okBalance is the optional extension level for the ColorPilot ink density control system from manroland sheetfed.
okBalance controls production after the defined OK sheet with priority on Color-/Gray Balance, considering tone value increases, tonality and solid ink densities as well. This achieves perfect color stability in print production.
The okBalance color control strategy is based on System Brunner Instrument Flight® technology and was specially developed for use with the manroland ColorPilot measuring systems.
The diagnosis module Print Consult® contained in okBalance runs in the background, compares the measured print results with the defined GLOBALSTANDARD®, indicates weaknesses in the printing process and suggests corrective actions if necessary to improve the printing results.
With okBalance 2.0, the software solution successful and proven for more than 10 years and with hundreds of installations worldwide is now provided with a number of new features:
Furthermore, okBalance 2.0 + G7® is available with display of the G7® characteristic values or this can be retrofitted. Thus with every measurement the printer can see whether the printing system also achieves the ND nominal target values and the ND actual values calculated by the G7® method for the “Tonality”as well as the gray balance a*/ b*. In the event of deviations, the printer makes a color correction, produces a new OK sheet, and production is kept constant with the okBalance control according to G7®.
The measurements are made using the okBalance print control strip v.1511, which also correspond with the maximum G7 specifications.
More than 80 percent of all color variations in four-color printing are caused by fluctuations of the halftone dots in the individual colors and in two- or three-color overprints. Studies made by System Brunner have shown that process variations that have an effect on Color Balance are most strongly noticeable by the observer. However, the measuring systems used today on printing presses mostly control only the solid ink density or the solid ink CIELAB the individual primary colors.
Because of the many variables in the printing process, the results with solid ink control are always different from job to job. By visual adjustment of inking feed, the printer finally achieves the accepted OK sheet.
But this is when the fun begins. Color variations can be seen within print production. And the customer expects the entire run to match the OK sheet, regardless of the process-inherent variations.
okBalance achieves this. okBalance controls color in the print production just like the printer perceives color deviations. But even more precisely and reliably. With okBalance, the color results can also be kept constant when visually or in individual zones deviations from standard are indicated.
If the color magenta for instance changes through a temperature increase or changes to the fountain solution feed during the run so that tone value increase rises, a red cast appears in the image (1). In the Hexagon diagram, this change is indicated in that the quadratic symbol for the color balance shifts in the magenta direction and the tone value increase for magenta rises. Solid ink density color control does not detect this because the solid tone inking has not changed. Accordingly, no deviation to the nominal densities is displayed and the printer has to intervene manually.
okBalance regulates the color cast back to the defined gray balance and thereby the appearance of the image also corresponds with the OK sheet (2). Through the process diagnosis the printer sees that the fountain solution feed needs to be checked.
okBalance is easy to operate and helps the printer, under practical conditions to keep the image contents as constant as possible during the run – a decisive feature because other systems can measure many things but only control based on solid ink density.
Just like solid ink density control, the color control software compensates for deviations to the OK sheet by opening or closing the ink slides. But as opposed to solid ink density control, the calculated ink slide position results primarily from the deviations of the overprinted color balances of the process colors CMY and the tone value increases. The solid ink densities of the individual colors CMYK are also taken into account but handled with a lower priority.
Through acquisition of the data for the process colors CMYK and controlling them according to gray balance, tonal values and solid tones, results are achieved that are much more compliant with human color perception than results from solid ink density color control alone. The priority on color/gray balance controls precisely the influencing variables that have the greatest effect on color variations in halftone printing.