Patent ID: 8428437
Filing Date: 2013-04-23
Classification: H04N

Abstract:
1. A playback device for playing back a subtitle stream in synchronization with a video stream, the playback device comprising: a video decoder operable to decode the video stream; a subtitle decoder operable to decode the subtitle stream to obtain a bitmap of a subtitle; and a color conversion unit operable to convert bit values of the bitmap into display colors based on a color lookup table, the display colors including a character color, a background color, and one or more gradation colors for gradation between the character color and the background color, and the color lookup table including pieces of color information corresponding one-to-one to indexes of the bit values of the bitmap, wherein, prior to the conversion of the bit values of the bitmap into the display colors, the subtitle decoder: wherein a number N of gradation colors used for the gradation in the period is calculated according to the following formula: the number N of gradation colors=(2