Moving onto the LL-171A-B TFT panel, this has a native resolution of 1,280 x 1,024 pixels. It’s also capable of displaying 16.19 million colours which is more than the eye can perceive, but is a number that gives us a clue to its inner workings.
To explain, a monitor’s 8-bit controller can produce 256 shades per RGB sub-pixel, which gives rise to 16.7million colours per pixel (256 x 256 x 256 = 16,777,216). But here we’re talking about 16.19million colours.
The reason for this lower figure is because the Sharp LL-171A-B uses a 6-bit controller with FRC (Frame Rate Control). Basically FRC is a way of “filling in the colours” by rapidly switching the pixels between dark and light shades every time a screen image is displayed. This transition between light and dark effectively “mixes” the shades in order to produces the intermediate ones that are missing.
Now because a 6-bit controller (with the FRC) can only hold up to 253 shades per RGB sub-pixel the colour is limited to 16.19miliion (253 x 253 x 253 =16,194,277). Basically what all this means is that the LL-171A-B (as well as many LCDs from other manufacturers) is using, to use the term very loosely, “dithering” in order to increase its colour gamut.
Now this may put of some users, but results from the Displaymate tests and subjective analysis of our test images and DVD movie revealed that this monitor is quite capable. Even with its analogue signal and “temporal dithering” the quality of the colour scales was evenly stepped with only slight compression at the highlight ends and dark ends of the colour and greyscales. There were signs of some banding steps in the 256 greyscales, but it wasn’t excessive. Our test images appeared very bright in spite of the pretty standard 250cd/m2 brightness rating, plus there was enough contrast to bring out details in areas of shadow.
Likewise, the DVD movie looked good too, and as far as I could tell motion smearing on this 20ms response time monitor was hardly noticeable. Skin tones also looked realistic although some tweaking was needed to bring a slight reddish tinge into check. The only real downer was the vertical viewing angle, where the illumination fell off rapidly beyond 45 degrees.
Despite the limited stand, the lack of a DVI port, and a few minor hiccups in the display tests, the Sharp LL-171A-B’s price makes it quite competitive. The is not a true 8-bit monitor, but I’ve seen those that are, perform worse – a sensible choice for those after a display that looks good, feels solid, performs satisfactorily, and won’t break the bank.