Find the Odd Disk

(colors2.alessandroroussel.com)

71 points | by layer8 5 hours ago

37 comments

  • zootboy 5 hours ago
    I wish this had a "I can't tell" option. A few of the really hard ones I got right, but I'd say it was more of a lucky guess than a genuine ability to discriminate the difference.
    • Freak_NL 5 hours ago
      Quite. With the odds being 1 to 3 you'll pick the right one when you have to click one at random to proceed, the results get skewed.
      • Retr0id 4 hours ago
        If you repeat the test a few times, it'll average out.
        • lucb1e 3 hours ago
          That's why there's 20 rounds I guess. If you could just press "all the same" it wouldn't have to be as many
  • lucb1e 3 hours ago
    I was wondering if it got harder or if it's just random:

        function generateColors(difficulty, blacklist) {
            ...
            let sample = Math.floor(Math.min(Math.max(0, 1-Math.pow(1-difficulty, 1.5)), .99)*5);
            let distance = (5 - sample)/5;
            ...
        }
        function setupRound(blacklist) {
            ...
            const data = generateColors(currentRound/totalRounds, blacklist);
            ...
        }
    
    Plotting that first magic: https://lucb1e.com/randomprojects/js/testformula.htm#%24%28%...

        round#  difference
         0-- 2  5
         3-- 5  4
         6-- 9  3
        10--13  2
        14--20  1
    
    The "blacklist" parameter prevents that you get the same challenge twice. Note also that it submits every answer to the server (fine imo, but I think it would be even nicer if this was mentioned on the page)
  • layer8 5 hours ago
    This is from the creator of the ScienceClic YouTube channel [0]:

    “As part of the next video, which will be out in a few weeks, l'd like to invite you to take part in an experiment about color perception. If you don't experience color blindness, l'd greatly appreciate it if you could take this test. Feel free to try it as many times as you like, think about it as a game!”

    [0] https://youtube.com/@scienceclicen

  • susam 45 minutes ago
    19/20 - <https://i.imgur.com/GplfQbO.png>

    By the way, I keep Night Shift enabled all the time: <https://i.imgur.com/LGkSlJZ.png>. I don't know how much it matters in a game like this.

    See also <https://susam.net/myrgb.html> for a colour guessing game I wrote last year.

  • wrs 29 minutes ago
    Toward the end, I think the confounding effect of the afterimages of the discs was bigger than the difference between the discs. (That is, when looking at the three discs in turn, the effect of the afterimage of disc 1 on judging disc 2, etc.)
  • tripdout 5 hours ago
    17 out of 20. Was super easy until #10 and I had to stop and think more carefully (which was actually my first mistake), and then I got #14 and #15 wrong. The score was about what I expected, though - would've been surprised if it was <15 correct.

    I wonder how much of this would come down to screen calibration / color accuracy? If everything's consistently off in 1 direction I guess not much, but I would imagine certain shades might appear effectively the same on some cheaper screens?

  • nkrisc 5 hours ago
    Would be interesting to get some basic analysis of my results. From a glance it appeared that the ones I missed (6) tended towards red. The low saturation ones and green ones I found to be easiest, but was there any actual significance of the distribution of my errors? Simply too small a set to say?
    • hilbert42 4 hours ago
      I got the same number wrong but I've passed every Ishihara test ever thrown at me. I did this test on a cheap mobile that's not calibrated, so it's anyone guess what its gamma and transfer curves are like.

      One should only take such tests seriously if one's using a properly calibrated monitor and it's viewed under ideal viewing conditions.

    • robertclaus 53 minutes ago
      Interesting! All of my misses were blue leaning a bit towards violet.
  • ryao 30 minutes ago
    This seems to be a test of the color accuracy of a display. I got 17/20 and the 3 I got wrong were the last 3. I did this on my iPad Pro. For the last ones, they all looked the same to me.
  • fallinghawks 4 hours ago
    19/20. The first many were very obvious. I missed #14 and I think right around there I started to slow down because the differences were getting smaller. Looking away and then coming back helped, I think. It seemed like if you look at them too long, whichever circle you're looking at seems to shift color and it becomes really hard to discern the difference.
  • blueflow 5 hours ago
    How much of the result is vision accuracy and how much is dependant of the display?
    • hilbert42 4 hours ago
      As I've mentioned, you can't take this seriously unless you've a properly calibrated monitor.
      • wtallis 38 minutes ago
        Calibrating a monitor is intended to ensure that colors on your monitor closely match colors on an ideal reference monitor. That's not the same thing as ensuring that two different colors on the same monitor actually show up differently; that's a much looser quality standard, because even a badly mis-calibrated monitor may still show both colors as distinct wrong colors.

        I would only expect poor calibration to break this test for colors near the edge of the display's gamut, or if there's a drastic-enough shift that the color space's lack of perceptual uniformity means a numerical difference that should have been visible ends up in a different part of the color space where that same numerical difference is not perceptible.

