  The head-up display (HUD) is an emerging device which can project information
on a transparent screen. The HUD has been used in airplanes and vehicles, and
it is usually placed in front of the operator's view. In the case of the
vehicle, the driver can see not only various information on the HUD but also
the backgrounds (driving environment) through the HUD. However, the projected
information on the HUD may interfere with the colors in the background because
the HUD is transparent. For example, a red message on the HUD will be less
noticeable when there is an overlap between it and the red brake light from the
front vehicle. As the first step to solve this issue, how to evaluate the
mutual interference between the information on the HUD and backgrounds is
important. Therefore, this paper proposes a method to evaluate the mutual
interference based on saliency. It can be evaluated by comparing the HUD part
cut from a saliency map of a measured image with the HUD image.
