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Photochrom, sometimes spelled Fotochrom or Photochrome〔"Photochrom" () is the spelling used by the Library of Congress, for historical reasons, in its classification and description of its collection of such images. Variants of the spelling exist, both in English and in German. "Photochrome" is the English spelling used in some contexts, even by the Library of Congress in a few of its image descriptions. "ドイツ語:Fotochrom" is the German spelling used today by Orell Füssli, the Swiss company that invented the process.〕 (although this term more often refers to later photographic postcards), and also called the Aäc process, is a process for producing colorized images from black-and-white photographic negatives via the direct photographic transfer of a negative onto lithographic printing plates. The process is a photographic variant of chromolithography, a broader term that refers to color lithography in general. ==History== The process was invented in the 1880s by Hans Jakob Schmid (1856–1924), an employee of the Swiss company Orell Gessner Füssli—a printing firm whose history began in the 16th century. Füssli founded the stock company Photochrom Zürich (later Photoglob Zürich AG) as the business vehicle for the commercial exploitation of the process and both Füssli〔 and Photoglob〔(【引用サイトリンク】language=German )〕 continue to exist today. From the mid-1890s the process was licensed by other companies, including the Detroit Photographic Company in the US (making it the basis of their "phostint" process),〔(【引用サイトリンク】 title=MetropoPostcard Guide to Printing Techniques 5 )〕 and the Photochrom Company of London. The photochrom process was most popular in the 1890s, when true color photography was first developed but was still commercially impractical. In 1898 the US Congress passed the Private Mailing Card Act which let private publishers produce postcards. These could be mailed for one cent each, while the letter rate was two cents. Publishers created thousands of photochrom prints, usually of cities or landscapes, and sold them as postcards. In this format, photochrom reproductions became popular.〔Marc Walter & Sabine Arque, “The World in 1900”, Thames & Hudson, 2007 contains about 300 well-reproduced photochromes from around the world.〕 The Detroit Photographic Company reportedly produced as many as seven million photochrom prints in some years, and ten to thirty thousand different views were offered. After World War One, which ended the craze for collecting Photochrom postcards, the chief use of the process was for posters and art reproductions. The last Photochrom printer operated up to 1970. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Photochrom」の詳細全文を読む スポンサード リンク
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