Generally OMR Sheets are printed in specific colors which have a technical reason to be used. Generally pink color is used in combination with black color. Since it is a color complementary in shade and intensity of darker colors like Blue or black, thus it is very easy to selectively identify and handle this pink color on a sheet. Thus we can even eliminate the matter printed in pink so that only the black marks or the area of concern remains on the scanned image of the sheet. This will lead to better identification of the sought black OMR responses more accurately. This process of eliminating specific color during scanning is called "color dropping".
Generally, this facility is available only in high end professional scanners. Colored OMR Sheets can be scanned in color format because Addmen OMR Sheet Scanner software has inbuilt color dropping facility. It has a very convenient facility to adjust sensitivity of color dropping.
If a higher end professional scanner is available, then colored sheets can be scanned in black and white format by color dropping directly from the scanner.
However, if a higher end color scanner is not available, and if the size of black mark is sizeable bubble instead of thin tick marks, then scanning in simple Black & White format is also acceptable.
So the use of a normal price range simple image scanners are absolutely OK for scanning OMR sheets to be used in Addmen OMR Sheet Scanner software.