1. A method of realism assessment of an image composite, comprising an image processor for performing the following steps: providing the image composite having a foreground and a background; transforming the foreground and the background image composite into a color space, wherein the transformed color space has a first axis representing luminance information, and a second axis and a third axis representing chromatic information; projecting the foreground and the background images to a subspace represented by the second axis and the third axis; and assessing the image composite, in the projected subspace, according to a linearity of color distribution of the foreground image and a linearity of color distribution of the background image, and further according to a relationship between the color distribution of the foreground image and the color distribution of the background image.