Are Horses color blind?

According to this article about color blindness in horses by the Journal of vision (2001), the researchers note that horses are not color blind and that a horse has limited dichromatic color vision:

This article show the simulated color blindness of a horse compared to human vision.  In sum, horses are not color blind but have a limited range of color vision, especially for the "nature" colors of brown and yellow tones.

Human color vision:

Horse color vision: