Samsung HZ15W has a
12.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor . On the other hand, Pentax WG-1 GPS has a
14.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor .
Below you can see the HZ15W and WG-1 GPS sensor size comparison.
Samsung HZ15W and Pentax WG-1 GPS have almost the same sensor size, so neither of them has any significant advantage over the other in terms of providing control over depth of field when used with the same focal length and aperture.