On the ink supply control panel, each row of lights represents a certain position on the ink roller and therefore also a section of the image. Flashing lights mean the ink quantities are being adjusted. The printer must fine-tune the settings manually and can adjust the ink feed for each separate section.
Printing plate make up
Once the ink is set up, the plates are mounted on each colour unit, either by
hand or automatically. Extreme care is needed because even small scratches on the plates would be visible in the printed image. The plates must all be in accurate register so that the image of each separate colour will be in exactly the same position on the sheet. Every plate has register holes to locate it precisely and consistently on both the machines where it is first made and then on the printing press. This ensure es accurate register on the press.
The press is now ready to produce the first print and the printer immediately starts making colour and register corrections. He keeps on correcting and adjusting until the desired optimal printing result is achieved.
To correct an image where the colours are far apart, the printer uses the so-called register marks, for correcting the plate positions until the register marks appear correctly.
After adjustment, the colours are printed in exactly the same position and the picture becomes clear.