Samsung ST100 has a
14.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor . On the other hand, Ricoh WG-4 GPS has a
16.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor .
Below you can see the ST100 and WG-4 GPS sensor size comparison.
Samsung ST100 and Ricoh WG-4 GPS have the same sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture. On the other hand, since Samsung ST100 has 14% larger pixel area compared to Ricoh WG-4 GPS, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.