Using color management systems to adjust the ink Keys at the litho offset sheet feed printing machine Dr /

Using color management systems in order to obtain uniform color production along all stages of printing production which allows: Increasing the quality of the print production. Increasing quality consistency. Time/money savings in prepress through decreased retouching of images and remaking of proofs. Time/money savings in printing through faster color ok in makeready. The study is to find The impact of using color management systems which can be applied through all print production stages from prepress till the press stage. Adjusting ink zones on the printing machine is considered to be one of the most important factors that affect the quality of the printed color which can be an affecting factor in producing the dot gain phenomenon, and also decrease the print waste percentage. The research have been established through a number of experiments and measurements recorded in each of the extent of change.

There are even differences in the way individual printers of the same model manage color.Many variables affect color, including your ink and paper type.
Color Managementis a way to set up your environment (called a workflow) to allow all these devices to speak the same language so you can get accurate and predictable results.The ultimate goal is to match the colors of the image displayed on your monitor with the ones produced by your printer .(1) We use Color Management software to create profiles for all devices.A profile provides a description of each device's color gamutthe range of reproducible color.This diagram (FIGURE 1) represents the way we see and accurately indicates the uneven sensitivity we have to all of the colors.It's also convenient as we can count on this space to stay the same regardless of how it's viewed or imaged with any device.
In fact, because of the lack of dependence on any other factors we call it device-independent.
As more technologies evolved it became apparent that measurement systems and computers needed a better balance of information, so the spacing between colors was shaped to become more consistent and even.We call this space L*a*b*, or simply Lab (FIGURE 2).
Technically a* represents the red/green axis, b* represents the yellow/blue axis, and a straight line going right through the center corresponds to L or the lightness.
Lab is a great place for scientists, but it's also the space that's hidden in all of our computers.
So we're going to look at a few images the way our computers do.(3Monitor display VS Printing -The monitor produces the color you see on-screen with light while the printer produces color with pigment.The set of colors, or gamut, you can produce with light is not identical to the set you can produce with pigment.Thus there are colors you can produce on a monitor and not on a printer, and vice-versa. -The monitor uses three primary colors of light (red, green, blue) to produce all the colors you see on-screen.It mixes different amounts of each of the primaries to produce a particular color.An on-screen color is specified as three numeric values, the first describing the amount of red, the second the amount of green, and the third the amount of blue light to use to create the color.Thus these are often referred to as RGB (Red Blue Green) colors.
-The printer uses three primary colors of ink (cyan, magenta, yellow) and black to produce all the colors it prints.
-The set of colors you can produce with light (the RGB gamut) is larger than the set of colors you can produce with pigment (the CMYK gamut).Thus monitors can produce more colors than printers.There is a significant overlap between the two gamuts however, and, in those cases, the problem becomes how to match a color that it is possible to create with either light or pigment, on different physical devices.(4)

Representation and control of color in physical devices:
The difficulty with physical devices is that none are stable enough to ensure a consistent representation of a given color.Physical devices for our purposes are monitors and printers.
-Monitors The same color can vary across monitors due to factors such as the phosphor specification, the calibration, and the age of the individual monitor.Even on the same monitor the color can change as the monitor ages or loses its calibration.The set of colors a monitor can display (its gamut) can also vary across monitors.
-Printers The same color can also vary across printers or on the same printer due to factors such as the inks a printer uses, the amount of ink in the printer at the time you print, and the physical properties of the paper on which you print.The experiment: The researchers have printed the test shown in figure (3) first without using color management systems and then by using color management systems and they measured the impact of using the color management systems on the ink zones of the printing machine, dot gain range, printed dot size, L a b values, ink density, and then making comparison between the ISO values and the values before using color management systems and after using them and the results were as follows:

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Plates : Ipagsa CTP Thermal Plates Electra Excel 1030X790 mm -Developer : Ipagsa Thermal Plates Developer -Ink : Hartmann Lith -Blanket : Perfect Dot -Paper : Glossy Paper Class 1-135 gm Matt Paper Class 3-200 gm Machines: -Apple Mac Pro With Apple cinema Display 27 inch -Proofing Printer Plotter Epson 9800 -X-rite i1 For Calibration the Display and the Proofing Machineand make ICC profile for the Printer -CTP Heidelberg Supra Sitter VLF with interpolator HDX 125+ -RIP Unit Dell Power Adg 320 with prinect Prepress manager 2016 -Prinect Metashooter 2016 for the CTP control -Heidelberg CD102-5 With in press control -X-rite -Prinect Pressroom Manager 2016