| 摘要 |
Shading is eliminated in an image read-out apparatus for scanning a light beam on a recording medium carrying an image recorded thereon, obtaining light which carries the image by the scanning, and detecting the light by use of a photomultiplier to obtain read-out signals carrying the image. A shading elimination method comprises the steps of detecting the shading characteristics in the direction of main scanning of the light beam by changing the level of high voltage applied to the photomultiplier to a plurality of levels prior to the detection of the light, and storing the shading characteristics to correspond to the levels of the high voltage in a memory. The level of the high voltage is detected at the time of the detection of the light, and the shading characteristics that correspond to the detected level of the high voltage are read from the memory. The read-out signals are corrected in accordance with the shading characteristics read from the memory so that changes in the output of the photomultiplier caused by the shading are eliminated. |
