The Truth Behind 4:3 and 16:9 Formatting

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The Truth Behind 4:3 and 16:9 Formatting

Evan Powell, September 21, 2000

"There it is. Right there on the vendor's spec sheet. They say their projector has both 4:3 and 16:9 formats. It must be true, right? So how come ProjectorCentral's database lists it as having only 4:3?"

We get this question frequently. So it's time to clear up the mystery of aspect ratio formats. But in so doing, we will have to examine how some manufacturers design and market their projectors to get "both 4:3 and 16:9." And it's a story you probably won't like.

First things first...what does "aspect ratio" mean?

The term aspect ratio refers to the ratio of a picture's width to its height. If the aspect ratio of a picture were 1 to 1 (or 1:1), the width and height would be the same, and you'd have a square. Standard NTSC video has an aspect ratio of 4:3. That means for every four units of width, the picture will be three units high. HDTV standards call for an aspect ratio of 16:9, which describes a rectangle that is wider relative to its height than NTSC's 4:3.

In today's market, many projectors are being marketed with claims that they have both 4:3 and 16:9 aspect ratio formats. The is this possible if the internal displays have just one or the other? And what does it mean to the consumer?

Think physical displays for a moment

Let's start with some basics. LCD (Liquid Crystal Display) projectors make an image by shining light through glass LCD panels made up of thousands of little dots called pixels. Each pixel controls the amount of colored light it will project. Depending on the resolution of the projector, the projected image is produced by 1 to 4 million pixels.

DLP projectors make an image by bouncing light off a DMD chip (Digital Micromirror Device) that is populated with thousands of tiny mirrors which are the equivalent of LCD pixels. Each mirror is electronically adjusted to control the amount of colored light it reflects.

The physical array of pixels on an LCD panel or a DMD chip is fixed. At the moment, most DMDs and LCDs have a 4:3 aspect ratio with pixel arrays of 800 x 600 (SVGA) or 1,024 x 768 (XGA). Aspect ratios of 5:4 are also available to support 1280 x 1024 (SXGA) projectors.

At the moment, the Sony VPL-VW10HT is the only digital projector that has genuine 16:9 LCD panels. The fixed pixel array on its panels is 1,366 x 768. That is native XGA vertical resolution extended horizontally into a 16:9 aspect ratio.

Now at ProjectorCentral, when you see the aspect ratio specification for any projector in our database, it is reporting the physical array of pixels that exist on the panels or the chips. And there is always only one...they can't be physically both 4:3 and 16:9 at the same time, no matter what the vendor's spec sheet claims.

How do you get a 16:9 image format from 4:3 panels and chips?

Glad you asked. There is only one way to do it. And that is to mask off a horizontal portion of the 4:3 panel or chip at the top and/or bottom in order to create the 16:9 aspect ratio. By masking off a portion of the 4:3 display, you reduce the number of pixels that will be used to create the image. That means fewer lines of resolution. Furthermore, the masking also blocks a portion of the light that the projector is capable of delivering, so less light will reach the screen.

This has some important consequences. First, on a projector that operates like this, if you have a DVD that has both Pan-and-Scan (4:3) and Widescreen (16:9) format, you will always get better resolution and more light onto the screen with the Pan-and-Scan version. That's because Pan-and Scan uses the full 4:3 capability of the panels or chips. I know that will give some home theater buffs the willies, but it's the way it is.

Second, if you have a projector with a 4:3 physical display, you should use a screen that is also 4:3 in order to get the maximum performance from your projector when viewing 4:3 material. The best way to view 16:9 in this situation is to live with the black bars at top and bottom. If you want, you can get screens that will automatically raise/lower masking material that adjusts the viewable screen to 16:9 so that the black bars fall onto black masks and become invisible. The screen masking is then retracted when you switch to 4:3 sources. With this kind of set up, you can take maximum advantage of the native 4:3 display format in the projector.

Caution consumers! Be careful what you ask for; you might get it

Unfortunately, there is a strong perception among consumers that a 4:3 image should be smaller than 16:9. Not true. These are simply two different shapes of rectangles. Neither one is inherently "bigger" or "wider" than the other as either one can be projected at any size. Nevertheless, what many consumers want is this: they want a 4:3 image format in which to watch standard 4:3 source material. Then when switching to 16:9 they want the viewable image to widen noticeably. They have an emotional need to have "widescreen" look wider than 4:3. They are most happy to install a 16:9 screen, show a 4:3 image in the middle of it with black bars on both sides, then have the screen burst into full glory with breathtaking widescreen panorama when the source changes to 16:9.

