Talk:Aspect ratio

All Theory
This is all theory and unsourced. You can't use this for evidence of anything. 68.126.1.159 22:38, 14 June 2007 (UTC)

Latest diagrams
The latest diagrams seem somewhat confused, Image:Aspect diagram.png, for example. The point is that in the 320x200 VGA mode, pixels aren't square: 320x200 should fill the whole screen, even though the sides of the monitor are always in a 4:3 ratio, the actual screen resolution that the game outputs to is a 16:10 ratio. If you run Vanilla Doom and take a screenshot, viewing that screenshot back in Windows in 1024x768 resolution, the screenshot will appear squashed.

I don't know if perhaps I'm not understanding the purpose of this diagram. I might not be seeing the point you're trying to make. The whole point of the aspect ratio thing is that when you run in 320x200, there shouldn't be any black borders at the top and bottom of the screen: it should fill the whole screen. Fraggle 23:43, 17 June 2007 (UTC)
 * Yeah, I'm not talking about that specifically, just aspect ratios in general. The first diagram is to clarify what I think you said about Doom 95, since it's not worded well. The second is to demonstrate how some ports don't correctly manage different aspects. Like I was saying about Skulltag, they don't swap between 4:3 and 16:10 correctly. Which one is right isn't as important as the fact that one of them has to be wrong. Tangent 23:48, 17 June 2007 (UTC)
 * I think you've confused the issue by talking about widescreen modes. Can we stick to discussion of "normal" (4:3 size ratio) monitors? Or is the entire problem you're having caused by your use of a widescreen monitor? Fraggle 00:08, 18 June 2007 (UTC)

From first principles
I'm going to lay out my entire point of view here, because I really think we're at crossed wavelengths and need to better understand each others' points.

Almost all monitors have a 4:3 ratio between the screen's physical width and height (although this is not true with a widescreen monitor). Vanilla Doom runs in the VGA 320x200 screen mode. So there is a difference between the 16:10 ratio of the screen mode and the 4:3 physical ratio of the monitor. You can solve this problem in two ways:


 * 1) Scale the image up to the screen, leaving black borders at the top and the bottom of the screen ("letterboxing"). If you do this, the pixels stay square.
 * 2) Stretch the image vertically to fill the entire screen. If you do this, the pixels are no longer square, as they are now each taller than they are wide.

I am specifically stating that, as far as Doom is concerned, the second of these is the correct thing to do, because the graphics appear to have been designed for the VGA cards of that era, and this is what those cards did. If you do the first option, and use borders, the screen image will appear squashed (like in Image:Aspect-ratio-titlepic.png). Some modern graphics cards only support 4:3 screen modes through the borders method: this is why I included the section on choosing a video card, because if you want Doom to run as it was natively designed to run (without borders), then you want a card that does the second option, rather than the first.

What aspect ratio correction does is to perform the stretching in software, because we can no longer rely on consistent behaviour across graphics cards and monitors. The game runs in a 4:3 screen mode (like 320x240, 640x480) and is stretched in software to appear as it would have originally appeared on a DOS VGA machine in 1993.

If you're going to run on a widescreen monitor, it becomes more complicated. Now, you effectively have extra space at the left and the right sides of the screens. In this case, you can either:


 * 1) Display black borders at the left and right side of the screen (ie. not use the extra space)
 * 2) Expand the rendered field of view so that you can horizontally see more.

Now, you can shoot yourself in the foot here, because there is another option: you can stretch the screen out horizontally to fill the extra space. But then you've screwed the aspect ratio again and squashed the screen again (back to looking like Image:Aspect-ratio-titlepic.png). So the correct thing to do is always one of the above two options.

How does this tie in to your thoughts? Fraggle 00:16, 18 June 2007 (UTC)
 * Well, 16:10 is becoming increasingly common in desktop monitors, and almost all laptops are 16:10. I have a 4:3 desktop and a 16:10 laptop. That's not the main issue, anyway. My main point was what you said, that widescreen should "expand the rendered field of view", and that the image should not be stretched to fill the space.
 * I do think if widescreen is offered it should be programmed correctly. I see no point in including 4:3 and 16:10 designed to stretch into 4:3. That's redundant, and the stretched one won't look as good. Additionally, most modern computers will letterbox the widescreen and it won't stretch to fit correctly. Might as well include actual widescreen at the desired aspect. Sorry if I've been confusing, guess I'm not good at explaining things. Tangent 03:38, 18 June 2007 (UTC)
 * Yeah, the thing you have to realise though is that 320x200 isn't intended to be widescreen :-)
 * I think we can incorporate the widescreen stuff into the article, but it should be in a separate section at the end to avoid confusing the issue. Fraggle 08:19, 18 June 2007 (UTC)

