As near as I can tell are different parameter sets for the in camera JPEG procession done by the camera. The choice of this setting is important certainly if you intend to use camera generated JPEG images, but it also affects what you see on the LCD preview on the back of the camera, including the histogram and highlight warnings.

• Standard - basic EOS digital color
• Portrait - best skin tones for women and children
• Landscape - impressive blue skies and green trees
• Neutral - greatest latitude for image processing, "restrained"
• Faithful - most like seen by the human eye
• Monochrome

The above is how Canon describes the 6 choices built into the camera. It is also possible to define and load 3 user defined choices into the camera.

None of this affects the RAW capture, although the settings are recorded for "As Shot" defaults to be used by RAW processing software. If Raw images are worked with, any of these can be overridden or changed.

Canon supplies a picture style editor that can be used to generate picture style (.pf2) files. Three of these can be loaded into the camera in addition to the 6 preset styles.

Canon has also incorporated the picture style concept into their DPP (Digital Photo Professional) software, so you can shoot RAW images, then play with different styles using DPP to decide how to pick the camera settings.

One fellow describes the "landscape" style as being like the old Fuji "velvia" film that landscape shooters loved. It yields vivid saturated colors, but pretty much ruins flesh tones. Landscape also lightens shadows. Faithful is just what it says. Neutral gives dull images by comparison, it is claimed that it turns off picture style processing and just gives you a straight image. Standard is recommended for street shots at night. A +1 tone setting for landscape will tame out of control reds. Portrait is not recommended for anything!

Default landscape is 4,0,0,0