Private equity firm Hellman & Friedman LLC is pushing ahead with a $4 billion sale of Getty Images Inc, the largest supplier of stock photos, video and other digital content, to private equity, two people familiar with the matter said on Tuesday.

While several private equity firms, such as Bain Capital LLC, have balked at Hellman's $3.5 billion to $4 billion price expectations, other buyout groups, including KKR & Co LP and TPG Capital LP, are still in the process, which is now in the second round, the sources said.

Hellman, which bought a majority stake in Getty in 2008 in a $2.4 billion deal, tapped Goldman Sachs Group Inc and JPMorgan Chase & Co to examine a possible sale or public offering, a person close to the matter told Reuters in May.

The business has seen little growth in earnings before interest, tax, depreciation and amortization (EBITDA) since Hellman bought it but has enjoyed increasing demand for its online imagery products and services. This could lead to Getty fetching a higher EBITDA valuation multiple, the sources said.

Representatives of Getty and Hellman did not respond to a request for comment while KKR, TPG and Bain declined to comment.

In March, Hellman and the company's minority shareholders reaped a $379 million dividend from Getty funded with debt and $115 million of cash. This followed a $504 million dividend at the end of 2010.

In credit notes in March, ratings agency Moody's said Getty's latest dividend recapitalization led to a "moderately high" debt-to-EBITDA leverage of 4.4 times compared to 3.5 times pre-dividend. Getty had revenues of about $945 million in 2011.

Still some buyout firms may be willing to leverage Getty's cyclical business significantly to exploit the shift from print to online media. KKR showed its appetite for such companies last month, investing $150 million in New-York based image database firm Fotolia.

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