LCDs for graphics

I've been resisting actually doing this, because it seems like the industry changes so fast that it will all be irrelevant in a couple months, but I've had a few requests (from Ales & co.) to actually write all this stuff down. So here goes.

I actually don't know that much about LCD monitors -- I tried to figure out what I could by reading and looking at them. I can only tell you how to avoid the bad ones.

Specs & stats

Say you are comparing a bunch of LCD monitors, and you want to know (by looking at their spec sheets) which ones are good and which ones aren't. Here's a quick list of definitions and general features to look for.

1. Response time, otherwise known as "rise time+fall time": the amount of time it takes for a signal into the display to show up as full-intensity light and fade back out again.

   Good numbers are 25ms or less -- this is only 40 frames per second of animation, so there's still a way to go before LCDs can portray animation at CRT rates. Good CRTs use what are called "short persistence phosphors" (actually faster than a TV) and they can quite reasonably display 60fps+ animation. For most normal applications, 25ms is sufficient. If your display is "slow" scrolling text will be blurry, mouse movement will not be so great, etc.

   The other aspect of this is that most LCDs accept a signal at only 60Hz. I'm a little perfectionistic about this, but for cursor movement, I actually clock my CRT at 90 or 100Hz, because it makes the motion smoother, when you move the mouse or a window around.

2. Brightness, usually measured in cd/m^2 ("candelas per meter squared"), a unit also called "nits." Normal ranges are 200 nits or better, with better ones at 225 or better.

   Brightness influences contrast (and thus readability) but it's more a comfort thing -- most CRTs display low-100s in brightness, so an LCD of any kind will still be 2x brighter. (Interesting sidenote: some estimates say that for us to have usable emissive outdoor displays, we'll have to have displays capable of displaying 700-900 nits! An interesting alternative, as found on the NEC Versa Daylite, is a reflective display.)

3. Contrast, usually related to brightness, but not directly. This number measures the ratio of intensity between a white pixel and a black pixel -- how much contrast you'll see when reading text on-screen, for instance. Typical numbers for newer displays are 300:1 or better (some manufacturers have even started to claim 500:1!) CRTs, in comparison, are almost always <200:1 for non-Trinitron, and even Trinitrons just edge over 200:1.

1. DVI-I: I've found a noticeable difference betweeen digital (DVI-I) and analog inputs on my LCD (and it does a really nice job with the analog, just not the same level of clarity.) If you do casual work on the machine, you won't notice, but if you want to see pixel-level detail, get a card that supports DVI-I outputs. Many of the new Geforce3 cards do, including ones from Leadtek, Hercules, and a very occasional one from Visiontek (Visiontek makes whatever an OEM asks for, but most Visionteks will not have DVI-I outs.) I'm really impressed with the specs on the Radeon 8500, and the usual configuration has DVI-I for less than a Geforce3.

2. Color: Most LCDs have bad color. It's simply hard to calibrate them (even putting a sensor on the surface changes the image), and only a few manufacturers try. NEC claims to do sRGB calibration (sRGB is the 2.2-gamma standard from HP, Microsoft, and Adobe, standard in Photoshop 5 and Windows lately.) However, I have avoided NECs so far because they are slow (50ms response mostly). Give them a look, since they might have improved.

3. Color Part 2: Some LCDs have even worse color. In fact, I believe that some of the newer high-density displays (used in Dell laptops, manufactured by IBM?) have 6-bit-per-channel color. So this isn't really okay if you're doing a lot of color work. Make sure your display has real 24-bit color (most do now.)

4. Color Part 3: If you have a "bad" LCD, you can calibrate it! ColorVision (apparently bought by Pantone?) makes the Monitor Spyder, and they've just released an LCD version. Maybe if your company buys a lot of displays you could share this among multiple machines. It retails for $288 with PhotoCal software, and I have no idea what the ColorCal/PhotoCal distinction means (but you can pay more for more advanced software.)

5. MVA: The buzzword that means "wide-angle, bright, and fast" or "Multi-domain Vertical Alignment" depending on how technical the person you ask is. The newer displays have this or something equivalent. Don't buy a display without it.

6. Using one as a second monitor with DVI-I: If you want to use your LCD as a second monitor, you have a few options. Your first inclination might be to make it a second monitor. This is hard, if you want DVI-I. It's very hard to get DVI-I in a PCI slot (I think an old Matrox G200 with an add-on board might have it, but I couldn't find anything retail from ATI or NVIDIA.)

   To do this, you probably have to use one of the Matrox/NVIDIA/ATI ("TwinView / etc.") solutions that allow one large desktop instead (and hook up analog and DVI-I to one card.) Honestly, support under Windows is awful for two-monitors-on-one-card (it doesn't act like two displays should.) Even with the fixup software they give you (so dialogs don't come up in between the monitors, all the details are wrong -- maximized windows are the wrong size, etc.)

   Instead, I use the LCD as my primary (with a DVI-I AGP card), and have a separate Radeon PCI to drive my CRT. This is a much better combination. I would use analog for any other configuration.

I do a lot of pixel-level editing (think rectangles at pixel precision.) And I honestly didn't expect the LCD to be bad for this. But the truth is that, if you're working with color rectangles, it's next-to-impossible to actually select the edge of one without a lot of practice.

My old Viewsonic shadow mask (means "not Trinitron") CRT is a dream for this, because pixels line up, regardless of what color they are.

The reason this is different for LCDs: LCD elements are offset slightly based on color (exploited to good effect in Microsoft's Cleartype), but it makes pixel-level work strangely frustrating. I recommend you keep a boring old CRT on hand for color and pixel work.

Brands, thoughts

This is relatively uninformed. Based on specs, reading, and a little looking at CompUSA, etc. I could be very wrong.

I bought an LCD from Planar. This was about 6 months ago, and they had the best price/performance (industry-leading in most respects), so I got the 18" for about $1199. It turns out it's a little slow (35ms), the midtones are slightly yellow (I want to get a calibrator so bad!) That means some greens are yellow, but overall color temperature is pretty good. I'm really happy with it.

These guys are cool too -- they did displays for the military, and just recently started the desktop display gig. Right now, it looks like they have the first 19" 1600x1200 display for <$2000, and they also have a 19" 1280x1024 with an advertised 500:1 contrast ratio!

I almost bought one made by Viewsonic. They have good specs, but seem a little dimmer when I saw one in person. At the time, their 18" was much more expensive than the 17" (and still is, mostly.) Make sure to get an "MVA" display with digital inputs. I think they're still priced higher than Planar, but the color might be better.

Sony makes lots of displays, but the specs say they're dim. The industrial design rocks, though, so if that's first on your list, get one of these.

Samsung makes a lot of the components found in other displays. (I think they might be responsible for the Cinema Display from Apple.) Still, on the low-end, I've found them to be really dim and not too fast (I saw a 770TFT in person -- not impressive); their stuff doesn't compare to the MVA Viewsonic or Planar. But if you want a 24" display, there's nothing else available.

IBM also makes a lot of displays for other people. I think they manufacture the super high-resolution displays for Dell notebooks now. They also have the most insane display on the market (with 9.2 million pixels). Their displays are probably pretty good.

I'm sure there are many others. But that's what I know about. I enjoyed browsing around Dell's site and they have good prices too.