The most common way to implement MIC in printing is by using miniature yellow dots that are invisible to the naked eye. MIC is always printed multiple times on the document. The dots are not visible due to two main factors:
Tracking yellow dots is done by scanning and properly setting the scanning parameters. The key parameters in this process are DPI and compression.
DPI scanning represents the most important scanning parameter. The ideal state is the highest possible DPI because the larger the resolution, the more detail of the yellow dots can be captured in the image.
Image contains scans of yellow dots under different DPI profiles. In order to make the dots visible, the green and blue channels of the RGB color model are switched on the image, making the dots appear as purple. Illustrations that are modified by this change are labeled with the designation "(filter)" in the description.
Compression can reduce the overall quality of the resulting image and thus blur the dots. The best option is to use a lossless format, such as PNG.
Some scanners do not have this option, so it is advisable to set the lowest possible compression value.
To get an overview of the occurrence of MIC, 130 different random prints were collected, which were:
Subsequently, the prints were scanned with high resolution 1200 DPI without compression, in order to confirm the presence of yellow dots. The total number of samples with yellow dot content was 51 out of 130 prints.
| Category | MIC positive | MIC negative | Total |
|---|---|---|---|
| Certifications | 6 | 3 | 9 |
| Invitation cards | 8 | 6 | 14 |
| Vouchers, tickets | 6 | 5 | 11 |
| Information brochures | 11 | 4 | 15 |
| Advertising leaflets | 14 | 45 | 59 |
| Correspondence | 4 | 13 | 17 |
| Others | 2 | 3 | 5 |
| Total | 51 | 79 | 130 |
MIC is present throughout the printed document in repeating sequences. It forms a two-dimensional matrix, in which a dot represents a Boolean value.
The pattern determines the method and rules for the sequential encoding of MIC. It is quite common for multiple manufacturers to use the same type of pattern, or for one manufacturer to use multiple patterns on different printer models.
A single printer can use only one type of pattern.
Each pattern for MIC encoding defines:
Regardless of the pattern used, the MIC print is always repeated across the entire surface of the paper. The parameter that changes depending on the type of pattern is the layout method.
There are three layout methods for MIC printing:
Patterns that use the grid layout print the MIC in columns and rows. Each cell of this grid contains the MIC, so there is no shift or gap between repeating MIC patterns.
The MIC is printed the same way as in the grid layout, but every other cell in the row of the grid does not contain the MIC. Every other row is shifted by one horizontal position, creating the checkerboard layout.
The MIC is printed in adjacent columns, with each subsequent column containing a vertical shift by a predetermined constant. The shift for a particular pattern is always the same for all MIC prints made according to it.
Most patterns contain a small static segment that is always located at the same position of the MIC matrix. The static segment helps determine the pattern type and the boundaries of individual MICs.
This part of the MIC is always the same on all impressions of a given pattern and always violates the dot printing rules defined by the pattern. This is done so that the same dot sequence cannot appear in the part of the MIC that encodes information.
For example, if the pattern does not allow printing dots in adjacent cells, the static segment can violate this rule and print dots in two cells that are immediately next to each other.
Each pattern type uses a unique method of encoding information into a two-dimensional matrix. There is a pattern that simply encodes information binary into columns, but there is also a pattern whose encoding method remains unknown. The encoding method is divided into: