lucy24 - 9:21 pm on May 2, 2013 (gmt 0)
Huh. From where I'm sitting, it's the one labeled "bottom" that looks darker :)
Actual color values seem to vary within each box. Looks as if both are intended to be around 229/142/26 but in the bigger box the red value can drop down to around 211 with similar but smaller drops in the other two colors. The smaller box-- the one with text-- has much less variation.
Do you get the same effect if you save as a png? If it's all the same color, you'll probably get more accurate values and a smaller filesize. And if the text is part of your image, then you'd want to go with png in any case.