Image Number 6 for United States Patent #6313850.
In a display system having a predefined number, n, of pixel types, a display processor, such as a digital versatile disc (DVD) display processor, includes a color palette which can store more than n color/contrast values and a subpicture bitmap composed of subpicture pixel values, each of which corresponds to one of the n pixel types. In a DVD display system, for example, the DVD subpicture pixel types are: Background, Pattern, Emphasis 1, and Emphasis 2. Each subpicture pixel value is, in turn, related to a color/contrast combination by the color palette, with each pixel value corresponding to the address of a palette location. The corresponding palette location contains the color/contrast value for the related subpicture pixel type. To modify the color/contrast value of a selected group of the pixels having one of the four DVD subpicture pixel types, the display processor updates the color palette, associating new color/contrast values with previously "unused" palette locations. Additionally, pixel values within the bitmap locations which are to have their color/contrast values changed are modified to correspond to the address of the color palette location containing the "new" color/contrast value. The display processor sends the updated color palette and bitmap to a video processor which combines the color palette information, bitmap information and video information to create a subpicture display which reflects the updated color/contrast values.