| 摘要 |
The circuit is for decribing black and white image by pseudo 64 gray level using 4-bit analog to digital converters. The circuit includes a pre-processor unit (20) for quantizing analog image signal by 16-level and converting the quantized signal into digital signal by comparing the quantized signal with 64 gray level dither matrix, a direct memory access circuit (40) for storing the digital image signal on a special memory region of a main memory by direct memory access, an auxiliary memory (80) for storing upper 4-bit of digital image signal, a first buffer (90) for sending digital image signal by combining upper 4-bit and lower 4-bit, a control logic unit (60) for generating R/W signal of main memory, enable signal of the first buffer and an OR gate (70) for generating write enable signal for the main memory.
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