Bubble Sheet Scanning - Best Practices (includes VIDEO)


Not what you were looking for? Search here.



Qualities of an Ideal Scan






  1. The camera angle is straight-on, not skewed at an angle.
  2. The black rectangle is fully in frame, with a little space around the edges.
  3. Filled-in bubbles are dark in the viewer, fully filled in, with no reflections off the pencil lead or lamination that can look lighter.
  4. The lighting is even, with no shadows, bright spots, or reflections off of pencil lead, ink, or lamination.
  5. The bubble sheet is flat, not wrinkled or curved.
  6. Unintended answers are completely erased, not crossed out.
  7. The bubble sheet printout is unaltered and good quality (not a copy of a copy, not shrunken).
  8. The quality is clear, sharp, in focus, and the camera lens is clean.
  9. There are no extraneous markings or writing on or within the black rectangle area.

Common Problems and How to Fix Them




Problems with this image:

The camera is not directly over the bubble sheet, but is at an angle, producing a skewed image. Or, if the bubble sheet is being held up to the camera, it is not straight on and perpendicular to the camera. The rectangle appears as a trapezoidal shape in the viewer.


Move the camera so that it is directly over the sheet looking straight at it, or if you are holding the sheet up to the camera, be sure it is straight-on and perpendicular with the camera.

Curves or Shadows  

Problems with this image:

Curves in the page make the lines of the rectangle appear bowed rather than straight.


Also, uneven light caused by bright spots or shadows can make it difficult to scan. Sometimes shadows are caused by objects on the desk - even the camera stand. Built-in lights on cameras can also cause bright spots.


Place the bubble sheets on a flat surface to scan. If you are holding the sheets up, be careful to not curve them - try using a book or clipboard to hold them up straight and flat.

Arrange the scanning environment to eliminate shadows so that the lighting is even. Turn off any camera light that creates bright spots.


Pencil Marks Reflective or Too Light

Problems with this image:

The pencil marks for questions 1-15 are reflecting overhead lights, appearing very light to the camera. It’s hard to tell they are filled in.

Sometimes pencil marks are just too light.


Change the angle to avoid the reflection, try setting the pages on an angled reading stand, or aim the camera at you and hold the sheets up to it.

Turn off direct-overhead lights, or change scanning location to avoid the reflection.

Pencils work well, but the marks need to be nice and dark. Have your students go back over their bubbles or try markers or pens.



Reflecting Ink or Lamination

Problems with this image:

Many schools save money on paper and ink by laminating their bubble sheets and reusing them with dry erase or wet erase markers. These sheets are very susceptible to glares from lights.

Some printer inks are also reflective, and this can cause problems during scanning.


Be sure to find the right scanning angle and lighting situation to avoid reflections from overhead lighting.


Rectangle Cut Off or Obscured

Problems with this image:

The rectangle surrounding the bubbles is not fully in frame.

Also, any obstructions over part of the rectangle (not shown in this example) like fingers, marks or loose papers can obscure rectangle.


The rectangle is critical to scanning, so back your camera away from the sheet so that the rectangle is fully in frame with a little space around the edges.

Also, avoid any obscuring of the black rectangle, QR code, or any bubbles by any object or dark shadow.


Markings On or Within Rectangle

Problems with this image:

There are markings and writing too close to the black rectangle around the bubble area.


There are marks on the QR code.


There are extraneous markings in the bubble area and around question numbers.



The rectangle, QR code, question numbers, and bubbles need to be free from obstructions or markings other than bubbles being filled in.



If you were looking for help with other scanning issues, click here for help.


If this article described your problem, but you are still having trouble, contact Tech Support for more assistance!



additional keywords: not working, errors, wrong, grading, accurate, inaccurate, bubbles, reading,

Powered by Zendesk