JP2925043B

PURPOSE:To provide a picture of high quality by using a maximum value and a minimum value of gradations as a first reference value and a second reference value respectively and expanding and reproducing a picture having a middle gradation from the mixture proportion value of first and second reference values. CONSTITUTION:A background picture signal and a superimpose picture signal including characters and symbols are compressed or encoded independently of each other. Picture data of characters, shadow, or the like is expressed with plural gradations by a data converting means 112 and is handled as a multilevel picture. A maximum value and a minimum value of gradations are encoded to Huffman codes in a Huffman encoding part 116 by run length, and a middle value is encoded by assignment of a code or the like provided in the Huffman code system. In this case, the middle value of picture data on boundaries of characters, shadow, or the like is expressed as the mixture proportion (mixing value) of the maximum value of gradations (picture data of characters or the like as the first reference value) and the minimum value of gradations (background picture data as the second reference value).