Image quality
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Image quality

The G9 and E-M1 II both use a 20MP Four Thirds sensor, and it's fair to say they match up pretty evenly in this category. They do of course use different processors, which will make a difference, and Panasonic has made a lot of effort to refine the G9's JPEG engine since the GH5. But we'd expect them to perform quite similarly, and broadly speaking they do.

Analyzing each camera's performance in our studio testing, the E-M1 II produces slightly nicer JPEG sharpening and colors at base ISO, but the G9 pulls just ahead at high ISO. The difference is subtle, but it's one we noticed.

Both cameras offer a high-resolution mode, assembling a large file from multiple images taken while shifting the sensor slightly. The E-M1 II's JPEG output is rendered at 50MP while Panasonic chooses to output 80MP, but both produce an 80MP Raw file. There's some question over whether you really get 4x the resolution from this pixel-shift method.

If you're very picky and base ISO JPEG rendering is a priority, we think the E-M1 II holds a slight advantage

These modes are best suited for still life, but nevertheless Panasonic and Olympus have both made efforts to improve results for long exposures of moving subjects. Testing the G9 on some street scenes and the E-M1 II on a waterfall (the one from Twin Peaks, naturally), we came away with some decent results. In both cases you'll see artifacts if you look closely, but they're usable images for certain applications.

Differences in this respect are very, very subtle. If you're very picky and base ISO JPEG rendering is a priority, we think the E-M1 II holds a slight advantage. If it's the very best high ISO JPEG detail and color you're after, the G9 does a bit better in that category.