BGK is correct, this picture has too much contrast and saturation, thats why its pixelated slightly, problem is once you put contrast up like that, you can't do much with the image as its of low quality.

And when you save as a .gif its even worse, as the gif cant hold all the colours in it like the .jpg can, even the best quality of .gif. Gifs are a thing of the past and should only be used for buttons in my opinion.