Abstract: An image reader in which a plurality of light-sensitive cells arranged in an array in a line image sensor are divided into a predetermined number of blocks, and the blocks are sequentially selected to sequentially drive the light-sensitive cells in each of the blocks to produce image signals. Charging switches are provided for charging the light-sensitive cells via block selector switches. The charging switches are activated after a signal read time assigned to each light-sensitive cell has expired to thereby shorten the charging time necessary for the light-sensitive cell. The block selector switches are each actuated at a predetermined timing while the charging switches are activated, thereby preventing noise due to switching actions of the block selector switches from being introduced into image signals.

Abstract: A halftone processing method for a digital facsimile apparatus utilizing the dither method is disclosed which permits a threshold level to be changed at every desired number of picture elements in the horizontal scan direction. The change of the threshold level may occur selectively at every other picture element, every two picture elements every three picture elements and every four picture elements.