Automap image
I'm a bit confused over what is supposed to show here. As far as I see it, it actually provides evidence that what this article says is not true, because when the 320*200 image is stretched to fill a 4:3 ratio display, it becomes warped in a way that is obviously not respective of how it should look.

Now looking at the automap article, it says A rectangular room in E1M3 is distorted in the automap, due to incorrect aspect ratio correction.  However, I just checked in vanilla Doom, and this is exactly how it shows the automap in its "320*200 stretched to a 4:3 ratio display" mode. So unless the author of this image is saying that vanilla Doom uses a wrong aspect ratio correction (which goes back to my previous point), I don't really understand what point this image is trying to get across. Nuxius 11:28, 19 May 2008 (UTC)


 * It's because although the graphics, such as the titlescreen and the hud face were designed to be stretched from 320*200 to 320*240, this aspect ratio issue was ignored when writing the automap code. It's quite easy to squish down an image that is essentially outside of the program. It's not quite as easy to mess with how vectors and lines are rendered internally. Making the game display non-streched one moment (as intended for the automap) and then making it streched the next (as intended in gameplay) would be a pain in the ass to sort out, and of course the automap wasn't as high of a priority as the other rendering operations.


 * Basically, yes. Since the sprites "look" right in 320x200 we can argue that they were designed for that resolution. But the automap doesn't look right - a square room doesn't actually appear square. However, I don't agree with the statement "It's not quite as easy to mess with how vectors and lines are rendered internally." Actually that is simply a matter of multiplying each vertical coordinate by a specific constant. I think the guys just didn't notice, or didn't care. Zack 13:59, 4 June 2008 (UTC)

Attitude polarization
This article seems to suffer from a horrible case of attitude polarization. Although it does a good job showing how id could have intended for Doom to be displayed stretched from 8:5/16:10 to 4:3, it just assumes that is true and leaves it at that, either blantly ignoring evidence to the contrary or not even bothering to attempt any further research.

Over the past few days (never knew this article even existed before a recent thread at Doomworld), I have started to gather evidence that supports the opposite of what this article states, and some other evidence that actually suggests id tried to compromise and make Doom look O.K. in either mode (stretched or original).

Please note that my research isn't set out to prove this article wrong; the evidence displayed here is good evidence supporting this theory. To be honest, I can't really see any way a person could make an argument against any of the points made. I'm merely providing evidence for alternatives that suggest this issue isn't so cut and dry as the article tries to make it out to be. Nuxius 11:55, 19 May 2008 (UTC)
 * There has always been a degree of controversy over this article; you can see it in this very talk page with Tangent's comments above, in fact.
 * It's worth pointing out, though, that there can be no controversy over the fact that 320x200 mode is displayed stretched to a 4:3 ratio. It is, put simply, a fact that the video cards that existed at the time Doom was created displayed 320x200 mode in the stretched format (non-square pixels). The controversy is whether Id took this into account when developing the game; the title screen graphics provide pretty compelling evidence for believing that is so. Please note that modern video cards do not always behave the same way.
 * However, I'd judge that the aspect ratio issue was not taken into account for at least some of the components of the game. The most obvious is the automap; the automap drawing code assumes that the screen has square pixels, so the map appears distorted as a result. As a programmer, I know that this is the kind of subtle detail that has to be taken into account while writing the entire engine in order to be done "properly"; it's quite likely that they simply didn't take it into account while writing the automap code, or didn't consider it important enough to spend their time fixing. Fraggle 23:18, 19 May 2008 (UTC)
 * After reading your post, it seems as though we are in more agreement than what this particular article would suggest. (particularly here However, I'd judge that the aspect ratio issue was not taken into account for at least some of the components of the game.)
 * After further thought, I think it would probably be better to change some wording a bit to make this article more "neutral", versus adding other views which would only complicate matters for the end reader. Nuxius 23:06, 3 June 2008 (UTC)

