IMAGE READER

PURPOSE:To eliminate unstability in an analog logarithm converter used for convensional density conversion and to reduce noise generated in a dark part of an image at the time of density conversion in an image reader for a scanner to be used for printing or image reading of electronic publication. CONSTITUTION:An image reading signal is amplified to a required level by an amplifier 104 and then A/D-converted by an A/D converter 105. An output from the A/D converter 105 is judged by a level judging device 107 and the output of the converter 105 is selectively filtered by a filter 106 in accordance with the judged result. Then non-linear conversion such as density conversion is executed by an LUT 109 and the reading signal is outputted from an interface 110 to an external equipment. This constitution makes it possible to execute scanner signal processing capable of removing unstability in a convensional analog logarithm amplifier and selectively reducing the increment of noise due to non-linear conversion such as density conversion.