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Observation

The OMR layout is slightly different on colored thick papers vs on xeroxed thin papers. The shift becomes noticible in case of OMR with large number of questions.

We overlapped a colored OMR sheet with a xerox copy of the same OMR sheet(both printed on A4 papers) and observed that there is a great amount of layout sheet as we reach the bottom of the OMR.

Link to an explainer with a real life example: Google Drive

Reasons for shifts in Template layout:

Listing out a few reasons for the above observation:

Printer margin setting

The margin settings for different printers may be different for the same OMR layout. Thus causing the print to become elongated either horizontally, vertically or both ways.

The Fan-out effect

The fan-out effect is usually observed in a sheet fed offset press. Depending on how the papers are made, their dimensions have a tendency to change when they are exposed to moisture or water.

The standard office papers(80 gsm) can easily capture moisture and change shape e.g. in case they get stored for multiple days in a place where the weather is highly humid.

Below are some examples of the GSM ranges:

• 74gsm to 90gsm – This is the basic standard office paper, used in your laser printers.

• 100gsm to 120gsm – This is stationary paper used for standard letterheads, complimentary slips.

• 130 to 170gsm – Mostly used for leaflets, posters, single-sided flyers, and brochures.

Solution

It is recommended to scan each types of prints into different folders and use a separate template.json layout for each of the folders. The same is presented in this sample folder.

References

• Paper dimensional stability in sheet-fed offset printing

• An analysis of a few "Interesting" bubble sheets