About dye sublimation:
Both conventional chemical photo prints and modern digital color prints use the subtractive primary colors which are cyan, magenta and yellow. Cyan is red + blue, and it is the opposite or complement of red. Magenta is red + blue, the complement or opposite of green. Yellow is red + green, the complement of blue.
We must use these subtractive primaries because we view color prints on paper via an adjacent light source. Light from this lamp (or sun) plays on the paper, transverses the dye or pigment, is reflected from a white subbing layer and returns to our eye via a second passage through the dye or pigment.
The fact that the viewing light makes two transits is why we choose cyan, magenta and yellow. Cyan acts to block and therefore control how much red light our eyes receive. Likewise, yellow is the blue controller and magenta the green controller. Other colors have been tried, but nothing yet works as well as the subtractive primaries. By the way, color film, both negative and positive, also use the subtractive primary method (CYM).
The CYM system is flawed because we have never obtained the exact colors needed. Yellow is very very good, magenta is OK, but cyan leaves much to be desired. If they were very good, when they overlap, a deep black is seen. This is not the case; we only get a dark gray. To bolster the system, when paper prints are made, we add a black dye or pigment. This black keys off the tones and is called the key color. Now we have a system we call CMYK.
The problem is, the dye and pigments we must use are “fugitive” meaning they are prone to fading. One solution is to use pigments as they are hardier than dye. These can be imbedded in wax and applied to a flexible ribbon. The dye sublimation system uses CMYK pigments. A hot needle vaporizes the wax pigment. The solid wax converts to a gas skipping the liquid stage. This is sublimation. The pigment vapor diffuses into a special permeable coat on the paper. The gas cools and the pigment returns to a solid, skipping the liquid stage.
This method allows improved pigments to be used that are hardy, and the shades are very good though not perfect.