grover's algorithm

Grover's algorithm searches an unstructured database (or an unordered list) with N entries. what type of data it works on? will it be possible to search data about some images that is stored in database?

The Grover algorithm in its simplest form searches a list of $N$ bits for an occurrence of a bit with value 1. If a 1 is present, Grover will find one with high probability in $O(\sqrt{N})$ steps.
While this seems quite specific, the algorithm is actually applicable in a variety of settings. For example, say you want to search in a image database for an image that contains a cat. Let us assume that there is some algorithm $CAT$ that will decide whether a given image contains a cat, outputting a 1 on input $Img$ if a cat is found in $Img$. Suppose $CAT$ requires $S$ steps per image. Then instead of running $CAT$ on all $N$ images (for $NS$ total work), we can run Grover search on the list of $N$ bits, computing the bits only when required by the Grover algorithm. These various calls to the $CAT$ routine are applied in quantum superposition, and the total work required is $O(\sqrt{N}\cdot S)$, a substantial savings.