Display system comprising a windowing mechanism
First Claim
1. A display system comprising a palette for picture chrominance and/or luminance information, a display buffer for pixel information defining the pixels of a display field, the pixel information including index values for indexing the palette to select the chrominance and/or luminance of the pixels, and a windowing mechanism for associating a different range of index values with each of a plurality of windows wherein each window may have a visible extent area in the display buffer, and wherein the windowing mechanism controls display buffer update by determining the visible extent of a given window in the display buffer in response to index values stored at individual pixel positions in the display buffer.
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Accused Products
Abstract
In a display system having a palette for chrominance and/or luminance information, a display buffer for information defining the pixels of a display field, including index values for indexing the palette select the chrominance and/or luminance of the pixels, a windowing mechanism is provided for associating a different range of index values with each of a plurality of windows and for responding to index values stored at individual pixel positions in the display buffer to determine the visible extent of a given window within the display field. This allows a plurality of windows to be displayed with a minimum of extra logic and without unduly constraining the choice of colors available within those windows. In the described embodiment, windows are defined in a first phase by storing index values from the range of values associated with that window at all pixel positions for that window. Then, in a second phase, the output of a range comparator for comparing index values stored in the display buffer to the range of values associated with a given window is used to control multiplexer means to cause an item of update information destined for a particular pixel position to be stored at that pixel position in the display buffer only if the comparison is positive.
51 Citations
19 Claims
- 1. A display system comprising a palette for picture chrominance and/or luminance information, a display buffer for pixel information defining the pixels of a display field, the pixel information including index values for indexing the palette to select the chrominance and/or luminance of the pixels, and a windowing mechanism for associating a different range of index values with each of a plurality of windows wherein each window may have a visible extent area in the display buffer, and wherein the windowing mechanism controls display buffer update by determining the visible extent of a given window in the display buffer in response to index values stored at individual pixel positions in the display buffer.
- 14. A display buffering system comprising a display buffer for pixel information defining the pixels of a display field, a windowing mechanism for associating a different range of pixel values with each of a plurality of windows wherein each window may have a visible extent area in the display buffer, and wherein the windowing mechanism controls display buffer update by determining the visible extent of a given window in the display buffer in response to values stored at individual pixel positions in the display buffer.
- 17. A display buffering system comprising a display buffer for pixel information defining the pixels of a display field, a windowing mechanism for associating a different range of pixel values with each of a plurality of windows wherein each window may have a visible extent area in the display buffer, and display buffer update inhibit means inhibiting the update of pixel information in the display buffer for pixels outside the visible extent of a given window within the display field, the inhibit means responsive to values stored at individual pixel positions in the display buffer.
Specification