Articles: Monitors

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Surely, the best way to solve the problem is to abandon cold-cathode fluorescent lamps altogether. Some manufacturers have done that, like Samsung did with its SyncMaster XL20. Instead of fluorescent lamps this monitor uses a block of LEDs of three colors as backlight (the LEDs are red, blue and green because the use of white LEDs doesn’t make sense – red, green and blue colors would anyway have to be cut out of the backlight spectrum with filters). Each LED has a neat, flat spectrum that precisely coincides with the pass-band of the appropriate filter and has no extra peaks.

That’s a treat for the eye, isn’t it?

The spectrum of each LED is rather wide, so their radiation can’t be called strictly monochromatic and they can’t match a laser display. Yet they are much better than the spectrum of CCF lamps. Note the neat smooth minimums at those two places where the CCF lamps have unnecessary peaks. Note also that the maximums of all the three peaks have changed. The maximum of red is now much closer to the borderline of the visible spectrum – this should increase the color gamut.

And here is the color gamut itself. The gamut triangle of the SyncMaster 913N isn’t much different from the humble sRGB and green suffers the most in comparison with the gamut of the human eye. But the gamut of the XL20 cannot be mistaken for sRGB – it covers much more of green and blue-green hues and includes a deep red. That’s not a laser display, yet it’s impressive anyway.

Well, we won’t have home monitors with LED-based backlighting for some time yet. The 20” SyncMaster XL20 is expected to arrive in this spring at a price of $2000 while the 21” NEC SpectraView Reference 21 LED costs three times that money! Only polygraphists (these models are mainly targeted at) are accustomed to such prices, but not home users.

However, there is a hope for us, too. There have arrived monitors with fluorescent backlight lamps that have new phosphors which don’t have so many unnecessary peaks in the spectrum. Such lamps aren’t as good as LEDs, but are considerably better than the old lamps. The gamut they provide is somewhere in between the gamut of models on the old lamps and with LED-based backlighting.

To compare color gamuts in numbers, it is a common practice to state how much percent the given monitor’s gamut is in some standard color gamut. The sRGB color space is too small, so they often use NTSC. Thus, ordinary sRGB monitors have a gamut of 72% NTSC. The monitors with improved backlight lamps have a gamut of 97% NTSC and monitors with LED-based backlighting – 114% NTSC!

What does the enhanced color gamut give us? The manufacturers of monitors with LED-based backlighting usually post photographs of their new models next to older ones in press releases and simply increase the color saturation of the new models. That’s not correct since only the saturation of those colors that don’t fit within the old monitors’ gamut is improved. But viewing such press releases on your old monitor, you won’t ever notice the difference because your monitor cannot reproduce such colors anyway. It’s like trying to watch a report from a color TV exhibition on a black-and-white TV-set. On the other hand, the manufacturers have to show the advantages of the new models one way or another in their press releases.

There is a difference in practice, however. I wouldn’t say a great difference, yet the enhanced-gamut models are certainly better. They produce very pure and deep red and green colors. If you work for a while at a monitor with LED backlighting and then return to a monitor with CCF lamps, you involuntarily try to add saturation until you realize that it won’t help. Red and green will anyway remain somewhat dull and muddy in comparison with the LED monitor.

Unfortunately, the models with the improved backlight lamps have been spreading out not in the way they should have done. For example, Samsung first employed such lamps in its TN-based SyncMaster 931C. Low-end monitors on TN matrixes wouldn’t get worse for having an enhanced color gamut, but I guess few people buy such models for work with color due to their obviously poor viewing angles. Well, all the major manufacturers of LCD panels – LG.Philips LCD, AU Optronics and Samsung – have already developed S-IPS, MVA and S-PVA models panels with diagonals of 26-27” and with the new backlight lamps.

Lamps with the new phosphors will eventually oust the older ones and we’ll move beyond the humble sRGB gamut for the first time in the history of color PC monitors.

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