The most endearing image mode in the GRD IV to me is the Bleach Bypass emulation, which renders the final images with a black-and-white superimposed on color quality. This playful mode is available in other cameras like the Pentax K-01 too. The result is said to be film-like, but I think it depends on the kind of film being in reference. Surely with an increased contrast and more grainy feel the final image is bestowed.
The emulation works best in a scene where there is a good or, even better, high contrast of the bright and darken areas where your main focus is on the bright side. A bleached image leans on accentuating the bright areas and suppressing the darken ones, thereby making your focus prominent. However, the exposure latitude is therefore lowered and the data in the darker parts may become minimal. But minding the bright spots suffice to end up with a Bleach Bypass image all right.