Method and apparatus for displaying higher color resolution on a hand-held LCD device

• US 6,369,827 B1
• Filed: 08/04/2000
• Issued: 04/09/2002
• Est. Priority Date: 11/24/1999
• Status: Expired due to Term

• Current Assignee: Nintendo Company Limited
• Original Assignee: Nintendo Company Limited
• Inventors: Li, Xin, Fam, Sun Tjen, Comair, Claude, Champagne, Robert, Pan, Jun, Ghali, Prasanna, Abou-Samra, Samir
• Primary Examiner(s): Luu, Matthew
• Application Number:
  US09/633,357
• Time in Patent Office: 613 Days
• Field of Search: 345/152, 345/153, 345/132, 345/149, 345/88, 345/199, 345/3.2, 345/3.3, 273/148.B, 463/45
• US Class Current: 345/591
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: G09G 5/02 characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607
• CPC Class Codes: G09G 5/06 using colour palettes, e.g. look-up tables

Abstract

Effective color resolution of a limited-memory color-mapped display system such as a portable liquid crystal display (LCD) handheld video game system can be increased by changing the color mapping information during active display time (e.g., during the horizontal blanking interval between rasterization of successive lines on the display). A subset of the color mapping information can be rewritten during each horizontal blanking period. A full color bitmapped source image can be converted into a color-mapped image in a way that optimizes the use of such color map updates. Since photographic and photorealistic images typically don'"'"'t exhibit abrupt color changes between neighboring pixels, such techniques can result in display of a color image with very high color resolution (e.g., having as many as 2048 different colors) on hardware intended to permit simultaneous display of only a much smaller number of different colors (e.g., only 56 different colors simultaneously).

Claims

1. A memory cartridge for color-mapped display system that uses color mapping data to generate a color image on a color display during active line scanning, said display system comprising a color display and image generating circuitry that generates an image on said display during active line scanning based at least in part on color mapping data stored in a color map, said memory cartridge including a non-volatile memory that stores a data updating routine for updating said stored color mapping data during said active line scanning so as to increase the effective color resolution of said system.

2. A memory cartridge as in claim 1 wherein said image generating circuitry periodically generates a horizontal blanking interval, and said data updating routine controls said system to update said stored color mapping data during said horizontal blanking interval.

3. A memory cartridge as in claim 1 wherein said data updating routine controls said system to update only a portion of said color mapping data during each horizontal blanking interval.

4. A memory cartridge as in claim 1 wherein said data updating routine controls said system to update half of said color mapping data during each horizontal blanking interval.

5. A memory cartridge as in claim 1 wherein said data updating routine controls said system to copy four new color palettes each providing four colors into said color map every 108.7 microseconds.

6. A memory cartridge as in claim 1 wherein said data updating routine includes a POP instruction for retrieving color mapping data for copying into said color map.

7. A memory cartridge as in claim 1 wherein said image generator performs character-mapping, and said data updating routine controls said system to updates said color mapping data in synchronism with said character mapping.

8. A memory cartridge as in claim 1 wherein said color display has a predetermined display area, and said data updating routine controls said system to update color mapping data for only a subset of said predetermined display area.

9. A memory cartridge as in claim 1 wherein said image generator is character-mapped, and said data updating routine controls said character-mapped image generator to display near-photographic quality images on said display.

10. A memory cartridge as in claim 1 wherein said display system is designed to display N colors in a single display frame on said display, and said data updating routine permits said display system to display more than 30×

N colors in a single display frame on said display.

11. In a handheld portable game system including a raster-scanned color liquid crystal display that displays lines of pixels within a frame time, horizontal blanking intervals occurring between display of successive ones of said lines of pixels, said system further including color mapping display circuitry that color maps graphics information for display based on a stored color map comprising plural color palettes, a color map updating and display process performed in real time within said frame time comprising:

(a) writing at least one color palette to said color map during a horizontal blanking interval;

(b) displaying at least one line of pixels based on said at least one color palette written by said step (a) and at least one color palette previously stored within said color map;

(c) writing at least one further color palette to said color map during at least one further horizontal blanking interval; and

(d) display at least one further line of pixels based on the combination of said color palettes written by said steps (a) and (c).

12. A process as in claim 11 wherein step (a) is performed during a horizontal blanking interval immediately preceding said line displayed by step (b), and step (c) is performed during a horizontal blanking interval immediately following said line displayed by step (b) and immediately preceding said line displayed by step (d).

13. A process as in claim 11 wherein step (a) writes half of a set of eight color palettes, and step (c) writes the other half of said set of eight color palettes.

14. A process as in claim 11 wherein step (b) displays a maximum of half of said line based on said color palettes written by step (a), and step (d) displays all of said further line based on color palettes written by steps (a) and (c).

15. A process as in claim 11 wherein steps (a) and (c) together rewrite all background color palettes within said color map over two successive horizontal blanking intervals.

16. A process as in claim 11 wherein steps (a) and (c) together rewrite eight background color palettes within said color map over two successive horizontal blanking intervals.