Theory Behind LCDSs

Brightness

Many people will insist that today's LCDs are brighter than CRTs and they'll point out the fact that CRTs are measured to have ~100-120 cd/m2 whereas most LCDs are in the range of 120 to 235 cd/m2. Despite these accurately measured numbers, the basic fact is that CRTs look brighter than LCDs. Who's right? Well the catch is in the way ANSI Lumens are measured, and the difference in projection methods.

On a CRT, light is created by a beam of electrons striking the phosphors on the inside face. The more current you have, the brighter the image. If only a small part of the screen needs to be brought to maximum luminance, the beam is able to concentrate all its current there. For measuring brightness, the entire screen is white and so the beam current is spread across the entire screen. In other words, the ANSI lumens (and converted into cd/m2) gives you the worst-case scenario brightness. The peak brightness is typically 5 times greater.

Brightness vs. Distance

LCD screens have a high-output backlight that runs at constant brightness. Each pixel is basically a filter that blocks out certain frequencies of light. Since the backlight always illuminates the screen, having one white pixel on a black background and an entire screen in white does not affect the peak brightness.

What you're really comparing is a CRT which ranges from 100 to 500 cd/m2 against an LCD which typically has a constant 150 cd/m2. Since most pictures rarely contain pure white, CRTs frequently end up subjectively looking brighter than most LCDs.

Color

Inaccurate color was a problem with older LCD monitors. Some monitors only feature 18-bit color (64 different levels of Red, Green, and Blue). Most modern monitors are now capable of true 24-bit color, but there is still an issue of color gamut or color range. Gamut refers to the range of colors a display device can actually reproduce. Even with 24-bit color (256 independent values of red, green, and blue), LCDs are just filtering the white light coming from behind the screen. Color accuracy is contingent on the ability of the backlight to produce a full color spectrum.

These two problems are addressed with Solarism Advanced Backlight Technology, discussed next.