Why does Digikam not display some images it knows are there?

Digikam shows me two numbers for any given search, one in parentheses and then a larger one after it in square brackets. The former is the number of images it displays, but the latter is the real number of such images in the folder on my hard drive. Why is it not displaying those remaining images if it knows they’re there and they’re of a compatible type (.jpg/.png/.gif)?