Test graphic element

Graphic element used in a test, a CAPTCHA or a graphic element used as a test in a quiz or game. Example: a series of graphic elements presents a detail from a famous painting. You need to recognise the title and painter of each painting. In this situation, it is not possible to give a relevant alternative (for example the name of the painting and/or the painter) without rendering the test unusable. In this case, the alternative must simply give the possibility of identifying the graphic element, for example "test image 1".