Abstract: Accurate on-line color control for a printing press can be obtained using intra-image color control. A concurrent spectrophotometer and imaging system can capture spectral reflectance data from predetermined measurement areas for each ink key zone of the press. The spectral reflectance data can be compared to target reflectance values in the same standard color space, and a determination can be made as to whether the differences between the measured and target values exceed predetermined tolerances. If the differences exceed these tolerances, a necessary adjustment to the appropriate ink key can be calculated to bring the color differences back to within tolerance. This approach is particularly beneficial in web offset printing, where the printed image is constantly moving and the press conditions are particularly variable.

Abstract: When a color-difference exceeds an established color tolerance, spectral reflectance values of a test area are converted to colorimetric densities and compared with target colorimetric density values for the corresponding test area from which a colorimetric density difference is established. The colorimetric density difference is utilized to determine an ink correction value.

Abstract: A method for controlling color on press during printing utilizing spectral measurements is disclosed. When a color-difference is exceeded the measured spectral reflectance values of a test area are compared with the corresponding target reflectance values from which a spectral reflectance difference is established. A linear equation is used to relate the spectral reflectance difference to solid ink density or ink layer thickness differences for ink regulation utilizing an on-line empirically established correction matrix such that the spectral reflectance difference is minimized. The control method is applicable to both process and non-process colors.

Abstract: When a color-difference exceeds an established color tolerance, spectral reflectance values of a test area are converted to colorimetric densities and compared with target colorimetric density values for the corresponding test area from which a colorimetric density difference is established. The colorimetric density difference is utilized to determine an ink correction value.

Abstract: A method for controlling color on press during printing utilizing spectral measurements is disclosed. When a color-difference is exceeded the measured spectral reflectance values of a test area are compared with the corresponding target reflectance values from which a spectral reflectance difference is established. A linear equation is used to relate the spectral reflectance difference to solid ink density or ink layer thickness differences for ink regulation utilizing an on-line empirically established correction matrix such that the spectral reflectance difference is minimized. The control method is applicable to both process and non-process colors.