The field of radiology dates back to 1896 with the first direct x-ray exposure of film by Roentgen. From the next 80 years the exposure of black-and-white film by x-rays, and later, from calculated images from CAT scans, ultrasound scans, and MRI scans would dominate the hardcopy world of medical imaging. The uses of color were largely experimental and limited until the development of real-time color Doppler imaging in the early 1980s. Since that time, the uses of color have grown rapidly as 3D visualizations and multi-modality or multi-spectral images become widely utilized. The rapid growth of imaging techniques that combine anatomical information with additional functional or molecular information is driving color to the forefront, since additional information needs to be fused in the renderings. Thus, 100 years after Roentgen's experiment, a century of monochrome imaging is giving way to an emerging need for color displays of medical images.