20150623 - BenQ XL2730Z Blur Reduction vs CRT


TFT Central Review for the BenQ XL2730Z

The BenQ XL2730Z is one of the best 2560x1440 LCDs on the market. This display has a blur reduction mode which enables a strobe back-light (which only works properly with fixed 120Hz or 144Hz refresh rates). Its sharpness control also enables a reduction of sharpness, which can cut out a lot of the hard exact square pixel LCD feel, leaving an image which is more pleasing to look at. And it provides an exact pixel mode which instead of enlarging lower resolution modes, keeps a 1:1 mapping of input to output pixel, and draws the outside borders with black. So 1920x1080 still looks good, just doesn't fully fill the screen. Compared to other LCDs this display is awesome, and running with a 1000Hz gaming mouse at 144Hz with a strobe back-light is a wonderful experience in comparison to what most people are used to.

Compared to CRTs?
CRTs still easily surpass even these top of the line LCDs in quality. One of the core differences is that even the best LCDs cannot transition pixels fast enough for a true low persistence display. The BenQ for instance has frame cross-talk (seeing part of one or more frames). At the default "Area" setting (which controls the vertical position of minimal cross-talk), at 144Hz, up to 2 extra frames are partly visible at the top and bottom of the screen, however toward the center just 1 extra frame is partly visible. I have a feeling that variable cross-talk has to do with the fact that the back-light has to be a global strobe, but pixel rows are still scanned (changed) in the classic CRT scan order. So row to strobe timing is only best at one point on the screen. Likewise the LCD uses a column dither on the transition overdrive, even and odd pixel columns over-shoot then under-shoot respectively the transition such that the 2 column average is closer to the correct signal. The minimal 1 extra frame cross-talk is a product of the lack of ability to transition to the proper signal in one frame. This is quite distracting in comparison with the CRT. The CRT can easily offer low persistence at much lower frame rates without transition artifacts, while providing filtered pixels at a lower resolution while presenting a proper image instead of a lesson in cubism. So what would be 2560x1440x120Hz or 442 Mpix/s on the LCD, still does not compare to the quality of 1600x1200x76Hz or 146 Mpix/s on the CRT. And the CRT can use that 3x GPU performance for higher quality visuals.

Other Technology?
OLED isn't yet cost effective for consumers for desktop displays. For example, for $26K it is possible to get a Sony BVME250A - 25" Trimaster EL OLED Master Monitor. Sony's pro OLEDs seem to max out at 75Hz, not sure they even have a global strobe?

Prysm sells Laser Phosphor Display (LPD) Tiles: CRT like phosphor display driven instead by a laser. Each 4:3 aspect ratio tile is a near border-less 20"x15" (25" diagonal) with 320x240 or 427x320 resolution, scanned at 360 Hz according to their product sheet. I'm guessing these are also prohibitively expensive? If this is fixed 360 Hz scanning rate, that would also be a serious problem: a 90Hz input would be quad strobed, and that won't look good at all.