NOW that colour printing is becoming the norm among many home and office computer users, it is important to look at the various colour technologies that are available along with their merits and demerits. The main methods of colour printing are inkjet, laser, thermal wax and dye sublimation. Each has particular advantages and falls into distinctly different market segments based on price. At the low-cost end of the range, the only viable choice today is inkjet technology. Although there are emerging lower-cost dye sublimation and thermal wax printers, they are still costlier than the inkjets and, in the case of the dye sublimation choices, the performance can be quite poor. Colour inkjet printers work by using either three or four colours of ink. In the case of some low-end printers, only cyan, magenta and yellow inks are used to produce an acceptable range of colours. However, the lack of black ink means that dark colours can appear muddy and somewhat brown. Newer, somewhat costlier models use all four colours to produce a complete range including true black. There are mid-range colour inkjet printers that produce considerably higher quality results than the low-end personal use models that have made such an impact on the market during the past year. A perfect example of this is the Hewlett Packard DeskJet 1200C which, while priced at more than US$1,000, produces colour quality significantly better than the low-end colour inkjets from HP, Canon and Epson, among others. While the initial up-front cost of ink jet printers is considerably lower than other alternatives, there are several things to watch out for. Their consumables can be quite costly - potentially as much as four times that of laser printers. Also, because they use ink that soaks into the paper, images with a high ink density are prone to curling and warping because of the volume of ink that is in the paper. Also, while inkjet printers can print on plain paper, often the best results are to be found on somewhat costly coated papers specially designed to absorb inkjet ink without the spreading that causes a bluriness and results in lack of intensity on plain paper. Laser technology is a tried and tested black and white technology and can produce quite good colour output. Colour lasers use four colours of toner that are applied to the page using the same method as basic black and white laser printers. Essentially, a laser beam is aimed at a photo-sensitive drum that then picks up particles of each colour of toner in turn and applies it to the paper. Unlike inks, toner can be applied in much higher density, and is not prone to bleeding. The real advantage with laser printers is that they can print on both plain paper and laser transparencies without any difficulty. Generally considered to be in the same class as colour laser printers are thermal wax printers. Unlike laser printers, thermal wax printers - as the name would suggest - melt wax on to the paper and, much like laser and inkjet printers, produce dithered, dot-based output to simulate multiple colours and continuous tone images. Most thermal wax printers, though, require the use of special coated papers which can mean increased costs of consumables. At the true high-end is dye sublimation printing. Dye sublimation technology, rather than using combinations of dots to produce a simulation of continuous tone images - in the way that is done with offset press printing - combines varying intensity of dyes to produce photo-quality, continuous tone images. While the images are spectacular and the colours rich, the big drawback lies in the high cost of hardware and consumables. Both the dyes and the special paper cost considerably more than with most other colour alternatives. For users who want access to the quality output offered by dye sublimation technology but cannot justify the cost of proofing their colour work with dye sublimation consumables, some vendors have begun to offer dual-method printers that can be switched between thermal wax and dye sublimation printing allowing proofing to be done with wax and final output with dye. In fact, one vendor, Fargo, has shown that it is even possible to bring the cost of these printers down to a starting point as low as US$1,000, although it has sacrificed resolution, image quality and print speed in order to do this.