TW277196B - Color scanner - Google Patents

Abstract

A color scanner which can modulate the level of continuous level of a original color pattern by the level modulation portion of the color scanner, such that to produce a mid-level color copied pattern. This level modulation portion comprises of (1) Use the function of recorded medium characteristic curve of the color original pattern, from its density (D) to find out its lightness (x). In this characteristic curve, the D-x coordinate system are used to specify the relationship between the lightness (x) project on the recorded medium and the density (D) form on the recorded medium; (2) Use the function of the following modulation formula to modulate the lightness value (x) into brightness value (yn); and (3) Color level modulation function which include: (3)-1. Set a color level managing point (M1) in the position between the brightest part (H) and darkest part (S) of the original color pattern, to manage the color level of the color printed pattern; (3)-2. On the color level managing point (M1), the color level modulating criteria is decided by the brightness of the color plate's level (C,M,Y,BL); (3)-3. Substitute the lightness value of M1, brightness of the color plate and the brightness of H and S to the following level modulation formula to get the (gamma); prepare the level modulation formula to change the pixel lightness value of the H and S part of color plate to the level brightness value (yn); and (3)-4. Using the formula with the (gamma) value to change the pixel lightness, and modulate & manage the color level. The level modulation formula is: yn=yH+[(alpha)(1-10-kx)(yS-yH)/(alpha-beta)] Here X: is equal to (xn-xH), which means the relative lightness (xn) to the density of a pixel in the original color pattern subtract the relative lightness (xH) to the density of the H part in the same pattern to get the basis lightness value; yn: Level brightness of the pixel (n) on the color copied pattern;yH: Preset level brightness of the H part for the color copied pattern; yS: Preset level brightness of the S part for the color copied pattern; (alpha): Surface reflection rate of the pattern appearance medium for recording the color copied pattern; (beta): Decided by (beta)=10-(gamma); K: Decided by k=(gamma)/(xS-xH). Here, xS is the relative lightness of the S part for original color pattern; (gamma): Arbitrary coefficient.