Canon A650 IS PowerShot - very happy with it, but is it possible to alter the MP's down from 12.1 to say 6MP for smaller files?

I'm otherwise very happy with it, but would like to alter the MP's down from 12.1 to say 6MP for smaller files- is that possible? What I want is 1/2 or even 1/4 size files (average pic is 2.5 - 3.0 MB right now, and I'd prefer say 1 or 1.5 MB) Can't see any obvious references on how to do this in the manual or even palying with the camera menu functions. Help, please!?

Basically there's two ways to do this, one in the camera before shooting the picture, one after shooting the picture. First, there should be an option in the camera that lets you choose the picture size (under the menu), choosing a smaller size will lower your megapixel count, and is probably the easiest way if you want the megapixels lowered on all of the pictures. The second is, after you transfer all of the pictures to your computer, find a batch image resizer (just search on google, there are tons), then download that and resize all of your images as small as you want them after that.

Setting your camera to a lower setting doesn't help. Essentially, the image is reduced to the set quality after it has been processed by the CCD. As such, the light still goes through those pixels, only that after some basic processing steps pixels "thrown out" to make the image to the desired setting and size. This process is called "Choking" and that will cause Artifacting and noise. Additionlly, you'll also loose details of the recorded image.

Some cameras have written into their firmware a process called "binning," which merges the signals of multiple pixels to make larger pixels. Usually at a 4-1 ration. This will essentially turn a 12-megapixel camera into a 3-megapixel camera. And that gives you the opposite problem of too many pixels on the chip ... you now have too few and as such, will run into artifacting instead of noise.

In camera -- press func. button, scroll to size, choose size (L, M1, M2, M3, S, Postcard), press func. button to set it.
In computer -- download Picasa3 FREE from Google and use to organize photos and resize as well as adjust exposure, etc.