IMAGE READER

PURPOSE:To share a storage means used for a digital filter for image edge emphasis processing and a storage means used for correcting the sensitivity of the optical detection element of an image pickup element. CONSTITUTION:Reflected light from a plain reference original 17 is converted into an image signal in a primary image pickup element 14, is digital-converted in an A/D converter 18 and is written into the storage circuit 28 through a multiplier 23. A micro processor 26 calculates sensitivity correction coefficients for respective optical detection elements in the one-dimensional image pickup element 14 from the content of the storage circuit 28 and sets them in a shift register 25. At the time of reading a general original 12, the multiplier 23 multiplies a read image element data by the respective sensitivity correction coefficients in the shift register 25 and the sensitivity of the respective optical detection elements is corrected. Then, data are written into the storage circuit 28 and are inputted to an image element, average circuit 27. The output of the image element average circuit 27 is subtracted from image data which are sequentially read from the storage circuit 28 in a subtracter 29 so as to emphasize an image edge.