An image data control system for use in an image reading equipment, in which analog signals output from a line sensor, which represent the amounts of light reflected from an original sheet are converted into digital signals by analog/digital conversion, and then the digital signals are converted into density signals to obtain original sheet reading signals in the form of the density signals, the system characterized in that offset control are performed by an offset control circuit and dark time output adjustment by the unit of picture elements are performed by a dark time correction circuit, respectively, after performing gain control by a gain control circuit.