Resolutions Do Not Have an Aspect Ratio
The so called "320x200" does not have an aspect ratio of 4:3. It depends entirely on the monitor. If your monitor has square pixels then you got square pixels, if they are rectanglular then they are rectangular. LCD panels usually always have square pixels regardless of the aspect ratio of the monitor. All that "Oh well it's VGA mode and VGA mode only exists on hardware from 1993 and must always be 4:3" is nonsense, if a program cares about how big the screen is, it can always probe the monitor for the DPI or ask what it is (or steal it from the OS). But yes, Doom appears to have been designed to be ran at 320x200 with an aspect ratio of 4:3 (pixel wise). My laptop display has an aspect ratio option which when faced with lower resolutions, always makes the pixels square and not stretched out more horizontally or vertically. 320x200 is scaled perfectly 4 times so it fits the entire screen, but the pixels are still square, and it's still 16:10, and my VGA works fine. GhostlyDeath 15:51, January 26, 2010 (UTC)


 * True hardware mode 13h *does* have a fixed aspect ratio *on a CRT monitor*, and it is always 4:3. The problem arises under modern machines that do not actually support mode 13h - this support is becoming exceedingly rare, especially on newer ATi video cards, some of which will not even set into ANY screen mode lower than 640x480. The issue at hand in this article is that DOOM was designed for Mode 13h, which appeared 4:3 despite having a 16:10 framebuffer. I think that your issue is that LCD monitors cannot support tall pixels, because they have a fixed raster. CRT monitors were capable of adjusting the vertical retrace, which is exactly what happens when setting modes 320x200 or 640x400 - the audible clicking and other sounds given off by CRTs when they change into this video mode was a result of the beam guiding mechanisms physically moving to account for this difference. Quasar 23:53, January 26, 2010 (UTC)


 * However, for CRT monitors you almost always can change the stretching so that it makes the pixels square again (letterboxing it on the top and bottom). My old CRTs usually just try to fill the entire image on the screen so you don't need to adjust it at all. Is there any standard documentation for VGA capable CRT monitors that mode 13h must be displayed 4:3 on the screen? GhostlyDeath 01:47, January 27, 2010 (UTC)


 * "The problem arises under modern machines that do not actually support mode 13h - this support is becoming exceedingly rare, especially on newer ATi video cards, some of which will not even set into ANY screen mode lower than 640x480" To be honest I think it's fairly reasonable nowadays.  Any program that relies on the existence of that mode is inherently broken; it's crazy that manufacturers should have to keep on supporting this oddball mode forever (the non-square pixels thing is genuinely weird nowadays).
 * Even on cards where the mode does exist it's often undesirable to use it, because all modern monitors are flatpanels, and I haven't encountered a single flatpanel that didn't do a "resampling" (ie. blurry) scale-up of non-native resolutions. When running Chocolate Doom full screen, I run it at 640x480 or 800x600 because they look more "like 320x200" than the real 320x200 present on my card does.
 * Basically my attitude towards these kind of changes is the same as my attitude to Windows not supporting DOS apps any more: the manufacturer has removed support for it, and as far as I can tell, they have good reason to do so. If you don't like that, the best thing to do is either build a "retro PC" out of old parts that will do what you want, or use software that can reproduce the old behavior (DOSbox, Chocolate Doom, etc). Fraggle 12:44, January 27, 2010 (UTC)


 * But back to my previous question: is there proof of documentation that 320x200 (by mode 13h and friends) must have a 4:3 pixel ratio? DOSBox's configuration has an aspect option that makes 13h modes 4:3 (at least on my panels). CRT monitors are never always 4:3 (you can buy widescreen ones or different aspect ones) and you can also adjust the shape of the picture. 320x200 is meaningless unless you are saying 320x200 on a 4:3 monitor stretched vertically to fit. GhostlyDeath 02:21, January 28, 2010 (UTC)


 * I don't know enough to answer definitively, but you may be able to get an answer of "yes" by reading some old documentation on the VGA card and its registers. All I can say is (1) as far as I know, all graphics hardware at the time Doom was released displayed its 320x200 mode fullscreen on 4:3 monitors, and (2) there is compelling evidence that the Doom graphics were designed for this (see the article). Point 2 is the important part, really. Fraggle 14:15, January 28, 2010 (UTC)