On Display

By Jerry Pournelle

September 12, 2005

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Column 301 (Continued from the Previous Week)

Why Susie Hates Her New Monitor

As Dr. Huth said, CRTs degrade over time; the 19-inch NEC MultiSync I've stared into for the last seven years on my primary writing machine does not have the same color as when it started. LCDs don't drift as much, though the Cold Cathode Fluorescent Lamps (CCFLs) used to backlight them lose brightness over time. Meanwhile, LCD resolutions are increasing, both in absolute numbers (screens are increasing in size) and density (pixels per square inch). That's great, but it comes with certain tradeoffs, particularly on Windows: icons, like on Word's "Standard" toolbar, or the Windows desktop, are a fixed number of pixels in size. If the resolution increases, then the icon's size on the screen decreases. Yes, you can switch to "large icons" on Windows, but that only goes so far.

This problem doesn't affect vector images, at least not as much. Text, like in Word as I type, will only look better as resolution increases; Windows (and the Mac) scale the letterforms on the fly, so more bits are used to display them. If you're curious how fonts are described, go into the fonts control panel and open, say, "Times New Roman (TrueType)." You'll see specific "hinted" fonts at even sizes, like 12, 18 and 24 points. Anything in-between the hinted sizes is rendered mathematically. That's the most obvious when you zoom to a prime-number size, because the math doesn't come out even and letter edges look a little ragged.

The bitmap-image problem is most evident on extremely high-resolution displays. I was reminded of this at SIGGRAPH, where the IBM T221 "Big Bertha" display finally came into its own, merely three years after its introduction. This 22.2-inch wide LCD has a native resolution of 3840 by 2400, making it the highest resolution desktop display built to date. Ironically, this display (and the equivalent ViewSonic VP2290b) so far outstripped the state-of-the-art in video cards that only today, after it's been discontinued, can either NVIDIA or ATI do it justice.

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