Stolen Pixels #223: The Expensive Dimension

By Shamus Posted Tuesday Aug 31, 2010

Filed under: Column 44 comments

Yes, this comic actually went up a week ago, but since I was afflicted with blindness and making little-girl noises for a week I didn’t get around to linking it until now. Heads up: If you’ve got an old set of red / blue 3D glasses, you might want to hunt them down now. (Although the comic is perfectly intelligible without them and was made with the expectation that most people wouldn’t have them.)

And yes, I am aware of how silly it was to be making stereoscopic images when I was nearly blind in one eye.

I love anaglyph images. I remember in the 90’s I would take screenshots from adventure games like Space Quest and cut the image into its component pieces. Then I’d reconstruct the thing as an anaglyph. A couple of people asked about how these are made. So here is the short version, inasmuch as anything on this site could be counted as “short”:

The trick to these images – what makes them seem 3D – is that they trick your eyes into looking at two different images. It takes advantage of the fact that your brain assumes that when your eyes are looking roughly parallel you’re seeing something far away, and if your eyes have to cross a bit to look at the thing then it must be close.

So step one is to get two different images from slightly different points of view. Take a picture, then take a step to the right and snap another.


Now we want to trick our eyes so that each eye will look at a different image and assume they’re looking at the same thing. The easiest way is with a color filter. Red / green are usually used when dealing with images in print, and red / blue are usually used when dealing with television or theater.

Now, it’s possible to do this without obliterating the colors. For example, this one on Wikipedia is a pretty good color photograph:

But I’ve never been terribly successful at making color work. (I’ve never read a how-to guide on this stuff and everything I know is what I’ve discovered through experimentation.) When I try to make color images, often I’ll end up with a good deal of double-image problems where one eye can see both images and the effect is diminished or fails entirely. So the safest thing to do when making something like this comic (where visual grandeur and robust color use aren’t exactly high on the priority list) is to turn the images into greyscale.

Take the greyscale image intended for the right eye and tint it fully blue. If done right, the image should be clear when looking through the blue side and black when looking through the red side.


Then do the same for the other image, turning it red. Then blend the two images together in Gimp or Photoshop or whatever you got. (Additive blend. The effect is usually called “Screen”.) This produces the simplest and crudest anaglyph.


And even this is likely to fail in a lot of cases. If the two images are further apart than the viewer’s eyes, then the effect might not work. It’s pretty hard to prevent this when you can’t control how big their monitor is, how close they sit, or how much the viewer might zoom in on the image. Then there are all sorts of color problems. Not all monitors produce the exact same colors and not all glasses have the exact same colors (the shade of blue seems to vary quite a bit) and these discrepancies can lead to double-image problems.

The inspiration for the joke came from this:


I was casting about for joke ideas and I stumbled across that image and thought, “Fair enough. I can make 3D. Heck, I can make terrible 3D!”


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44 thoughts on “Stolen Pixels #223: The Expensive Dimension

  1. Michael says:

    Without wearing the glasses (which I’m sure I have around the house somewhere) looking at your home-made anaglyph makes me feel like I’m hallucinating.

    Everything is purple, and I’m seeing varying degrees of double.
    (Oh.. song time! Jimi Hendrix meets Foreigner!)

    You know, like in the one vault from Fallout 3 where they tested the airborne relaxants.

  2. Conlaen says:

    Tempted to get some glasses to see what the comic looked like in 3D. But the only other thing I’ve had in my house that ever needed 3D glasses was an episode of Chuck I think. So until there’s more out there that makes it a worthwhile investment, I’ll just stick with imagining it ;)

    1. Jabor says:

      If you don’t have 3D glasses, someone in the escapist comment thread posted a side-by-side of the images. You just need to go crosseyed to get them to overlap, and then you’ll see the 3D.

  3. Kdansky says:

    It was a great joke, especially because 3D is so completely pointless with only two guys sitting on a couch to begin with. I also very much liked the bigger format. I’m really baffled why most webcomes still assume our monitors cap at 640×480. See PhD, or Order of the Stick, which are pretty hard to read due to the ridiculously low resolution.

    1. Nick Bell says:

      I think a large part of why some comics seem comically small is historical. Order of the Stick was started in 2003; PhD was started way in 1997, 13 years ago. They continue to use the same format for internal consistency or simply out of habit. The sizes and resolutions were probably appropriate for the time they were created. They now simply show their age by not having changed.

