i have to positioning an image between the bottom of two div, one inside another like:

The code for this example is:
<div style="background:blue;width:500px;height:150px;overflow:hidden;">
<div style="background:red;width:500px;height:100px;margin-top:20px;">
//DOES IMAGE GOES HERE?
</div>
</div>
I know that with position absolute i could positioning the image there.. but i don’t like that kind of positioning.. is there another way? Thanks!!!
Full css sample