Shading correction device

DETAILED DESCRIPTION Accordingly, the present invention has been made to overcome the above-noted problem involved in the prior art and is directed to provide a shading correction device to assure a high reproducibility in picture signal processing at the original reader.
The shading correction device according to the present invention eliminates the unevenness of the signal level by subjecting the picture signal after the photoelectric conversion to automatic shading correction.
In order to achieve the above object, in the shade correction device of the present invention a variable attenuator is provided in the path of the photoelectrically converted picture signal, data on how much attenuation is required to make the level of each picture element uniform is generated for each picture element while the level of each bit of the picture signal, i.
e.
, the level of each picture signal is lowered at the time of scanning on total white surface of the original in the initial stage of original scan, the data is stored in a memory, and at the time of reading the original in subsequent scan the variable attenuator is driven and controlled based on the data stored in the memory.
In this manner, the picture signal is subjected to the shading correction for all picture elements one by one and transferred to the subsequent stage as a highly reliable signal for image reproduction.