2-color printing of OMR sheets was necessary in the old OMR technology. In some softwares based on old technology, it is still necessary.
BUT in the new technology Addmen OMR Sheet Software, 2-color printing is not necessary. You can print black and white OMR Sheets on your laser printer of photocopy machine or on single black color offset printing.
Still, some organizations insist on the use of colored sheets because they want to create an exact feel as the final examination for the practising student. Many a times users who are unaware or reluctant to accept the benefits of new OMR System also insist on colored OMR printing. However the Addmen OMR Software comfortably accepts the colored OMR Sheets as well.
Colored sheets are usually printed out in two colors. One of the color has to be black and the other one can be any of the basic Pink, Water-Blue, Light-Green, Light-orange or golden-yellow colors. It is important to understand that there is difference of intensity between Magenta and Pink, Blue and skyblue, Green and Light/parrot green, red and light orange.
It has to be kept in mind that the shade of the color used should be light enough to not disturb the black OMR marks when contrasted. Deep colors give black impression when contrasted. So the color intensity should be such that serves the purpose of visually differentiating between sheets, but light enough to avoid any conflict at the time of scanning and reading.
It is strongly suggested that the color proof is sufficiently tested for OMR reading and consulted for suitability before going for bulk color printing.
If the user has decided to print colored OMR Sheets, then following guidelines must be observed:
Colored OMR designs can be printed using a color Laser printer or inkjet printer.
Only 2 colors should be used for the OMR area. Any other designs on the sheet may have as many colors as desired.
One color Black is necessary. Second color can be pink or orange or golden yellow. Green or blue tones should be avoided in printing colored OMR sheet print.
The sheets which expect the candidates to respond by making "tick marks" or "thin line" impression responses should be preferably printed in 2 colors.
The answer sheet designs with OMR bubbles having a text label inside them should be preferably printed in 2 colors.
In case of Offset printing, the corner black index points are printed in both colors, such that they exactly overlap and there is no relative displacement i.e. zero-zero registration.