What was the first type of photograph invented by Niépce?

The first type of photograph invented by Niépce was called a heliograph. He developed this process in the early 1820s, and it was the first successful attempt to create a permanent image using a camera. Niépce used a pewter plate coated with a light-sensitive substance called bitumen of Judea, which hardens upon exposure to light. The plate would then be exposed for several hours to capture the image. This early form of photography laid the groundwork for future developments in the field.

The other options represent different advancements in photography, but they occurred later in its development. The daguerreotype, developed by Louis Daguerre in 1839, was the first commercially viable form of photography. The calotype, invented by Henry Fox Talbot, introduced a negative-positive process that further advanced photographic techniques. The direct positive process, used in various forms, also emerged after the invention of the heliograph. Each of these alternatives reflects various technological progressions in photography that built on the foundation laid by Niépce's initial work with heliographs.