What is Marks Sense Recognition?

Marks Sense Recognition: a quick reality check 

Introducation to Marks Sense Recognition 

OMR refers to the technique of converting a handwritten mark intoan ASCII value. The Mark is created by filling a circle or a box on a pre-printed form. 

The presence or absence of a Mark in a specific location is then converted into a value such as a selection in a multi- choice question, the selection of one item in a list of several, or even to code a specific numeric or alphanumeric value, such as a date using six columns of 10 boxes. 

Thus, if a Mark by itself can only generate a binary choice (presenceor absence), the combination of several marks arranged on a formcan provide intelligent answers to questions and be used as a fast and accurate replacement to data entry in many applications. 

Optical marks recognition is traditionally performed using Reflective Light Method where a beam of light is reflected on a sheet withmarks. Special forms are created using Timing Marks and colordrop-out and are usually referred as OMR forms from the name of the vendors that sell these systems. DataCap can assist you in locating a vendor for such a product. Please Contact us for details 

On the other hand, techniques used to process marks from a scanned document raised different issues such as background color, density of marks, coding scheme, timing marks etc.. 

Software based solutions: the issue of registration 

Marks recognition can be achieved with specially designed formsor free forms. The problem of free forms (without timing or registrationmarks) is accuracy and control. If the marks are too close andare filled slightly inaccurately, the error rate can be extremelyhigh. In addition, template setting is longer and more complex.It is possible to read the form without timing marks, howeverprocessing time is usually longer and forms set-up more complex 

OMR Forms using Timing Marks 

Timing marks are short black lines printed at the edge of theform, one mark per line. The timing marks provide for an accurateposition of the data. This technique is used by all hardware base solutions. 

When timing marks based techniques are used, the position of themark is extremely accurate and density check can be performedon the area of the grid quickly and accurately. Density checkis done by using a fixed or relative threshold. 

Since marks can be printed very close to each other, it is possible to create a grid of 10x10 or 20x26 that can be used to code a number or a name. Usually a character is printed inside the bubble which requires that the form be printed in a drop-out color for the scanner (usually light green and blue for green lamp scanners and light red for red lamp scanner). White light scanners do not work very well in these application because the background appears and makes the threshold decision between a filled mark and anempty mark difficult to decide. 

This technique, however accurate and fast is not appropriate for other types of marks such as check boxes. Here simple density checks often generate invalid results because the difference betweenthe density of a filled mark and that of an empty mark is marginal.