The Devil’s Advocate – Apple Display Dyslexia

Why is Apple losing the resolution race to Dell? When it comes to laptops, PowerBook users are always left whimpering like puppies for just a few more pixels of resolution when they look at their PC counterparts. Case in point, Dell and others have been offering laptops with 1600×1200 resolutions (1.9 Megapixel) for a long time, which is more resolution than offered by Apple’s original 22" Cinema Display. Not too long ago, Dell added a model with a 15.4" display showing 1920×1200 pixels (2.3 Megapixels), which is the same resolution offered by Apple’s 23" HD Cinema Display. Only relatively recently has Apple increased the resolution of its 15" PowerBook to 1280×854 (1.1 Megapixel) and the 17" PowerBook sports a relatively anemic resolution of 1440×900 (1.3 Megapixels). Sadly, the same disparity now applies for desktops. IBM and others have been offering QUXGA resolution displays (i.e., 3840×2400 pixels) for some time.

Ah, I can see the comments coming. "Why would I ever want that many pixels on my computer?" Usually asked by the same guy who is lusting after a high definition television set. The basic answer is more pixels equal more resolution. In general, higher resolution is almost always better; it generally provides a sharper, cleaner, clearer picture. That’s why you pay more for an HD television or a higher megapixel count digital/video camera.

There is one wrinkle that many apologists cling to in that User Interfaces (UIs) don’t scale well to higher resolution displays. However, Aqua with its scaling and beautiful huge icons attest to the current practical invalidity of such arguments. Actually, to some extent, Apple is already operating on very high definition displays; the partial pixel rendering of Quartz basically triples the resolution of current screens by using an LCD’s red-green-blue sub-pixels.

Playing a good hand poorly, again

Although Apple is the only major operating system provider to include a device-independent imaging system, in some ways, its implementation is more stunted than Microsoft Window’s imaging model. How could this be when the Macintosh is considered to be "the" machine to use in the design world?

Before I get into how Microsoft is better in this regard, let’s look at Apple’s imaging model, Quartz. Apple’s screen imaging system is based on an independent variant of Adobe’s Portable Document Format (PDF). Of course, the great advantage to a PDF (or Postscript, which was PDF’s precursor) imaging model is that the same code used to draw the screen can be used to raster to almost any output device; such rasterization takes advantage of the output device’s maximum resolution, which is often higher than screen resolution.

This works well because PDF rasterization engines are made aware of the pixel density of a particular output device. For example, if you have a 600 dot per inch (dpi), Postscript, monochrome laser printer, a Printer Page Description (PPD) file describes the abilities of the printer, including things like the margins of the printer, its print density (e.g., 600 dpi), color abilities (e.g., 1 bit per pixel, i.e., monochrome), etc. With a PPD, the rasterization engine for a particular output device can take a PDF file and "map" it. A grossly simplified explanation of how such mapping works is that the PDF document provides mathematical points in space which may be processed based on the resolution of an output device.

Perhaps an example using two printers will make the advantages of resolution independent rendering intuitive and apparent. Most people realize that buying a printer with a higher resolution (or more accurately, having the greatest information density) improves the quality of print-outs. So 300 dpi printers use less pixels to make up an image than 600 dpi printers, and so, the results look worse.

The printing example In a simple case of a document describing a single 1" line between points (a) and (b), the instructions might be something akin to a starting point at 1" in and 1" up from the bottom of a letter-sized piece of paper (point (a)), and an end point at 1" in and 2" up from the bottom of the paper (point (b)). In such a case, if your output device is a 300 dpi device, it will fill in 300 dots between these points (a) and (b) to form a vertical, 1" line. If your output device is a 600 dpi laser printer, it will fill in 600 pixels to make the very same line. In both cases, the printers will make a 1" long line, however, the latter will do so at a higher resolution, i.e., it will use 600 dots instead of 300 dots to draw the line.

If it were only the case for OS X and Apple screens. OS X is too stupid to realize that drawing a 1" line on a 14" iBook takes less dots than drawing a 1" line on a 12" iBook.

Considering the might of Apple’s Quartz, and all the extra cycles being sapped to render its eye-candy, it’s rather inexplicable that Apple hasn’t put in functionality to take advantage of Quartz’s resolution independence.

