People have long known that they can project images onto surfaces by using pinholes. An early Arabian physicist, Ibn al-Haytham, is accredited with first developing pinhole cameras as well as the camera obscura – or dark chamber – which meant it was possible to view live images indirectly for the first time. However, it was not until the invention of photo-sensitive plates that such images could first be recorded permanently as stills. Various substances were used to do this in the early nineteenth century, such as vaporised iodine or mercury. The first attempts at photographic film came about in the 1870s. Commercial films were first released by the Kodak company in the 1880s.