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Subject: Aspect Ratios, Scanlines and Modern Displays
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A couple of years ago I got into a fiery argument on a forum with someone who thought he knew the 'right way' to display a video game, and all other ways were simply wrong 'cause the designers wouldn't want it that way.. He went through great lengths to add screen curvature, scanlines and even reflections of overhead lights to try and replicate the appearance of gaming on a CRT monitor.
He was obviously deranged.
Still, there was a hint of fact in there: modern fixed-resolution displays don't do a very good job of displaying older games. No matter how they're displayed, some changes are made and compromises have to be accepted.
First, a crash-course in TVs:
Older CRTs (the big, heavy, glass tube-style TVs (basically everything pre-LCD and pre-plasma)) use a firehose approach to drawing images on the screen. Imagine three big, sweaty firemen spraying their three hoses back and forth along the back of a giant drive-in movie screen that's been painted with red, green or blue stripes. There's a grid in between the firemen and the screen, so that each fireman's hose will only spray one colour, the grid prevents their stream from hitting any other colour. They spray in sync: special signals tell them when to start again on the other side of the screen, and when to start at the top. For their entire working lives they zigzag right and left, from top to bottom, over and over and over.
Basically, that's how the old TVs worked: three electron guns sprayed electrons at different coloured phosphors, which would light up based on the intensity of the beam. It was never very accurate: sometimes the beams would drift out of alignment, failing components caused all kinds of undesired visual artifacts, and even the Earth's magnetic field would wreak havoc on the display.
For all these problems, they had some capabilities that the modern fixed-resolution LCDs and plasmas can't match. While modern displays have caught up or surpassed CRTs in many respects, in two specific criteria the old units are better than modern displays: image scaling and refresh speed. I'm going to focus on the former, for now.
Generally speaking, older screens used a 4:3 horizontal:vertical aspect ratio. In other words, the screen was one third wider than it was tall. Most modern TVs are widescreen, which presents a simple problem: what do you do when you have an image 1/3 wider than its height, on a TV that's nearly twice as wide as its height? If you leave it the same ratio, it'll have unused black space on the sides (fig. 1). If you zoom in, you lose the top and bottom of the image (fig. 2), and if you stretch it horizontally, it looks a bit funny (see below).
![[Image: /grafx/games/ASPECT-small-or-zoom.png]](/grafx/games/ASPECT-small-or-zoom.png "/grafx/games/ASPECT-small-or-zoom.png")
LCDs and plasmas (and DLP projectors) are fixed resolution displays, and they don't scale images well. Photographs and TV shows and movies look just great when you zoom in or stretch them a little. They use a technique called resampling to create an image that's not quite entirely unlike the original, but bigger.
Pixels, however, are hard-edged pointy little things which look really terrible if you stretch them at all. Resampling a pixel makes it blurry, and half the appeal of pixel art is its clarity... Even if you're not a pixel-art fan, they often look out of focus. Many people won't notice, or won't care, and they might as well stop reading here.
The alternative method of making them larger is hard-scaling. Rather than stretching them, you simply duplicate one horizontal or vertical row at a time until the proper size is reached. The problem with this approach is... Well, it's really ugly. The only appealing option on a fixed resolution display is to hard-scale an integer value: 2x, 3x, 4x etc. Rarely though will this ever fit your screen without leaving gaps, and filling the gaps is what CRTs do best.
![[Image: /grafx/games/ASPECT-scaling.png]](/grafx/games/ASPECT-scaling.png "/grafx/games/ASPECT-scaling.png")
If you resample pixel art, you get unattractive blur.
If you don't resample, you get really ugly, hard pixels.
It's never easy to scale things on a fixed-resolution display.
CRTs had a little secret skill: when an image needed to be stretched vertically, the firehoses just moved from top to bottom a little quickerr, adding just a tiny fraction of a millimeter between each sweep of the beams. If you needed to fill the horizontal screenspace with a smaller image, you just updated the signal a little slower, so as the beams swept side to size (you couldn't change this speed) a pixel might cross one red phosphor, or two, or maybe two and a bit. The thing is, a CRT's never really looked pixel-perfect to start, so a little bit of futzing with the image was rarely noticed by the user.
![[Image: /grafx/games/ASPECT-scanlines.png]](/grafx/games/ASPECT-scanlines.png "/grafx/games/ASPECT-scanlines.png")
Richter has undergone massive changes in size.
Smaller changes are virtually unnoticable.
Arcade games, consoles and even computers often took advantage of this, and created a RAM- and CPU-friendly smaller image that would be stretched out to fill the screen with no more effort than a tweak of the synchronization signals. The vast majority of SuperNES games created a 256-horizontal-pixel image, but TVs felt most comfortable displaying a 320-pixel image. No one playing SuperNES back in the day ever complained about this 25% difference in size, they simply never noticed.
![[Image: /grafx/games/ASPECT-25pc.png]](/grafx/games/ASPECT-25pc.png "/grafx/games/ASPECT-25pc.png")
It was very common. Almost all NES and SuperNES games did this. Most PC Engine games did too, and many MegaDrive games. In the arcade, Ghosts n Goblins used this effect. The sequel, Ghouls n Ghosts, used a higher-resolution screen. Even though the firehoses were spraying at the same speed, more pixels were pumped out for every line in the sequel, ultimately resulting in more detail.
On the SuperNES, games like Super Ghouls n Ghosts and R-Type II had to re-draw the arcade sprites to be 20% smaller, so when stretched on the SNES TV screen, they'd look right to the player. If you didn't know it was being done, you'd likely never notice. I have to assure you, on a CRT it's just invisible, unlike how these examples appear on your LCD monitor.
![[Image: /grafx/games/ASPECT-stretching.png]](/grafx/games/ASPECT-stretching.png "/grafx/games/ASPECT-stretching.png")
Left: Super NES. Center: SNES stretched. Right: Arcade.
In the images above, you can see how the SuperNES sprites are nearly identical to the arcade. They're a little bit blurry, but you'd never notice the difference on a CRT. This little visual trickery confers an immediate 20% savings in required storage space, which is a very valuable savings in the days of cartridges.
![[Image: http://nfggames.com/system/arcade/special.php/b-d/bp-5/y-kof97/z-10/x-What?/.png]](http://nfggames.com/system/arcade/special.php/b-d/bp-5/y-kof97/z-10/x-What?/.png "http://nfggames.com/system/arcade/special.php/b-d/bp-5/y-kof97/z-10/x-What?/.png")
![[Image: /grafx/games/ASPECT-scanlines-1.png]](/grafx/games/ASPECT-scanlines-1.png "/grafx/games/ASPECT-scanlines-1.png")
![[Image: /grafx/games/ASPECT-scanlines-2.png]](/grafx/games/ASPECT-scanlines-2.png "/grafx/games/ASPECT-scanlines-2.png")
This post was edited on 2009-04-20, 13:15 by ![[Image: /grafx/games/ASPECT-compress.png]](/grafx/games/ASPECT-compress.png "/grafx/games/ASPECT-compress.png")
![[Image: /grafx/games/ASPECT-splatterhouse.png]](/grafx/games/ASPECT-splatterhouse.png "/grafx/games/ASPECT-splatterhouse.png")
the neo gives like a 59Hz signal and modern TVs cant handle that properly 
![[Image: /grafx/XboxMag.jpg]](/grafx/XboxMag.jpg "/grafx/XboxMag.jpg")
it kicks LCD and plasma into the past at standard def viewing