by the line segment emphasis filter 7 in the first line segment emphasis filtering for example filtering processing represented by filter coefficients shown in fig3 is performed to emphasize line segments of directions of u00b1 45 degrees the first emphasis image data obtained by the first line segment emphasis filtering is stored into the first buffer memory 8 here the line segment emphasis filter is described an operation of emphasizing an edge of a picture which is low in contrast and provides a dull feeling by filtering to make the picture clear cut is generally called sharpening processing sharpening can be realized by emphasizing high frequency components in a spatial frequency distribution of the image data i e picture fig4 a to 4c are views illustrating sharpening processing and in fig4 a to 4c the axis of abscissa represents the pixel position and the axis of ordinate represents the pixel value when a line is given as an original image data as shown in fig4 a if a laplacean filter which is a two dimensional spatial differential linear filter is performed for the original image data then a laplacean image data having such a pixel value distribution as shown in fig4 b is obtained then if the laplacean image data shown in fig4 b is subtracted from the original image data shown in fig4 a then since the pixel values at rising portions of the edge decrease while the pixel values at shoulder portions of the edge increase the edge is emphasized as shown in fig4 c the filtering processing wherein processing.