SHADING CORRECTION METHOD FOR PICTURE INFORMATION READER

摘要

PURPOSE:To eliminate the streaky shading by giving the digital correction to a digitized read signal in accordance with the shading characteristics of a condenser and also adding the random component to the read signal. CONSTITUTION:When the radiation picture information recorded to a storage type fluorescent sheet 10 is read out, a digital read signal Sd is delivered through a shading correcting circuit 24. The circuit 24 reads the correction value out of a memory 31 and subtracts the correction value Un from the signal Sd related to the picture elements of the n-th column. At the same time, the circuit 24 performs correction to add the random component F produced by a random producing circuit 32 to each picture element for the signals Sd of all picture elements. Thus the overs/shorts of the value Un are not produced regularly in the main scan direction of beam owing to addition of the component F even in case the value Un has overs/shorts compared with the proper value due to the shortage of the bit resolution. This eliminates the uneveness of density which is extended in the secondary scan direction Y.