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There are two different places you can reduce noise in Photoshop CS5: The Noise Reduction controls in Camera Raw rock, however the Reduce Noise filter in Photoshop (under the Filter menu, under Noise) does not. We used to joke that the sliders weren’t connected to anything, and if they were, it was a blur filter. My advice—only use the Noise Reduction in the Detail panel of Camera Raw, and avoid the other altogether.