| 摘要 |
From a frame buffer (23), the image data already written in the addresses which correspond to an image having an arbitrary shape are read from a frame buffer (23), and the values of predetermined bits of read-out image data are altered, and again, the image data are written in the addresses. Further, when the image data of the foreground are read from the frame buffer (23) at predetermined timings, whether the value of each predetermined bit is the altered value or not is checked. In the case of an altered bit value, the image data having the altered bit value is judged to be image data constituting the inside region of a window, and transparency processing or color computation processing of one of the inside and outside of the window are performed. Thereby, the predetermined bits of the image data written in the frame buffer can be altered, and according to this, a window having any complex shape can be set.
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