      1. SKD says:

        They could also be sticking to a standard format for print reasons. If they offer print editions for collectors and fans then it is easier to keep everything in the format used for their books than reformatting everything when it comes time to send it off to the publisher.

      2. 8th_Pacifist says:

        That doesn’t explain why the text in Order of the Stick is so ungodly small, especially compared to how it used to be. I eventually stopped reading it because it became so hard to make out.

        1. Jake says:

          OoTS is ungodly small? I’ve never had any problems with it whatsoever.

        2. Athan says:

          If you think that’s bad try this:

          I always end up sitting way forward in my chair to read those.

          1. Somebody Else says:

            The reason for the small print on those is that it’s a newspaper strip, released online (and translated to English) as an afterthought.

        3. Felblood says:

          A lot of the readers for those comics are still using old aspect ratio monitors, with graphics cards that don’t support above-eye-resolution by large-number-of-pixels. It makes sense to include those people in their potential user base.

          Is it better to make you hit Control Plus, or make those guys scroll sideways, to read the right column of a page format comic?

          Backwards compatibility will not be vilified!

    2. Noumenon says:

      I’m showing my age by not having changed: I use 800×600 resolution, so I can actually see the details of things from the floor where I work.

  4. Zukhramm says:

    Aaaw, now I need to find those glasses even more, I know I have a pair somewhere. I was already looking because Minecraft has the option to run in 3D anaglyph mode.

  5. Jarenth says:

    I’d say that description was short for this site, yeah. You didn’t even use three thousand words for it (480, actually), and there’s barely enough material there for a five-month-spanning series on the physiology of the human eyeball.

    You showed some real restraint, there.

  6. UtopiaV1 says:

    I wore the correct glasses, i tried sitting a variety of distances from the monitor… didn’t work though :(

    Oh yeah, glad to hear you’re feeling better Shamus!

  7. Mari says:

    I’m stereoblind. Remember those “Magic Eye” things from when we were kids that everybody was crazy about? Yeah, I can’t see them. I thought for years and years and years that I was just a complete loser for not being able to see them when every one else could but I mentioned it once to a doctor friend and he explained about stereoblindness. Anyone with amblyopia (which I have) is stereoblind. So most forms of 3D are lost on me since my brain only uses the input from one eye. It also makes backing down my incredibly long, narrow driveway a real pain in the rear (the same condition makes it very difficult to judge distances because “real” 3D vision is hampered, too).

    1. Matt K says:

      I on the other hand am not stereoblind but cannot ever see those Magic Eyes. I guess I’m just a complete loser then :)

      Oh and thanks Shamus for those horrible images my eyes are like freaking out right now.

      I do enjoy your exdplanation though, interesting stuff.

      1. Will says:

        The Magic Eye stuff requires a certain trick that some people learn, and some people don’t.

        The trick is to basically look through the picture, focusing on a point a couple of feet behind it, you then move that point back and forth and the image in the magic eye should appear.

        You can sometimes trick your eyes into doing this by holding the image really close, or focusing on something in the distance and then moving the image into your field of view, and once you know how to do it you can learn how to do it at-will with a bit of practice. But i have noticed that quite a lot of people just never realize what it is they’re supposed to be doing. I learned the trick by accident when i was in my late teens and i noticed that with a bit of effort i could focus behind my textbook and make all the math problems go blurry XD

        It’s also fun to focus on a point about 2 feet behind someone’s head when you’re talking to them, apparantly it is very disconcerting.

        1. Deoxy says:

          Get a “Magic Eye” picture framed, make sure the glass is VERY clean, look at your own reflection in the glass, and slowly move closer or farther until you find the right spot.

          That’s the easiest way to “get it” the first time – a reflective surface makes you focus “behind” the surface.

          Wouldn’t help someone who is stereoblind, though.

          Edit: I LOVED those Magic Eye things – they are so awesome and fun. anaglyphs… eh, they can be nice, I guess. I even saw Avatar in 3d at a very nice theater with my wife, and the difference was noticeable, but nothing too amazing. And the whole point of that movie was special effects eye-candy (plot = FAIL).

        2. Michael says:

          The other thing he could do is just go cross-eyed.

          Most Magic Eye images (Wikipedia tells me they’re called stereograms) are made to be used with the “thousand yard stare” method, so this’ll invert the image; instead of a bump on a flat surface, you see an indent (on a flat surface).

