Why do large displays have so few pixels?

Michael Geary | Wed, 2005-07-20 01:05
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Engadget loves big LCD monitors, and today they are reporting on the Philips 190PX and 200W6.

At 19” and 20.1” diagonal size, these displays are big, all right, but so are the pixels.

The 200W6 has 1680x1050 pixels, or 99 pixels per inch (measuring horizontally or vertically).

The 190PX has 1280x1024 pixels, or 86 pixels per inch. Those are huge, coarse pixels.

For comparison, my ThinkPad A30p has 1600x1200 pixels on a 15” panel, or 133 pixels per inch. That’s 1.5 times the linear density and 2.4 times the areal density of the 190PX.

Even my old ThinkPad 600 has a higher pixel density than the 190px, with 1024x768 pixels on a 13.3” panel giving 96 pixels per inch.

Why are small pixels better than large ones? The same reason that a 600 dpi (dots per inch) laser printer is better than an old 144 dpi dot matrix printer. If you print text at the same physical size on both printers, the 600 dpi gives you much better print quality than the 144 dpi.

The same is true for displays, if you adjust the text size to be about the same physical size instead of just letting the text get smaller because the pixels are smaller. On the A30p, I run Windows in 120 dpi mode instead of the default 96 dpi. In Windows XP, this setting is hidden away in the Display control panel, Settings tab, Advanced button. (It’s possible to use a custom pixel size so that I could match my 133 pixels per inch resolution, but not all programs work well at custom resolutions, and 120 dpi is close enough.)

By running in this display mode, I get text that is about the same physical size as text on a coarser display in the default 96 dpi mode. But there are many more pixels making up each character, giving much better looking and more readable text—especially with ClearType. Those extra pixels really let ClearType do its job, even to the point where serif text is good looking and readable. Serif text is notorious for being unreadable at small sizes on a computer display, and the problem is simply too few pixels to render the serifs cleanly. With more pixels per character and ClearType, the picture changes completely and even relatively small font sizes look good and are easy to read.

By comparison, when I look at a display like the 190P6, the text is coarse and grainy. Of course, I could run any display in 120 dpi mode, so the text would use the same number of pixels as on my ThinkPad, but 120 dpi mode on an 86 dpi display makes everything huge.

To get the same pixel density as my ThinkPad A30p, a 19” display would need to have about 2000x1500 pixels. Now THAT would be a display. Let me know when somebody makes one!

Submitted by Antonio (not verified) on Tue, 2006-01-17 10:36.

Ideally I agree with you that higher pixel per inch would be better, but consider that still today many web sites are designed for 800x600 with small fixed font size and many windows applications are not displayed correctly with increased font dpi (typically text will be truncated). On a high dpi monitor these applications would be very eye fatiguing or unreadable. Consider also the laptop is closer to you eye than a big monitor would typically be. On the contrary some applications like acrobat reader and hires photo editing would be great with high dpi (or ppi?) monitor The problem is that windows and the browser have a very poor implementation of scalable font and resolution indipendent concept, Ms developers should maybe take some classes at Adobe. Hope it will be better with windows vista. Currently I can’t decide if to buy a 19” @ 1280 res or a 20” @ 1600 res because of this problem.

Submitted by Zach (not verified) on Wed, 2005-07-20 16:51.

Good point but seeing as most games are run at 1024x728 for most people right now (on computers), I doubt many people would buy a monitor that dense. Plus it’s easier and cheaper to build a monitor that is 15” than its than one one that is 20”. Less waste.

So good point but not economical. I agree but the price for such high quality device to build and support (resolution costs processing power) is astomnomical. The cost outwieghs the value.

Although Viewsonic right now is developing a high densisty lcd for professionals. Its at least 19” and has 4x the pixel density as normal lcds. Like I’m talking monstor resolution. Saw it on slashdot while back. I think the cost was around $5K. Pretty spendy if you ask me.

What I’m trying to do right now is find a good display for a media center without sacrificing resolution. That means finding a display that is large enough for the living room but is sharp enough for text. Any ideas?

Submitted by Dave Land (not verified) on Wed, 2005-08-03 08:27.

I think what you’re looking for is ViewSonic’s VP2290b widescreen 22.2” digital LCD, featuring a whopping 8.35 megapixels (that’s 3840x2400 pixels) at 204 PPI. That ought to about cover it. On sale now at (http://store.yahoo.com/shopmiracle/vp2290b.html) for just $4,999 ($7,999 list). Froogle could probably find it a couple of shekels cheaper.

IBM counters with their T221 16 x 10 Aspect Ratio, 22.2-Inch Diagonal 3840 x 2400 Pixel LCD Color Monitor, checking in around $8,300 list. It’s apparently been around for a couple of years.

Down-res a little bit to Trident Displays’ IDP2800SQ 2k x 2k Display for Air Traffic Control (http://www.tridentdisplays.co.uk/monitors/2k2k/airtraffic_control.html). That one will probably set you back somewhere in the low 5 digits, but hey, you’re the big shot with the two-dot-two-letter domain name!