In a method of realism assessment of an image composite, the foreground and the background are transformed into a color space, such as YCbCr, followed by projecting the foreground and the background to a subspace represented by the axes representing chromatic information. The image composite is assessed in the projected subspace, according to linearity of color distributions of the foreground/the background, or according to distance between the color distributions of the foreground/the background and a center of the transformed color space.