Daniel V. Cusick - Chesterland OH Michael A. Chmura - Willoughby Hills OH Raymond G. Molnar - Boston Heights OH
Assignee:
Bell & Howell Publication Systems Company - Wooster OH
International Classification:
G06K 1500
US Classification:
395115
Abstract:
An image is stored in raster format having N raster or data lines each with M pixel values in an image or print buffer memory (10). An addressing circuit (20) addresses the print buffer memory to read out m. times. n bit columns or blocks of data, where n=N unless cropping of the image is desired. The blocks are parallel loaded alternately into a first FIFO memory array (40) and a second FIFO memory array (62). Each FIFO memory array includes a plurality of FIFO memories (42a-p 64a-p) which store n data lines segments each of m/p bits. In the first n clock cycles of the first FIFO memory (42a), a multiplexer (46) passes the least significant bit (50) of each data line segment read out of the first FIFO memory. The next N times that the first FIFO memory is clocked, the multiplexer passes the next least significant bit and so on until all m/p bits have been passed serially to a laser printer (48). Thereafter, this process is repeated for a second FIFO memory (42b) and each successive one of the p FIFO memories of the first array.
Daniel V. Cusick - Chesterland OH John E. Conroy - Hudson OH Raymond G. Molnar - Boston Heights OH O. Nolan Daines - Fremont CA
Assignee:
Bell & Howell Publication Systems, Company - Wooster OH
International Classification:
G09G 106
US Classification:
340723
Abstract:
An image having more pixels than can be displayed on a video monitor (16) is stored in an image buffer (10) in packed raster format. During a vertical retrace period, the video monitor generates several horizontal synchronization signals which clock a video memory controller (20). Each time the video memory controller is clocked, it moves a portion of a next successive row of data from the image buffer to a video memory (12). In this manner, several rows of new data are loaded into the video memory before the video monitor starts withdrawing data from the video memory to display the first raster scan line. As the raster scan line is indexed to move down the video image by the horizontal synchronization pulses, the same horizontal synchronization pulses continue to index the row addresses of the video memory controller keeping the transfer of new data into the video memory several lines ahead of the current raster scan line. In a panning mode, the vertical synchronization signal of the video monitor resets the video memory controller to a new initial starting address (26') shifted a small distance, e. g. one pixel from a preceding data transfer start address (26).