Grainy Crystals From Skin My New Samsung LED 7 Series TV Is Grainy. How Can I Improve The Picture Quality?

My new Samsung LED 7 Series TV is grainy. How can I improve the picture quality? - grainy crystals from skin

I have my Sky + box via the SCART cable. If I continue to see from the TV picture is good, but only later. How do I get the crystal clear picture that looks like TV? Can give I would appreciate any help. Thank you.