| 摘要 |
PURPOSE:To attain the expression of (n+1)<2> of gradation number by occupying n-set (number of cells in a block) of cells sequentially with a light dot attended with level change of a picture signal, adding one dark dot after all n-set of the cells are occupied by light dots, erasing the light dots and repeating the operation. CONSTITUTION:The order of arrangement of threshold values is arranged oppositely in a threshold matrix (Figs. A and B) for light and dark dots. Numerals in a recording dot pattern (Fig. C) to a signal level of an input picture element indicate signal levels or number of gradations. For example, the combination of picture element constitution with one picture element (3X3) by using two kinds of inks (dark/light) is as shown in the figure. In the figure. E indicates light ink dots, F depicts dark ink dots and G is dots being the superimposition of both the dots. In this case, the relation is set closely as Dd:Dl=n+1:1, where Dd is the reflected optical density when the light and dark dots are recorded in a uniform density respectively and Dl is the reflecting optical density when dots are recorded with the same density as that of the dark dots. Then the number of gradations expressed in using two kinds of dark/light inks and forming one picture element as lXm=n dots is (lXm+1)<2>, that is, (n+1)<2>. |
