The A99 has excellent JPEG processing and noise reduction, at least up through ISO 1600. Photos are extremely clean through ISO 400, and you can start to see some slight edge artifacts appearing at ISO 800. There's a noticeable jump in noise suppression between ISO 1600 and ISO 3200, regardless of how bright the scene is.
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The A99 does a very good job of preserving detail in raw files of blown-out highlight areas. Underexposed or deep shadow areas can't seem to be recovered without introducing more color noise than competing cameras, though.