| 摘要 |
<p>This invention relates to an image scanning apparatus and more particularly to the scanning apparatus for use in a digital copier which obtains a negative image from an image of an original. A color image signal is generated from an image sensor by sensing a reflected light from an original through a scanner and an optical filter, and is converted to an image data consisting of a color code and a luminance data. Color histograms and summarised histogram are produced from the image data, which represent luminance distributions for each color code and a total luminance distribution. A pattern class for each histogram is identified by checking histogram shape, and coefficient data of mutual transfer function and gamma data are selected from data tables according to the identified pattern class. The luminance data are corrected in accordance with the selected coefficient data and gamma data.</p> |
