| 摘要 |
PURPOSE:To increase the number of display gradations without receiving any limit of image resolution ratio between an input and output by using a means which defines several picture elements of a picture as one block and expanding the picture into a density pattern for each block for display of gradation. CONSTITUTION:Picture data having gradations and inputted from an input device 1 is converted into digital gradation signals of 4 bits, for example, for each picture element by an A/D converter 2. These gradation signals are stored in a picture memory 3. In case multilevel data stored in the memory 3 is intermediately displayed in a binary values of black and white, only 16 gradations (4X4) are shown as long as the output side has (4X4) image resolution, for example, with respect to the image resolution of the input side. In this case, four picture elements which approximate the multilevel data on the memory 3 are put in one group to show 64 gradations (8X8). Thus it is possible to increase the number of gradations to be displayed without receiving any limit of the image resolution ratio between the input and the output.
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