THE camp of Democratic presidential hopeful Hillary Clinton camp has been accused of deliberately darkening the skin of opponent Barack Obama in a new ad. The controversial footage has been compared to images shot of Senator Obama during a debate in Cleveland last week - with critics claiming a screen grab used in the Clinton ad had been altered to highlight his race. A posting on the liberal website DailyKos shows the two images side by side. Despite the strong similarities between the ad on the DailyKos site and the original ad on Senator Clinton's website, Clinton spokesman Jay Carson distanced the team from the controversy. He said on Fox News that he had spoken with the campaigns chief ad-maker, Mandy Grunwald, who emphatically denied the ad on DailyKos was theirs. "We don't know what is up there, but it is not our ad," Mr Carson said. However, he said Senator Obama's image was darkened as part of a saturation-desaturation process typical in commercial production and sent in an example of a Clinton ad featuring the candidate and the original footage of Senator Clinton delivering the campaign speech used in the ad. He said both candidates had done it in their ads and there was no ulterior motive. The Obama campaign had no comment.