Patent ID: 8922671

Claim:
A method of compression programmed in a controller of a device comprising: a. partitioning an image into one or more blocks; and b. encoding the one or more blocks using a natural mode or a 4-color graphics mode, wherein the graphics mode includes: i. computing a first threshold; ii. grouping sample values less than or equal to the first threshold in a first primary group; iii. grouping the sample values greater than the first threshold in a second primary group; iv. computing a second threshold and a third threshold; v. grouping the sample values in the first primary group less than or equal to the second threshold in a first secondary group; vi. grouping the sample values in the first primary group greater than the second threshold in a second secondary group; vii. grouping the sample values in the second primary group less than or equal to the third threshold in a third secondary group; and viii. grouping the sample values in the second primary group greater than the third threshold in a fourth secondary group.