| 摘要 |
PURPOSE:To enable encoding with little image quality deterioration within preset values of the numbers of code transmitted in encoding scanning units, by varying the number of codes of the 2nd mode block depending on the number of 1st mode blocks generated. CONSTITUTION:The quantization image signal 250 of Q bits attainable in the image reading device, after having been stored in the image memory 201 is read out by one picture element in block units. The picture element signal 260 is selected by a selector 202 and inputted in a adder-divider 203 and at the same stored in a memory 205 for one block. The average value 262 is calculated in a single block by the adder-divider 203 and outputted from a selector 204. The differences between this average value and the respective picture elements are taken and the absolute value is compared with the constant K and outputted to a deciding device 209. The deciding device 209 in accordance with the number of picture elements whose absolute value are larger than the foregoing constant K, separates between the 1st and 2nd mode blocks and according to the respective blocks, an encoder 215 carries out encoding.
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