Images downloaded from the web in a hurry without proper referencing? If you can’t remember who, what or where, try Google Images – Search by Image. Click the camera icon in the search box and upload your mystery image.
Not 100% effective with every image – but it is a useful tool. More details here
TinEye is another free reverse image search tool.
These image search engines have several uses; as described above, to check if your own images have been copied online or to detect visual plagiarism.
Avoid the risk of plagiarism by correctly attributing any images you use in your course work.