Abstract: There is provided an improved image reader. In the image reader, light from an object is converted into an analog signal by a photoelectric converter. The signal is quantized by an A/D converter on the basis of top and bottom reference voltages to produce a digital picture signal. A digital picture signal corresponding to a dark current flowing to the photoelectric converter is stored in a memory as a dark current data. Also a digital picture signal corresponding to the optical strength of predetermined level is stored in another memory as a white level data. Then, the top and bottom reference voltages are produced which correspond to the top and bottom quantization-threshold values on the basis of the dark current and white level data, respectively. The top and bottom reference voltages are then respectively applied to the A/D converter to produce the digital picture signal without signal distortion.

Abstract: A frame of photographic film is optoelectronically scanned after development to produce an electronic image which is analayzed to determine the exposure and development conditions of the film. Tone conversion signals are generated in accordance with the analyzed conditions to convert the tone characteristics of the electronic image to optimal values and thereby compensate for non-standard exposure and development. The electronic image of the entire frame, or alternatively only a part of the electronic image corresponding to an unexposed area of the frame, may be used to determine the development conditions.