US 4,561,016 A · Method and apparatus for recording color pictures for multicolor printing

Abstract

Method and apparatus for recording color pictures wherein color proofs are made before the actual printing for quality control in multicolor printing processes. The color pictures are exposed on a chromatic material wherein the exposed colors must coincide with the colors which are later to be printed on paper. So as to achieve the color equivalent color picture exposure, the required color density values for the chromatic material of the selected printed and exposed colors are identified with a visual or mensurational comparison of the CIE coordinates. The identified color density values for the exposed colors are allocated to the corresponding color separation values of the colors to be printed and during recording the allocated color density values are utilized instead of the color separation values and are converted into signals for driving a color exposure unit for example a proof recorder.

Claims23

Dependent claims

A method for producing color pictures which are used for quality control in multicolor printing by means of exposing chromatic photographic material such as paper or film with chromatic light, whereby the colors produced on the chromatic photographic material by exposure coincide with the colors to be printed on a print medium, characterized in that, the following steps are accomplished:

(a) before recording the color picture identifying the color density values for the photographic chromatic material required for a color-equivalent recording by mensurational or visual comparison of printed and exposed colors;
(b) using the color separation values of the color which are to be printed and the corresponding color density values during the recording of the color picture;
(c) determining the allocated color density values instead of the color separation values and converting the color density values into drive values for a color exposure unit.

An apparatus for exposing color pictures on chromatic material with light having a specific spectral distribution for quality control in multi-color printing processes comprising:

(a) a drive circuit (12) for generating drive values (r, g, b) from color separation values (Y, M, C, K), said drive circuit consisting of:
(a.sub.1) a color converter (16) which receives the color separation values and generates color density values (D.sub.Y, D.sub.M, D.sub.C) from the color separation values, and the color density values are a measure of the color densities for the chromatic material required for color-equivalent color picture exposure;
(a.sub.2) a linearization stage (17) which receives the output of the color converter (16) and provides color density linearization of the chromatic material;
and
(a.sub.3) a digital-to-analog converter (18) which receives the output of the linearization stage (17) and converts the color density values modified by the color density linearization into drive value signals;
and
(b) a color exposure unit (13) which is connected to the drive circuit (12) and which consists of:
(b.sub.1) at least one light source (32;
33;
34) for generating light having three spectral components;
(b.sub.2) light modulators (38, 39, 40) which are disposed in the light path and receives the drive value signals in order to alter the intensities of the three spectral components as a function of the drive value signals;
(b.sub.3) optical means (56;
57;
58;
60) for focusing the light on the chromatic material (11);
and
(c) a recording support (14) carrying the chromatic material (11) and movable relative to the color exposure unit (13).

14 more elements

Dependencies are inferred from the claim text.

Method and apparatus for recording color pictures for multicolor printing

Life of this patent

Method and apparatus for recording color pictures for multicolor printing

Life of this patent

Abstract

Claims23