Although lithography was invented in 1798, it was at first too slow and expensive for poster production. Most posters were woodblocks or metal engravings with little color or design. This all changed with Cheret’s "three stone lithographic process," a breakthrough which allowed artists to achieve every color in the spectrum with as little as three stones - red, yellow and blue - printed in careful registration. Although the process was difficult, the result was a …showed first 75 words of 496 total…

…showed last 75 words of 496 total…show the changes in society, as well as the society itself. Whether or not the poster is designed by a "recognized" artist, when it has aesthetic qualities or particular merit, the poster can change its status from being the means of a common advertisement, it can become a work of art in its own right. So for a good number of them, the border between advertising medium and work of fine art becomes very blurred.