Since Apple’s display PDF already supports device independent printing, and is used for screen display, Apple should upgrade Quartz to support resolution independence for its screens. Then Apple could use very high resolution screens. For example, Apple could offer the same 15.4" 147 dpi (1920×1200 pixel) screen that Dell uses instead of its 15.2" 101 dpi (1280×854 pixel) screen in its PowerBook. Actually, it is likely that Apple has not chosen to use a higher resolution screen in its machines simply because it has not taken advantage of Quartz’s device resolution independence.

One step behind the competition

Just check out how far behind Apple’s equipment is with regard to high-resolution screens:

Output Device	Diagonal (Output Size)	Vertical	Horizontal	Square Inches	Pixels Per Inch (PPI)	Maximum Horizontal Pixels	Maximum Vertical Pixels	Total Elements (a.k.a. MegaPixels (MP))	Depth Per Pixel	Total Surface Data (Mega Bytes (MB))	Data Per Inch Square (Kilo Bytes (KB))
Apple Imagewriter	15.3	8.0	13.0	104.0	144	1152	1872	2.2	1	0.3	2.5
Apple Laserwriter	15.9	8.2	13.6	111.5	300	2460	4080	10.0	1	1.2	11.0
Apple Imagewriter LQ	19.6	16.5	10.5	173.3	216	3564	2268	8.1	3	2.9	17.1
iBook Tangerine	12.1	7.3	9.7	70.3	83	800	600	0.5	24	1.4	20.0
Cinema Display	22.0	11.9	18.5	219.8	86	1600	1024	1.6	24	4.7	21.8
iBook 14"	14.1	8.5	11.3	95.4	91	1024	768	0.8	24	2.3	24.1
PowerBook Titanium	15.2	8.4	12.6	106.6	91	1152	768	0.9	24	2.5	24.3
24" LCD	24.0	12.7	20.4	258.9	94	1920	1200	2.3	24	6.6	26.1
Apple 23" Cinema Display	23.0	12.2	19.5	237.8	98	1920	1200	2.3	24	6.6	28.4
PowerBook 17"	17.0	9.0	14.4	129.9	100	1440	900	1.3	24	3.7	29.2
21" CRT	20.0	12.0	16.0	192.0	100	1600	1200	1.9	24	5.5	29.3
PowerBook 15" Aluminum	15.2	8.4	12.6	106.7	101	1280	854	1.1	24	3.1	30.0
iBook Ice 12"	12.1	7.3	9.7	70.3	106	1024	768	0.8	24	2.3	32.8
24" CRT	23.0	12.2	19.5	237.8	118	2304	1440	3.3	24	9.5	40.9
HP Laser Jet 4000	15.9	8.2	13.6	111.5	600	4920	8160	40.1	1	4.8	43.9
21" CRT	20.0	12.0	16.0	192.0	128	2048	1536	3.1	24	9.0	48.0
Dell Ultra XGA+	15.0	9.0	12.0	108.0	133	1600	1200	1.9	24	5.5	52.1
Dell Ultra Wide XGA+	15.4	8.2	13.1	106.6	147	1920	1200	2.3	24	6.6	63.3
IBM T221 22" QUXGA	22.2	11.8	18.8	221.5	204	3840	2400	9.2	24	26.4	121.9
Tektronix 740 Plus	15.9	8.2	13.6	111.5	1200	9840	16320	160.6	2	38.3	351.6
Tektronix 790	21.3	12.6	17.2	216.7	600	7560	10320	78.0	8	74.4	351.6
Fuji Pictrography 4000	21.6	12.0	18.0	216.0	400	4800	7200	34.6	24	98.9	468.8

You can see that Dell’s Ultra Wide XGA+ screen has over twice the informational density of the PowerBook 15" and the IBM T221 22" QUXGA screen has over four times the informational density of the Apple 23" Cinema Display. Basically that means things will look much sharper on the Dell or IBM.

Because Apple has no facility to take advantage of varying screen resolutions, you may notice, depending on the monitor you sit in front of, that user interface (UI) elements have varying sizes. Scrollers, icons, window bars, etc. are much smaller on a 12" iBook than on the 14" iBook screen. They both have the same number of pixels, i.e., 1024×768, but the 14" iBook actually has lower pixel density (see the chart above to compare the various pixel/informational densities).

One 1" equals 1" with Windows and pot-luck with OS X

The variances in UI element size only get worse when we start talking about desktop models. In essence, Mac OS X is too stupid to figure out how to draw a 1" line in one 1" of physical space on a computer screen, while Microsoft Windows actually handles such scenarios with aplomb.