          Admittedly, for most people, the cross-eye thing is harder to do. You have to line the pictures up in your vision while they’re out of focus, but it makes for more interesting images!

          1. LassLisa says:

            Wait, they’re supposed to pop OUT? … and yes, I’ve always used the cross-eyed method.

      2. Mari says:

        Or maybe you’re just honest. I’ve sometimes suspected that about half the people I know who claimed to see the image in Magic Eye prints were lying. I never knew anyone back then who admitted to not being able to see it, but I hear that from a lot of people now.

        1. Jarenth says:

          I had to take a course on Human Perception once, which included a section on stereoscopic vision and a few of these magic eye pictures; even with a university-level textbook and several tens of pages of explanation and guiding, it took me the better part of a month to figure out how to see the pictures. And even then, not all of them.

          So what I’m saying is, you could very well be right.

        2. Felblood says:

          When I was a kid, I thought I could see the things, and didn’t know what the big deal was.

          It wasn’t until high school what I actually got one to work, and realized why I’d been so unimpressed before.

  8. Ross Bearman says:

    I’d just like to chalk one up for preferring the new layout. Firstly, more comic, yay! Secondly, I always forget to read the sidebar text as I always decide to read it after the comic, and whilst laughing heartily at the comic, I forget there is more at the to. I also always read the blog post after the comic, so usually I just quit away to come and read this.

    1. Zombie Pete says:

      Count me in, too, as a fan of the new format. For some reason with the old format I had this burning desire to read the text first, so I’d have to scroll down and try not to look at the comic. This way, I forget about the text and get an added bonus when I’m done with the comic. And yeah, bigger comic is better. More room for more details, should you need them.

      Welcome back to the land of the seeing.

    2. Jep jep says:

      I have to agree. I usually read the text afterwards as well, but it’s sometimes easy to miss when reading a series of comics (like Left 4 Dumb) and my focus is on the comic, clicking on “Next” comes sort of a reflex. I’ve often had to come back to the page when I realized that I missed the side text yet again. As it is now, it’s easier to spot and I’d imagine it should gain the attention of anyone who bothered to read the whole comic.

    3. Namaps says:

      I like this format too. It’s makes the text seem like a more natural follow-up to the comic.

  9. Peter H. Coffin says:

    For anyone playing with this, a VERY handy program for fussing between stereo formats, see Stereo Photo Maker at . It handles both independent left&right images, joining them simply and easily into anaglyphs, pairs for both parallel (like the pair in the article) and cross-eyed free-viewing, and MPO (Multi-picture Object) files as generated by the Fujifilm stereo digital cameras.

  10. Peter H. Coffin says:

    Now that I’ve looked at it, there’s a few vertical registration issues (where the paired parts of the image differ vertically as well as horizontally, which makes visual fusion fail or be difficult) especially in the left edge of panel 1, some rivalry in panel 2 which is looking like it’s cause by “toe-out” between the “camera angles” for the left and right, making the background separate more than it should. Ideally, you’ll want exactly perpendicular separation of about 20:1 to as little as 50:1 of your perceived distance to your subject. That is, if your “camera” is 3500 render-meters from the closest subject, you’ll want to move your second shot of the pair about 100 render-meters to the perceived “right” of where the first shot was from. Using lower than 20:1 (more width) tends to make things seem smaller than “real” (hyperstereo) and closer, and a higher than 50:1 (hypostereo) makes things appear larger and further away. Toeing in or out (pointing the cameras closer or further apart “horizontally” to the separation/inter-ocular distance can sort of mimic this effect in the same way that a zoom lens can kind of mimic moving closer to a subject, but with the same kind of distortion.

    Yeah, this is kind of a hobby. I’ve owned 3D cameras for 15 years and currently own and use four of them….

  11. Soylent Dave says:

    I can’t wait for this resurgence of faux-3D to die out. Again.

    Maybe it’s just because it makes me feel old (having seen the exact same technology pop up every 10 years, heralding itself as the ‘future’ of entertainment), but I think it’s just because it’s rubbish.

    If it was actual 3D, like we were promised by science fiction, I might be more excited. I might also be more excited if I didn’t already wear glasses, so I didn’t to stick additional pairs of badly designed spectacles over the top of my existing pair.

    Bah, humbug, whinge, moan, etcetera.

    (I could go on at length about this, but I already did a couple of posts back on my own blog, and it didn’t make me feel any better…)

    … I did like anaglyph glasses when I was little, mind. I think that was probably before I needed specs of my own.

