Auction block for Getty Images

Getty Images, the world's biggest supplier of pictures and video to media and advertising companies, has put itself on the auction block and could fetch more than $1.5 billion, people briefed on the situation said Sunday.

The Seattle company hired Goldman Sachs to advise it, these people said.

Getty has attracted interest from several buyers, mostly private equity firms, including Kohlberg Kravis Roberts, Bain Capital and others.

Final bids are due by the end of the month, but people briefed on the auction cautioned it was unclear which firms would submit a bid.

A sale is not assured, because the tightening of the high-yield debt markets has cut off private equity firms from the lifeblood of their business.

Getty, founded in 1995, has grown through acquisitions into a go-to source for visual media, claiming an average service of 3.2 billion images and 4 million unique visitors at its Web site each month.

The company's main selling point is the licensing of high-quality images from professional photographers around the world.

Among its main clients are advertising agencies and media companies. It also offers video footage for use in movies, television and the Internet.

A spokeswoman for the company contacted last week said the company does not comment on "rumors and speculation."

Its main rivals, Jupitermedia, and Corbis, a private company owned by the Microsoft founder Bill Gates, have also made a number of acquisitions, though they remain far smaller than Getty.

The Internet — a medium that Getty pioneered by being the first to license images online — has made it easier for clients to find pictures for less money.

Getty's shares have declined more than 47 percent in the last year. In November, it reported a third-quarter profit of $25.7 million, down 31 percent from a year ago.

Last April, Getty also restated its earnings and took a $28 million to $32 million charge after an internal investigation into the backdating of stock options grants to executives.