An early photographic process invented by William Henry Fox Talbot and patented in 1841. Paper coated with silver iodide was exposed in the camera, and the hidden image was then developed with chemicals. The result was a paper negative, from which many positive prints could be made. This was its big advantage over the daguerreotype, which could not be copied.
Calotypes are softer than daguerreotypes because the paper fibers scatter the light. In the 1850s the collodion process, with glass negatives, replaced it. The negative-positive principle remained the basis of film photography.
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