You want it? You got it! Some manufacturers (not all do this) have devised a way to produce this phenomenon using physical 4:3 displays. And you probably won't like how it's done.

Actually, it's easy. The standard resolution of 4:3 video fits easily inside the resolution of todays data projectors. By limiting the resizing of the video, the projector is made to show a smaller 4:3 image than it is technically capable of. That image will have a black frame around it. When you switch to 16:9, the projector removes all or most of the vertical sides of the black frame, and just like magic you've got what looks like a bigger widescreen display. But the effect is produced by making the 4:3 image artificially small to begin with.

Cool right? Not necessarily. Consumers may pay dearly but unknowingly for this illusion. By masking off all four sides of a 4:3 display to create a smaller 4:3 image, part of the light is blocked. So you get a much dimmer 4:3 image than you would otherwise have. Furthermore, you have many fewer pixels to make the image so both horizontal and vertical resolution gets hammered. And the pixel structure itself becomes more visible for any screen size as you use your zoom lens to fill your screen with the reduced resolution image. None of this is good news.

We don't want to pick on any vendor in particular since a number of them do this. But take for example the Davis Cinema One. This machine has a physical DMD chip resolution of 800 x 600. With data sources, the image is shown in full 800 x 600 which is just fine. But switch to a video source in 4:3 and what you do get? A black frame mask is thrown around the edge of the chip and the actual video image is produced using a reduced active pixel matrix of 690 x 532.

The result: instead of 480,000 pixels on the screen (800 x 600), you get a mere 367,080 (690 x 532). So you lose 112,920 pixels, or 23.5% of the display's resolution, and 23.5% of the projector's light output. To top it off, the pixel matrix itself is a little more visible than it needs to be if you zoom the image to make up for the lost size. And the ONLY benefit to this sacrifice in 4:3 performance is the emotionally satisfying experience of seeing your 16:9 material open up and look a little wider than your 4:3.

The manufacturers that do this are trying to address the consumer's demand for projectors that make 16:9 look wider than 4:3. And as long as there are consumers for whom this is a paramount concern, vendors will build projectors to deliver that illusion. When a vendor's spec sheet touts both "4:3 and 16:9" aspect ratios, take caution. This may be one of the machines that produces a big 16:9 image by reducing 4:3 quality. If so, think about whether that's something you really want.

(NOTE: To clarify, all native 4:3 LCD and DLP projectors are able to produce both 4:3 and 16:9 images. The discussion here is focused just on those machines that create the illusion of the 16:9 being wider than the 4:3, which is an unnatural act for a machine with a physical 4:3 display.)

Sony's obvious but unique solution

Virtually every maker of digital projectors uses 4:3 physical displays in SVGA and XGA resolution. Almost all of Sony's products are 4:3 as well. However, Sony has built a unique 16:9 LCD panel (1,366 x 768) into the VPL-VW10HT, making it an exception to the rule. When you start with a physical display of 16:9, it is natural to present 4:3 by using black bars to mask the sides. Thus on this projector 4:3 material is shown in native XGA resolution (1,024 x 768) without any compromise in resolution. And when you switch to 16:9, the screen size widens to take full advantage of the native capability of the display.

This is not to say that the Sony VPL-VW10HT is necessarily the best home theater performer in its price range. There are several native 4:3 machines that can deliver more exciting video for the money in today's market. However, the Sony product commands a lot of attention among home theater buyers. And deservedly so since Sony is the only vendor to try to address the consumer's desire for a bigger, wider 16:9 image without compromising the integrity of 4:3 performance.

Know what you want and pick your projector carefully...

Some products do the four-way masking of 4:3 video and there's no way around it. Many don't do this kind of masking at all--they display maximum resolution 4:3, and let 16:9 material display at the same physical width as 4:3.

The question is this: what do you really want? If you want 16:9 to look wider than 4:3 when you switch back and forth, you need to (a) get one of the projectors that are artificially rigged to deliver that experience, or (b) get the Sony VPL-VW10HT which has a unique technical advantage in being able to do this. If you are concerned more about overall resolution, picture quality and maximum performance, look to the projectors that deliver 4:3 in full format and forego the illusion of a wider 16:9 image.

Most importantly, educate yourself about your options. There are hoards of projector sales people at your local "Buster's Big Screen Emporium" that don't have a clue how these products work. But they can press a button that brings up a pre-canned demo showing you the difference between paltry 4:3 and "REAL" widescreen performance! The uneducated consumer is their lawful prey.

(06/19/19 - 04:00 PM PST)
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