Like previous PowerShot models the G6 provides a range of preset image parameter settings (Canon call these 'Effects'). In addition to the six presets (including Normal) there is a Custom setting which allows you to adjust contrast, sharpness and saturation by one level plus or minus. Once more I'll voice my disappointment that Canon didn't see fit to provide owners with a wider latitude or finer level of adjustment, perhaps -/+ 3 for each parameter.
Image parameter adjustments
- Contrast: -, 0, +
- Saturation: -, 0, +
- Sharpness: -, 0, +
Adjusting the tone alters the shape of the curve used to map the linear image data captured by the sensor into the correct gamma. A lower contrast setting maintains more of the original data's dynamic range but leads to a flatter looking image. A higher contrast setting stretches the grayscale (dark to light) of the image and could lead to clipping of both shadow detail and highlights.
Saturation adjustment allows you to control the strength of color in the final image. As you can see the minus and plus settings provide a fairly strong swing in color response, once more a finer level of adjustment would have been more beneficial.
To avoid halo sharpening artifacts completely you can set the G6's sharpening to the '-' level although this will of course leave images looking soft straight out of the camera (if you're used to post-processing this won't be an issue). A finer level of adjustment between the '-' and '0' levels would have been useful here as it would have been possible to get a good compromise between out-of-the-camera sharpness and halo artifacts.