Photogravure

Photogravure or héliogravure is a printing method that allows reproduction from photographic images. When the printing plate is a cylinder, the process is called rotogravure.

For stamps and much commercial printing, an image is broken down into a series of fine dots for the printing plate and the printed item. This can be seen under magnification. This allows printed images to show a photo-like degree of shading and detail.

The method came from fine art printing in the 1870s but was not used for stamp printing until the 1920s. This was generally used at the time for printing single colors; accurate full-color printing for stamps was still a few years off. Eventually, very fine and high quality full color photogravure was achieved, most notably by companies like the Swiss printers Helio Courvoisier.

In more recent years, photolithography caught up in quality to pretty much replace photogravure printing.  File:Switz 1929 Pro Juv.jpg|Switzerland 1929 10c+10c Pro Juventute File:Ruanda Urundi flower.jpg|Ruanda-Urundi 1953 15c Protea File:Photograv detail.png|detail from the previous stamp. What appears to be a solid frameline is actually finely dotted. 