Lumen prints were some of the earliest forms of photography, known as heliograms. Heliography derives its name from Greek origins - helios, meaning 'sun' and graphein, meaning 'writing.' The process was invented in 1822 by Joseph Nicephore Niepce and based off of the inventions of photolithography (using light to pattern things onto a substrate) and photogravure (an etched copper plate coated with a light-sensitive gelatin tissue exposed to a film positive, used to reproduce detailed continuous tones of a photograph). At its simplest base, a lumen print is produced by placing an object on a sheet of photographic paper (the kind used in a darkroom) and then placed in the sun for a certain amount of time. The density of the object placed on the paper has a lot to do with the resulting pattern. If it is dense and does not allow light to pass through, you will get an outline of the object. If it does allow light to pass through, however, you can often see the intricate details of the object, for example the vein structure in a leaf or petal. I tried various natural items, ranging from onion and garlic skins to flowers to fruits. I was especially intrigued by the citric fruits and what their acidity might do. The most incredible result was from a tomato. The resulting image is so realistic that people often think it is a photograph of the tomato slice itself.