| 摘要 |
PURPOSE: To judge whether or not high frequency halftone image data are present by using the approximation function of an automatic correlation function using a logic function and addition and detecting a peak in a function for which an automatic correlation function processing is performed. CONSTITUTION: The flow of pixels taken out from a data buffer 20 enters automatic correlation device constitution and is turned to the function of the complement of 2 by a logic device 100 and the function -f (1) of the complement of 2 and respective delay signals f(1+k3 ,) f(1+k4 ,) f(1+k5 ) and f(1+k6 ) selected as the ones for indicating the pixels in signals are added with each other in adders 104-1 to 104-4. When the accumulation of the blocks of the pixels is completed, a value is transferred to comparators 110-1 to 110-4 and the comparators compare adjacent samples and decide a minimum value. By the detection of the minimum value, output meaning high frequency halftone information is generated at an OR gate 118. |
