Patent ID: 7336302

Claim:
A frame memory device which sequentially receives raster-scanned digital color image signals, and sequentially stores the image signals in a memory having a two-dimensional address structure, such that vertical addresses represent the order of entry of respective scan lines that constitute said image signals and horizontal addresses represent the order of entry of respective signals that belong to each of the scan lines, and which sequentially reads out the stored signals from said memory so as to output the signals again as raster-scanned signals, said frame memory device being characterized by comprising: signal rearranging means for rearranging the order of received signals to be stored in said memory; and subsampling and read-out means for reading out stored signals while skipping horizontal and vertical addresses of said memory at regular intervals, whereby the stored image signals that are subsampled are read out from said memory so as to output raster-scanned image signals at lower resolution than that of the received image signals, wherein the received image signals comprise YC B C R color signals having a sampling ratio of 4:2:2, in which the number of horizontal pixels of C B and C R signals is equal to one half that of Y signals, and wherein the Y signals and the C B and C R signals are input and output in parallel with each other from a Y bus and a C bus, respectively, and the Y signals and C B and C R signals of a frame of said image signals are written into and read out from a Y memory and a C memory, respectively, constituting said memory, with the Y and C signals transmitted in parallel with each other, said C B and C R signals being multiplexed at alternate pixels and input and output from the C bus in the order of C B →C R , and being characterized in that: said signal rearranging means rearranges the C B and C R signals in the order of C B →C B →C R →C R to alternate the signals at every other pixel, and the C B and C R signals rearranged by said means are synchronized with the Y signals so that the Y and C signals are respectively written into said Y memory and said C memory in parallel with each other, and in that said subsampling and read-out means accesses alternate ones of horizontal and vertical addresses of said Y memory and C memory to read out the Y and C signals in parallel with each other, thereby to output raster-scanned YC B C R image signals that have been subsampled to one half in both horizontal and vertical directions by said subsampling and read-out means.