| 摘要 |
<p>A digital copying apparatus with an adjustable reproduction characteristic, wherein the reproduction characteristic describes a mapping of optical densities of an original document, hereinafter referred to as: ODin, on optical densities of a copy of the said original document, made by the apparatus, hereinafter referred to as ODout. The apparatus comprises an operating unit with means for setting a required reproduction characteristic, a generator for generating first digital image data corresponding to an image on an original document, a printing unit for making a print on an image support on the basis of second digital image data, a processing unit for converting said first digital image data into the said second digital image data in accordance with a reproduction characteristic set by the operating unit. In principle, the processing unit converts the said first digital image data into the said second digital image data in accordance with a reproduction characteristic which comprises a first part, which maps on white, a second part which maps on density values between white and black, and a third part, which maps on black, which parts merge into one another in a first and second shoulder point (A, B) respectively. Adjustability of the reproduction characteristic is obtained by setting the ODin value of one or both shoulder points by means of the operating means. The invention also applies to changing the contrast in colour copying, in which case the parameter for adjusting the reproduction characteristic is the luminance comprised in the digital image data. <IMAGE></p> |