Windows provides a preference panel where you tell the operating system the resolution of your computer screen. It even provides a relatively intuitive interface as shown above. You just grab a real ruler, put it up to your screen and drag the screen ruler until its hash marks line up with your real-world ruler. After that, Windows handles the rest. Windows re-rasters all UI widgets to a new resolution, and Windows applications and documents take advantage of this information. If you put a piece of paper up to your screen, under Windows, pleasantly, you discover that the physical document lines up with the screen version. As of 1995, Windows has been able to raster screen information onto a screen accurately. We still cannot on the Mac.

Now all is not rosey in the Windows world. The algorithms it uses to map the screen to the proper resolution are not the greatest. In particular, icon and bit map scaling is prone to ugly pixelization artifacts. To be sure this isn’t a linear issue. Using more pixel density is not a simple matter of blowing up existing images — that would accomplish nothing — but rather a matter of complex re-rastering of screen elements.

The great thing about Mac OS X is that Quartz already can handle and deal with all of this complexity. Nonetheless, when going to higher resolution settings, the overall effect is that the screen looks sharper.

Seeing is believing

OS X’s Quartz scales bit maps much better than Windows, so the bitmap artifact issue that is often raised in such discussions is largely moot. OS X re-rasters bitmaps that well. To see a somewhat concrete example of this, try the following. Make sure you have enough icons in the Dock so it stretches from one edge of your screen to another. Then reset your video resolution from higher to lower and back again (e.g., from 1024 by 768 pixels to 640 by 480 pixels). Notice that the physical size of the dock stays constant, but the resolution improves and generates a sharper image at a higher resolution.

We get a little glimpse of how great it is to have higher resolutions screens and device independent imaging with the above Dock examples. If you look at Figure 1 you can make out the "Mar" in the iCal icon relatively easily. In Figure 4, you see the dock is rastered at a lower resolution and it’s more difficulty to read the "Mar." The Dock scales great. The problem is that the rest of the OS X user interface is not resolution independent like the Dock.

Lowering resolution to increase font size is dumb

If more resolution is better, then why doesn’t everyone use higher resolution screens, especially under Windows where you can specify the screen resolution? Most people simply don’t know the feature exists in Windows. For whatever reason, Microsoft does not use the Windows screen descriptors to automatically set the system to the proper resolution for an attached screen.

That’s the reason why you see many users, particularly those that have difficulty reading, setting their screen resolution to 800 x 600 or even 640 x 480 pixels. They do so, just to get the font size to be legible. Of course this makes little sense when they have screens capable of displaying 1280×1024 pixels, 1600×1200 pixels, or higher. Doing so is akin to cutting your nose off to spite yourself. Specifying the proper screen resolution properties in the operating system would not only make the fonts the proper size, but would raster those fonts and every other screen element at a higher resolution, thereby making everything more legible.

In theory, but not in practice

Here, Apple has a potential advantage over Microsoft. Apple’s rastering technology is simply superior to Microsoft’s. Apple could provide a far more sophisticated system. For example, on multi-display systems, Apple could render windows and data at the proper resolution for each screen. That way if you have a 204 dpi IBM LCD screen and a 100 dpi PowerBook screen, OS X would raster things properly on the fly between screens. That way when you dragged a 4"x5" image between screens, it would remain 4"x5" instead going from poster size to stamp size.

Unfortunately, Apple is simply choosing not to use Quartz to its advantage; and unexploited, it doesn’t matter if Apple "could" do it better; the reality is it doesn’t do it at all. One wonders how long it will take for Apple to reach screen resolution parity on its computers when it still has yet to reach parity with Windows in enabling variable screen densities in its operating system.

Quite honestly, without such a screen resolution setting, high resolution displays like IBM’s T221 22" QUXGA screens are unusable in OS X. Even if you could find a Mac graphics card to support such a monitor, at 3840 x 2400 pixels, an Aqua scroll bar would measure less than 1/32", which is too small a click target for most users.

The bottom line is the lack of a UI resolution setting is stunting both Apple’s hardware and operating system. The inability to render the UI at multiple resolutions prevents Apple from considering higher density screens. Realistically, such displays, will remain unusable and out of reach on the Mac until Apple implements this feature. Considering that the graphics market is important for Apple, one can only hope Apple will finally bring true WYSIWYG functionality to its platform sometime in 2004, only 9 years behind Windows.