Unrecognised Scans (Bug #169)

First scan: it seems that the student played with the binary codes at the top of the page (circled one should not be dark - check on the subject), so that AMC is unable to identify the scaned page. You can erase this on the scan (with any image editor) and process it again with AMC (for my students, I also apply a penalty in this case).

Second scan: the top-right mark has not been recongnized because it does not have the required size (you can see it is a little flattened). On the right side of the window, the green marks are the one that has correct size for a corner mark, and the black ones are too large or too small. You can increase the Edit/Preferences/Scan/Detection Parameters/Marks size max XXX values to let AMC be a little more tolerant, and process again the same scan.

How can we set a penalty after a test has been prepared?

You'll have to make a manual change in the grades... If you often have this kind of problems, you can prepare your exams so that penalty can easily be applied, with something like what I describe (in french) in Codages simples.

Is the Edit/Preferences/Scan/Detection Parameters/Marks size max XXX values documented?

Only a tip for these entries in the preferences window. There should be a description of how AMC recognizes the pages and boxes somewhere, but this is still missing I'm afraid.