This is our standard studio scene comparison shot taken from exactly the same tripod position. Lighting: daylight simulation, >98% CRI. Crops are 100%. Ambient temperature was approximately 22°C (~72°F).
Sony DSLR A330: Aperture Priority, ISO 100, JPEG Large/Fine, Manual WB
Default Parameters, Self-Timer
Sony DSLR A330
2.6 MB JPEG (2640 x 1760)
3.1 MB JPEG (3872 x 2592)
Although the Olympus E-P1 managed to capture almost as much detail as the DP2, the same doesn't appear to be true of the A330, with no real detail in the horizontal bars on the medals in the third crop. As such, you wouldn't expect downsizing to produce as detailed an image as the Sigma can produce. The Sony is producing colors that are more punchy (despite the Sigma being used in the Landscape mode that boosts its saturation), and more consist across the frame.