Traditionally, thermal transfer printing has been a binary process. This means that for a given location on a page, either a dot of colorant is deposited or is not. Various dithering techniques are used in order to create intermediate tone levels. In comparison, variable dot thermal transfer utilizes colorant dots with a continuum of possible sizes. Consequently, dithering techniques used for traditional fixed dot size thermal transfer printing are not needed. This results in greatly improved image quality. The resolution of variable dot thermal transfer has been shown to be considerably better than ink jet or traditional thermal transfer and comparable to dye diffusion. Furthermore, variable dot thermal transfer has speed, cost and permanence advantages with respect to other color printing technologies.
N. M. Moroney, Steve Viggiano, "Color Imaging Using Variable Dot Thermal Wax Transfer" in Proc. IS&T 2nd Color and Imaging Conf., 1994, pp 167 - 169, https://doi.org/10.2352/CIC.1994.2.1.art00046