Camera obscura in the context of "Exposure (photography)"

A photograph (also known as a photo, or more generically referred to as an image or picture) is an image created by light falling on a photosensitive surface, usually photographic film or an electronic image sensor. The process and practice of creating such images is called photography.

Most photographs are now created using a smartphone or camera, which uses a lens to focus the scene's visible wavelengths of light into a reproduction of what the human eye would perceive.

Sfumato (English: /sfuːˈmɑːtoʊ/ sfoo-MAH-toh, Italian: [sfuˈmaːto]; lit. 'smoked off', i.e. 'blurred') is a painting technique for softening the transition between colours, mimicking an area beyond what the human eye is focusing on, or the out-of-focus plane. It is one of the canonical painting modes of the Renaissance. Leonardo da Vinci was the most prominent practitioner of sfumato, based on his research in optics and human vision, and his experimentation with the camera obscura. He introduced it and implemented it in many of his works, including the Virgin of the Rocks and in his famous painting of the Mona Lisa. He described sfumato as "without lines or borders, in the manner of smoke".

According to the theory of the art historian Marcia B. Hall, which has gained considerable acceptance, sfumato is one of four modes of painting colours available to Italian High Renaissance painters, along with cangiante, chiaroscuro, and unione.

Joseph Nicéphore Niépce (French: [nisefɔʁ njɛps]; 7 March 1765 – 5 July 1833) was a French inventor and one of the pioneers of photography. Niépce developed heliography, a technique he used to create the world's oldest surviving products of a photographic process. In the mid-1820s, he used a primitive camera to produce the oldest surviving photograph of a real-world scene. Among Niépce's other inventions was the Pyréolophore, one of the world's first internal combustion engines, which he conceived, created, and developed with his older brother Claude Niépce.

The paper negative process consists of using a negative printed on paper (either photographically or digitally) to create the final print of a photograph, as opposed to using a modern negative on a film base of cellulose acetate. The plastic acetate negative (which is what modern films produce) enables the printing of a very sharp image intended to be as close a representation of the actual subject as is possible. By using a negative based on paper instead, there is the possibility of creating a more ethereal image, simply by using a type of paper with a very visible grain, or by drawing on the paper or distressing it in some way.

One of the original forms of photography was based on the paper negative process. William Henry Fox Talbot's paper negative process, which was used to create his work "The Pencil of Nature", used a negative created on paper treated with silver salts, which was exposed in a camera obscura to create the negative and then contact printed on a similar paper to produce a positive image.

Heliography is an early photographic process, based on the hardening of bitumen in sunlight. It was invented by Nicéphore Niépce around 1822. Niépce used the process to make the earliest known surviving photograph from nature, View from the Window at Le Gras (1826 or 1827), and the first realisation of photoresist as means to reproduce artworks through inventions of photolithography and photogravure.

The history of photography began with the discovery of two critical principles: The first is camera obscura image projection; the second is the discovery that some substances are visibly altered by exposure to light. There are no artifacts or descriptions that indicate any attempt to capture images with light sensitive materials prior to the 18th century.

Around 1717, Johann Heinrich Schulze used a light-sensitive slurry to capture images of cut-out letters on a bottle. However, he did not pursue making these results permanent. Around 1800, Thomas Wedgwood made the first reliably documented, although unsuccessful attempt at capturing camera images in permanent form. His experiments did produce detailed photograms, but Wedgwood and his associate Humphry Davy found no way to fix these images.