Inkjet printing has revolutionised colour printing, making it affordable for all. The inkjet market is huge, and a goldmine to any manufacturer that can stake a claim. Unfortunately this has led to a goldrush of inflated claims and bewildering jargon. We took the bull by the horns to make sense of all the hype.

* Resolving the resolution

The numbers game is the competitive sport played by inkjet printer manufacturers to try and outdo the competition. It usually centres on something like dots per inch (dpi) for resolution - the theory being the more dpi a printer can print, the smoother the image will be.

Logic seems to support this theory, however manufacturers’ definitions of what constitutes a dot vary. Traditionally a dot on your screen should correspond with a dot on your page. But with printers such as the Epson Stylus Photo series, offering 2,880dpi, your original image would have to be huge to take advantage of all those dots. What actually happens is that a normal resolution image (around 300dpi) is used, but each of the dots, or pixels, on your screen is made up of many dots on the printed page. This means the extra dots are not adding extra detail to the image. The extra dots are just smoothing the printed image.

HP (Hewlett-Packard) uses a different method to get smooth colour. Instead of making each screen dot out of lots of smaller ones, it uses layering. This means each dot is made up from a number of dots on top of each other. This helps HP printers get a wide range of colours with only 600dpi. Compare 600dpi with 2,880dpi with the Epson range and the difference is slight, due to the different methods used. HP understands that a 600dpi printer sounds like it should be worse than a 2,880dpi printer, so it has added the capability of printing 2,400dpi. This mode isn’t recommended by HP and it doesn’t offer an improvement over the 600dpi mode; it is simply there to play the numbers game.

The lesson is simple, while big numbers on the box look more appealing, there is no guarantee it will improve the image quality.

* Speed trials

Another thing you will see on printer specifications is the speed of the printer. Again, this is a number that means very little. Sure, some printers are faster than others, but there is no standard speed test, and print speeds of inkjet printers vary with lots of different factors. For instance, if you print a full-page colour image from any inkjet printer it will take longer than a page of text. That is simple enough. The processing of the image happens mostly in your PC, not the printer. This means that if you plug a printer into a top of the range PC, it will process the image quicker than a four-year-old PC.

So when manufacturers test their printers, you can bet the speed tests are done with the fastest PCs money can buy, printing a haiku in 8 point text. So don’t be disappointed when your 10-page-per-minute printer takes 10 minutes to print an A4 photograph.

I tested 23 inkjet printers and found that, in high-quality mode, print times varied from a minute-and-a-half to over 10 minutes.

* The short life of an ink cartridge

A big expense of owning an inkjet printer is the ink. Some manufacturers admit cartridge prices subsidise both pinter prices and research and development. I’m not saying this isn’t something we should be paying for, but it is a bit sneaky.

Of the 23 printers tested, we took a smaller sample to test ink life. This involved printing a page with a few photographs and some text at the best quality setting. This is a worst-case scenario for an ink-life test.

The results were quite an eye-opener. Some models managed less than 50 pages before running out of steam, and some got over 200 pages out. The worst performers were the Lexmark Z12, managing 44 pages, and the Epson Stylus Photo 890. In a way you could almost forgive the Lexmark - at a mere pound;56 it was the cheapest tested.

The Epson, however, managed only 43 pages, and at pound;187 you may be forgiven for expecting less of an ink mark-up. Other Epson models such as the Stylus Color 980 did much better with 155 pages, though this printer cost a shade over pound;300.

The HP 900 series use the same print engine, so should get similar results. The DeskJet 990 managed 91 pages, but when equipped with a double-life cartridge managed more than double at 256 pages.

Filling a printer with colour ink will cost on average pound;30, unless you go for the HP double-life cartridge at around pound;60. This means the price for a full colour page can vary in cost from 20p to pound;1.50 per page.

* Winners and losers

The results of our tests turned up some excellent bargains. If you want to use a printer in the classroom, any of the HP 900 series models are high quality and economic. The double-life ink cartridges make for affordable colour, the DeskJet 930C at pound;129 takes advantage of that, and although a little slow, it is our top choice for economic printing.

If money is not so tight, the HP PhotoSmart 1218 is full of bells and whistles that make it ideal for schools. Designed for use with digital cameras as well as computers, it has a memory-card reader built in. This means you can bypass the computer and print photographs directly from the camera media. It also has automatic head-alignment and paper-sensing, making it simple to use. The price tag of pound;299 (inc VAT) may seem high, but the feature set is really useful, and if it cuts the cost of a computer out of the equation, it is even more of a bargain.

Canon has its S600 which scored well on quality, speed and ink-life tests. It uses individual cartridges for each colour so when you run out of magenta, say, you don’t need to throw the other inks out.

For top quality prints, Epson leads the way with the Stylus Photo range. Both the A3 and A4 models, the 890 and 1290 respectively can do excellent quality and edge-to-edge printing. The only drawback is their terrible thirst for ink - they are the Rolls Royce of inkjets, lovely if you can afford the fuel.

The Epson Stylus Color series is less thirsty for ink, and the quality is pretty good too. The top model in the range, the 980 is extremely fast, but twice the price of the equally capable but slower 880.

Whichever printer you choose, don’t be drawn in by the resolutions or speeds. It is worth taking a careful look at how much it costs to fill it with ink, because it is likely that over the life of the printer you will be paying more for the ink than the printer.

David Fanning is the deputy editor of Macworld magazine which published the results of his inkjet testing in its April issue. davidf@macworld.co.ukwww.macworld.co.uk