Picture Styles is a feature is present in Canon models sold in the past year or two. It impacts subtle post-processing settings:
The current opinion on the Internet appears to be that Picture Style settings do not change the pixels stored in RAWimages but are available as metadata for use by Canon’s post processing software, DPP. Lightroom and other post-processors currently seem to ignore the selected Picture Style (although the information is stored somehow in the EXIF data). Instead, Lightroom, for example, has presets which aim to provide much the same result as the Canon Picture Styles. These are, however, not identical to Canon’s Picture Styles because everyone uses slightly different algorithms.
It would be nice if Canon could explained this a bit better. They do explain how the Picture Styles impact the sharpening, contrast, saturation, and tone parameters. Canon says that all goes well automatically when you use Canon’s own DPP software o process JPG files. But many people use other software – especially for cameras in this price range.
The latest Adobe Camera Raw 5.2 (used by Photoshop and more to read Raw files) also emulates Canon’s Picture Styles. Interestingly, users seem to start believing that Picture Styles from Canon have some magical authority, compared to say other presets you can find from Adobe, DxO or users.
See manual p59.
See brief discussion on RAW format and pictures styles from Chuck Westfall.