Zoomed-out to wide angle, the PowerShot G7 delivers good results in its corners with only a small hint of coloured fringing and softness when the aperture is wide open. Interestingly the results are very comparable to the PowerShot A640, despite them employing different lenses. The Panasonic DMC-FZ50 has a slight edge over the two PowerShots, although all three deliver a noticeably superior result to the Canon EOS 400D / XTi's kit lens in this test when zoomed-out.
Zoomed-in to its telephoto end, the PowerShot G7 again delivers good results, this time with no fringing to worry about, although the crops are slightly softer than the A640's at smaller apertures; to be fair, the lens range is longer though. The Panasonic DMC-FZ50 shows a little more coloured fringing than its rivals here, although again it's offering a much greater focal range. All in all though, a decent result for the PowerShot G7 lens, which delivers a respectable degree of sharpness across its entire frame.
Note: the Canon EOS 400D / Rebel XTi captures a wide 3:2 aspect ratio frame, hence the different numbers in the crops. Each crop still represents the extreme bottom left corner of the frame though.