I've been trying to work out what difference having I-Contrast set to AUTO or OFF has on photos. I managed to get almost identical clips of a picture, with and without I-Contrast enabled. It seems that with I-Contrast off, anything in shadow becomes very dark and black. With I-Contrast on AUTO, there are more gradations of shadow - as in this photo.
It seems though, that while the leaves become more visible with I-Contrast enabled, the photo becomes more bloomy with light (for example, toward the bottom there are two dashes of light, and in the right photo, one of them is quite glowing with white), a bit blurrier, and I think there are more image artefacts when viewing it at 100% size.
I think I'll stick to having I-Contrast OFF, and if I really want to brighten a photo, or change it's contrast, I'll post-process the image and do it manually.