| 摘要 |
PURPOSE:To reduce greately the degree of erroneous identification of pictures by obtaining a degenerated state from the multi-value coded data of each picture element and identifying whether the noticed picture elements are equal to a character/line drawing or a variable density drawing based on the degenerated states of the noticed picture elements and their reference picture elements and with reference to a maximum likelihood deciding table. CONSTITUTION:The multi-value coded data is obtained for each picture element by means of plural pieces of unit threshold value. Based on these data, the degenerated state is obtained for each block consisting of plural picture elements. Then a picture of the noticed picture elements is identified with a high degree with reference to a maximum likelihood deciding table obtained from the probability with which the state of a noticed block is produced from the state of the block produced previously and based on the degenerated states of both noticed and reference picture elements. In other words, a detecting system using the unit threshold value is used to identify every block of plural picture elements whether a picture in an original is equal to a character/line drawing or a variable density drawing in case both character/line and variable density drawings are mixed in the original. Then the block is identified as a variable density drawing and therefore binary coded with the threshold value of a dither matrix. While the block is binary coded with the single threshold value when it is identified as a character/line drawing respectively.
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