    1. pulse says:

      There are filters that can be attached to normal glasses. One of my co-workers at my old workplace had them and was apparently happy with them. (We had a rather expensive monitor at work that seemed to use the same technology as in the cinema, purchased for geographic data acquisition from aerial photographs.) I unfortunately don’t know the details about price, retailers, what models of glasses they fit on, etc.

      Of course this still leaves the fundamental problem that stereoscopy with multiple viewers can never (as far as I know) be real 3D.

  12. SteveDJ says:

    I just wanted to comment and say “Please don’t go back to the other format”. Not just because I, too, liked the text at the bottom. But I LOVED the big/oversized images for the comic. Even when back to 2D, it would be wonderful to have such large frames in your strip.

    It feels like High-Def compared to before, and everything is going HD now… :)

  13. Aldowyn says:

    Yet another reminder that 3D is old hat, and is likely a fad- especially in movies. It may become standard, but the same way as HD is standard– it’s not a gimmick, it just makes it look better and more realistic.

  14. ehlijen says:

    Just out of curiosity if anyone happens to know. Why are eletronic media red/blue and print media red/green?

    My guss is it’s printing related?

    1. whitehelm says:

      I assume it’s because electronic media produces light, so it uses the additive color wheel (red/yellow/green/cyan/blue/magenta) in which red and cyan are opposites. Print media absorbs/reflects light, so it uses the subtractive wheel (red/orange/yellow/green/blue/violet) in which red and green are opposites.

      1. Will says:

        You are correct sir.

  15. LintMan says:

    I had a friend make 3D photos to send out with his wedding invitations (along with a pair of red/blue glasses). His “3D camera” was a pair of cheap disposable film cameras taped together side by side. I think he might have covered lenses with the same red/blue filter he made the glasses from.

    Then he scanned the photos, blended in photoshop and printed them back out. They came out pretty decent for him just winging it.

    His wedding song was “Linus and Lucy”, and they had a parade of giant (6′) street puppets afterwards, so the 3D thing was par for the course for him. :-)

  16. D says:

    Irrelevant to 3D: I prefer this format for the comic above, text below. Feels less like the text is sandwiched between loud bright comic and loud bright ads. Just saying.

  17. Nick says:

    They have 3D TVs now that don’t require the glasses, although you have to sit at certain angles to the screen to see it.

    1. Will says:

      Current ‘3D’ is an optical illusion rather than ‘true’ 3D, as with all optical illusions, it only works if your eyes are in the right spot.

  18. HeadHunter says:

    Here’s hoping that this 3D resurgence is another fad. Since an eye injury of 25 years ago, I have no depth perception and little peripheral vision on the right side. This has caused my right eye to drift inward, and even surgery has not fully corrected it. There’s a permanent double vision which I’ve mostly learned to ignore as a result.

    Needless to say, any 3D that requires glasses or a similar effect is lost on me – I simply can’t look at it and can never hope to see it properly.

    Disney/Pixar are doing some new 3D effect for some of their movies that doesn’t require glasses – those sorts seem to work OK for me. That is to say, they look much like the “real” world does to me, which I’m assuming is a bit different than it appears to those with stereo vision.

  19. pulse says:

    My 3D glasses and most of my other things are in cardboard boxes at the moment because I’m preparing to move, but it looks like the image from wikipedia has simply kept the red channel of one image and both blue and green from the other. It is probably a good idea to partly desaturate the original images before separating the channels to make sure that all features show in both images. I’ll have to experiment with this a bit when I’m done moving.

    I’ve gotten the impression that the red/blue glasses are an improved version over the red/green ones. The red/green ones look like they are truly just red and green, with both filters removing blue light. If this is right, it means that full colour images are impossible with those glasses.

    The red/blue glasses seem to allow only red light through the red filter, but both blue and green through the “blue” filter, which is why it looks so bright. This also seems to fit with the wikipedia image.

    I think the modern 3D technology uses polarized light for the filtering, allowing both eyes to see the whole spectrum of colours.

    — edited in later —
    Oh and I like the layout of this comic :-)

    1. Lemeza says:

      You’re right – the most common 3D glasses are Red-Cyan not Red-Blue (cyan is green plus blue light for those who don’t know).

      I also prefer the new layout because I’m terribly indecisive – ‘Should I read the text or the comic first?’.

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