detect the flash scene in the video sequence; categorizing the flash scene; and eliminating the flash scene by ignoring the flash scene, replacing the flash scene with an average value around the flash scene in the video sequence, or recalculating the flash scene, wherein in said categorizing the flash scene, a Type 1 is determined as two consecutive luminance differences larger than the threshold, the method further comprising: (a) comparing each luminance difference with the threshold predefined; (b) calculating a peak difference between two luminance differences; (c) comparing the peak difference with a predefined percentage; and (d) determining the Type 1.