Color Picker in Photoshop is wrong

I'm having problems with my color picker in photoshop CS5

Image 1: I select the black [ish] bar. Color picker returns gray.

Image 2: I select the white [ish] background below the black bar, color picker returns lighter gray.

Now I thought the color picker was using grayscale, so to test, I did the same with blue.

Image 3: I select the blue, color picker returns wrong blue.

Image 4: I select the blue color one pixel higher than in image 3, color picker returns an even lighter blue. It's still the wrong blue, and the blue in image 3 and 4 is a solid color.

Note: there are no layer styles present!