PARIS, Aug 31 (AFP) - When Deutsche Grammophon unleashed the first vinyl records on to an unsuspecting public 50 years ago, no one could have had the slightest idea of the subsequent cultural impact it was to have. Quite apart from bringing music of all kinds to a mass audience, the very format of the record's cardboard covers would spawn an entire popular sub-culture, namely "album art". With the advent in the 1960s of early experimental forays in the sphere of pop music, the album cover came into its own as a vehicle for painters, photographers, comic strip artists and graphic designers to create small works of art in their own right. The early 12-inch (30cm) records featured little more than wooden-looking, smiling photographs of the performers or, in a vain attempt at a sales pitch, pictures of scantily-clad young women. But by the 1960s, not only were the Beatles and the Rolling Stones arguably the most innovative musical acts around, they were also responsible between them for some of the most memorable examples of album art. The Stones appeared in the first 3-D cover with "Their Satanic Majesties Request" and would later cause mild outrage with the cover of "Sticky Fingers", which featured a picture of a pair of denim jeans, complete with a real zip fastener which could actually be undone to reveal an expanse of flesh beneath. The reference work for all album art, though, remains the Beatles' "Sergeant Pepper's Lonely Hearts Club Band", a brilliant photo-montage by the British artist Peter Blake of major figures of the 20th century, from Albert Einstein to King Kong and Marilyn Monroe. By the time that record was released, album cover art was already developing as a recognised form, inspired to a large extent by Andy Warhol's famous "banana" cover for the Velvet Underground's album, "Peel Slowly and See". As the so-called psychadelic era reached its height, covers like Cream's "Disraeli Gears" featured balloon-like lettering and strange swirling designs, while underground hero Robert Crumm, the man behind the Self-Loathing comics and the pornographic cartoon strip, Fritz the Cat, designed a whacky cover for the album "Cheap Thrills" by Big Brother and the Holding Company, featuring a young Janis Joplin. The German band Faust produced the first transparent disc in a transparent cover, taking the notion of the Beatles' "White Album" with its minimalist plain cover, to an even more elaborate extent, while gimmicks abounded: from the pop-up cardboard cutouts of the band in the centrefold of Jethro Tull's 1968 "Stand Up" to the highly impractical round cover of the Small Faces' "Ogden's Nut Gone Flake" in the form of a tobacco tin. As with all forms, the attentions of the censor were never far away and explicit nudity always called for a cover-up whether it was the scores of bare-breasted women on The Jimi Hendrix Experience's "Electric Ladyland", the full-frontal shot of John Lennon and Yoko Ono on "Two Virgins" or the Lolita-like youngster on the cover of supergroup Blind Faith's eponymous album - all had to be sold inside brown paper wrappers. By the mid-1970s, punk rock reversed the trend and revived an earlier vogue for photo covers and while picture discs and vividly coloured vinyl had a brief heyday, it did little for the sound quality of the records themselves. And then album art went into a rapid decline, along with the old vinyl albums themselves, for with the increasing popularity of the Musicassette and the Compact Disc, artists found working within the restrictions of small surfaces no match for the broader canvas of a solid 12-inch square cover. Perhaps, though, the current vinyl revival will herald a return to the days when cover design was as much a part of the marketing of a rock album as the record within.