James Clerk Maxwell demonstrated the first color photograph in a lecture to the Royal Society of Great Britain in 1861. He used the demonstration to illustrate Thomas Young's idea that human vision uses three kinds of light sensors. This demonstration led to a great variety of color photographic systems using both additive and subtractive color. Today, we have image-capture devices that are photographic, video, still, and scanning. We have hardcopy printers that are electrophotographic, ink jet, thermal and holographic, as well as displays that use cathode ray tubes, liquid-crystal and other light emission color devices. The major effort today is to get control of all these technologies so that the user can, without effort, move a color digital image from one technology to another without changing the appearance of the image. The strategy of choice is to use colorimetry to calibrate each device. If all prints and displays sent the same colorimetric values from every pixel, then the images, regardless of the display, would appear identical. The problem with matching prints and displays is that they have very different color gamuts. A more satisfactory solution is needed. In my view, the future emphasis of color research will be in models of human vision. The purpose of these models will shift from calculating color matches to calculating color sensations. All the technologies listed above work one pixel at a time. The response at every pixel is dependent on the input at that pixel, regardless of whether the imaging system is chemical, photonic, or electrical. Humans are different. The color they see at a pixel is controlled by that pixel and all the other pixels in the field of view. Human color vision uses a spatial calculation involving the whole image. Except for human vision, all other color systems have the same output from a single input. In other words, if an input pixel has a value of 128, and the image processing changes that value to 155, then all pixels with 128 in will have 155 out. Human vision is unique among color imaging systems because a single input value (128) will generate a range of output values (0, or 55, or 128, or 255), depending on the values of other pixels in the image. Despite the remarkable progress in our ability to control the placement of dyes and pigments on paper, we must now return to the study of Maxwell's interest—color theory—for the next advancements in color systems. In the future, we will see more models that compute the color appearance from spatial information and write color sensations on media, rather than attempting to write the quanta catch of visual receptors.