So often these days a 10-megapixel compact means images full to bursting with noise, Fuji has 
gone a long way to controlling that noise in its cameras and on the evidence of this camera, Pentax has been working hard to subdue it too.
The A20 is a neatly designed, well-made compact featuring innovations that help to set it apart from the 10-megapixel pack. The A20 has an advantage with its sensor, a larger-than-most-10-megapixel, 1/1.8-inch type CCD controlled by a new image-processing engine or ASIC (Application Specific Integrated Circuit) so noise is reduced and sensitivity improved.
Much is made of anti-shake these days and usually for a 3x-zoom, the A20 also employs it but in three forms. There’s Pentax’s proprietary CCD-shift system to help with camera shake, there’s special high-sensitivity anti-blur system to help reduce blur from subject movement by boosting the sensitivity up to ISO 1600 so faster shutter speeds remain available. The downside of the anti-blur mode is it fixes the resolution to 5-megapixels and noise does become obvious.
Finally, the anti-shake system can be rolled out into the movie mode as well, but it uses software to reduce blur and this has the unfortunate side effect of reducing the field of view available to the camera’s sensor and introduces extra noise and reduces detail a tad as well. Pentax Optio A20 digital camera Review - Pocket-lint.co.uk