What is offset printing

What is offset printing?


Offset printing for several decades was the only way to print a color image on paper. Currently there are several methods of printing color images. For large circulations, offset printing remains, however, the best option as price and quality.

Offset printing process involves the transfer of liquid ink on the printing plate on an intermediate surface (such as a rubber cylinder) and then on the final support (paper). To obtain printing plates is needed the color separation contained in an image. How to get color by printing?

When it comes to 4 color printing, this process refers to the colors Cyan, Magenta, Yellow (yellow) and Black (black). This color system known as CMYK shortening. By combining these colors, a wide range of colors can be produced on the printed page.

If the colors are combined on paper (they are printed as small dots, some partial overlayed, on rasterization principle – Halftoning), the human eye combining the colors to see the final image.

What is color separation?

Color separation is a process by which a digital document is separated into individual components for color printing. Components are those mentioned above, Cyan, Magenta, Yellow and Black if it’s about the 4 color process, there also being the option of 6 colors. In this process, each color is applied to a printing plate.

The plates are used to combine color separation process called printing paper. For printing with laser printers or inkjet the process is similar, but transfer printing plates are no longer used.

In the printing process of color separation, each color used in a separate document in the 4 primary colors, CMYK, each color plane having an angle. Each of the primary colors is transposed on a printing plate used then to print. Such a plate (eg Cyan) contains all graphic elements of the page that have the primary color (for example, Cyan) of various hues.

Color separations, is done digital according to the software used for editing, the one of printer RIP (printer that performs printing film) or the CTP’s software computer to plate – made directly printing plates, eliminating the need for film).

There is no need to perform color separation yourselves. In general the document is sent to printing or DTP office, and they will realize the steps leading up the printing process, including color separation.

To print can be made digital documents that contain composite separations (all color information in a single file) or pre-separated (each primary color in CMYK, on its own page).
Below you can see starting from the left: original image CMYK, Cyan plan, Magenta plan, Yellow and Black plan.

4 color printing process (full color)

For this color printing process use primary colors, subtractive: Cyan, Magenta, Yellow and Black. CMYK process is the most widely used printing process, both offset (printing) and digital (printers, plotters).

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