A character compaction and generation method and apparatus which is particularly adapted to the compaction and generation of complex characters such as Kanji characters. Each character in a complex character set is defined by an I row and J column dot matrix, wherein each row is comprised of J bytes. Each successive row of a given character is scanned from the first through the Jth byte to determine if the current byte being scanned has the same numerical value as the immediately preceding or directly above byte in the scanning sequence. The number of successively read out sequence of bytes that have the same numerical value as the immediately preceding or directly above byte are coded as single symbols words Pn and Am, respectively, where n and m are integers which are indicative of the number of successive bytes scanned in sequence which are equal in numerical value to each immediately preceding or directly above byte. If a current byte being scanned is not of the same numerical value as the previous byte or the above byte, it is coded as a single symbol Sx, where x is an integer which is indicative of its numerical value. Each of the successively generated symbols Pn, Am and Sx for a given complex character are stored as a compacted complex representation thereof.
A method and apparatus for generating a compressed representation of a two-dimensional image where the image is described as a sequence of pixels in raster order. The method includes receiving the two-dimensional image as a sequence of pixels in raster order. For each pixel, the system determines whether the pixel is part of a first string of pixels that is identical to a second string of pixels found previously in the image at one of a plurality of preselected fixed distances from the first string of pixels. If so, the first string of pixels is encoded as a string token that is a reference to the second string of pixels. Otherwise, the pixel is encoded as a non-string token.
A method and apparatus for generating a compressed representation of a two-dimensional image where the image is described as a sequence of pixels in raster order. The method includes receiving the two-dimensional image as a sequence of pixels in raster order. For each pixel, the system determines whether the pixel is part of a first string of pixels that is identical to a second string of pixels found previously in the image at one of a plurality of preselected fixed distances from the first string of pixels. If so, the first string of pixels is encoded as a string token that is a reference to the second string of pixels. Otherwise, the pixel is encoded as a non-string token.
A font data compression method in a character generator is disclosed. The character generator stores bit patterns for forming a part of dot matrix data based on a specific rule applied to a plurality of font pattern. During regeneration of the font patterns, a whole configuration of the font patterns is automatically regenerated based on the bit patterns for forming a part of the dot matrix data based on the specific rule which have been stored in the character generator.
The invented data compression/decompression methods, device, and resulting data structures, operate by noting likenesses and differences between portions of data, and effecting data storage only with respect to the noted differences. The compression method arranges the data, compares portions of the data, and provides a flag to signal changes between adjacent data portions. The decompression method reads a portion of data, identifies whether the flag signals any changes in the data, and if so, reads a subsequent portion of data; but if no changes are signaled, then the first portion of data is duplicated. The invented device includes memory, a structure for storing data in the memory, data stored in the memory with flags to signal changes in the data, and structure for accessing and using the stored data. The invented data structure includes data divided into predetermined sections, and flags associated with the sections to signal changes within the sections.
The present invention discloses a method and apparatus for performing data compression during monitor refresh operations. In one embodiment, it is envisioned that the compression functions would be performed in a refresh compaction device and the de-compression functions would be performed in a RAMDAC, thereby requiring only the transfer of compressed data between the refresh compaction device and the RAMDAC. In an alternative embodiment, it is envisioned that both the compression and de-compression functions would be performed in the refresh compaction device. Regardless of implementation, a "critical fill" level is determined during compression and a "critical fill" interrupt is generated during de-compression to gain control of the frame buffer before the compressed digital data is fully depleted.