  • havan_agrawal 3 hours ago
    Shouldn't there also be a few "control" challenges sprinkled in where all three are the same color and there's no "right" answer? If the test is implemented well and/or there is no human bias (either from the previous question or from the positioning of the circles), then you'd expect to see a uniform distribution of answers on the control. If there is bias (e.g. some innate preference for the top circle (say)), that should get adjusted for in the final analysis.
  • terr-dav 37 minutes ago
    20/20 (once) - I found that by looking at the edge between the border and color sample that I could usually tell pretty quickly.
  • Retr0id 4 hours ago
    Interesting. I only got 15/20, and previously considered myself "above average" at colour distinction tests but based on other replies that's not an especially good score. I'll try again, going more carefully.
    • thechao 6 minutes ago
      I have poor color discrimination, but excellent flicker detection (?). This last skill was discovered by the senior devs when I was doing GPU driver debug, and “we” were looking for an extremely transient high-refresh rate tile clear issue. The issue only occurred at 120Hz (or higher) refresh rate with solid clear color on a large screen, with nearly identical colors. About one 4x8 pixel tile every minute or so. That was a boring few days, let me tell you.
    • Retr0id 4 hours ago
      Ah, yes, 19/20 the second time (only the last one wrong).

      The first time I kept my eyes fixed in the same place roughly in the middle which clearly wasn't a good idea. On the second attempt I glanced between each circle in turn, trying to discern the difference over two points in time rather than two points in space.

  • Animux 4 hours ago
    Was way easier after deactivating the Android night light.
  • yellowapple 4 hours ago
    13 out of 20 for me. Would've been 14 but I misclicked on one early on.
  • smusamashah 2 hours ago
    14/20. Increased brightness to full, turned off blue light filter (aka night light on Android), zoomed in, scrolled the circles up and down to dissipate after image from eyes, 19/20.
  • MisterTea 4 hours ago
    7/20. I'm also red green colorblind so that likely has something to do with it. Could also be the phone screen I'm looking at.
    • MisterTea 3 hours ago
      With phone screen on full brightness I was able to get 14/20.
  • morning-coffee 3 hours ago
    Not sure what to make of this. Most looked the same and I couldn't tell if I was really seeing a difference or not. 12/20. (And I am color blind, so not sure if that has a lot to do with it or not.)
  • nuancebydefault 5 hours ago
    What stood out a lot in this exercise is that when looking at, versus near a disc, its luminance (or maybe the color as well) is perceived as changing. Almost the same i have when staring at not too bright stars, they seem to disappear when staring directly on them.

    And related, I once had an 'eye migrane'. During that half an hour, the figures of a clock disappeared the moment i looked at them.

    • fallinghawks 4 hours ago
      I'm curious how the eye migraine is related. I had one many, many years ago. It was a smallish (palm at arm's length) oval in the center of my vision that looked like snow on an analog TV, accompanied by a feeling of overwhelmed by all the colors of the products on the shelves (I was in a grocery). It stuck around for about half an hour for me as well.

      I've also had eye floaters which cause things to distort and can be hard to see through. For about 6 months I had a large one in the center of my left eye vision, which was a bit scary when I discovered I might not see a car reflected in my wing mirror.

      • twodave 1 hour ago
        I’ve had visual migraines ever since I started training hard with weights. Played sports in High School and never had one, but suddenly I’m doing CrossFit in my late 30s and an hour after a workout I get these sparkly jagged lines in my vision (both eyes!). It took a while to even be able to describe them, let alone figure out what they were. Thankfully there’s no pain and they clear up after a while, but I have noticed since this all started that I’m also a bit more sensitive to screen brightness. That HDR emoji article from the other day was kind of triggering.
    • RetroTechie 4 hours ago
      Similar experience. What surprised me: sometimes the odd-one-out was really quick/easy to see, and other times it took much longer & I thought "at the end, they'll say all disks were the same color".

      Got 14/20

  • amelius 4 hours ago
    I think it matters what colors you looked at in the previous screen. It takes a while for the eyes to adjust.
  • _Algernon_ 4 hours ago
    17/20

    Wonder how big an influence the type and quality of screen has. Do OLEDS give an advantage for instance?

  • rkagerer 4 hours ago
    My 14/20 went up to 18/20 after I turned up my phone brightness.
  • ilker2495 4 hours ago
    17 out of 20. good enough for me. actually, i wonder how many of the 17 were just lucky guesses haha! they mention data in the end screen, i wonder if it will be made public (so i can see where in the bell curve i sit)
  • fmajid 2 hours ago
    I got 17/20, but then again I have a high-end NEC PA302W hardware color-calibrated monitor.
    • Cthulhu_ 1 hour ago
      18/20 on an uncalibrated "gamer" spec display with windows' late night colour yellowing turned on. I'd argue spec/calibration isn't maybe that important, as long as a difference can be spotted.
    • tkcranny 2 hours ago
      18/20 on an iPhone – they’ve have Display P3 wide colour for many years.
  • isoprophlex 5 hours ago
    18/20 correct, I think I did well? Interesting how sometimes it's more of a feeling than an objective perception.

    At the end it says I can play again, because it'll generate more data. But for what?

    It'd be cool to see some stats, or learn a bit more about what I just did...

  • lucb1e 3 hours ago
    How do I know my screen can display all of these correctly? I tried on three different screens, one of which I know is bad, and got 16, 16, 18. Is those two mistakes the error margin of the screen if my eyes are fine, or much more likely to be the error margin of my eyes?

    For those reporting scores: please also report device type, like LCD/OLED, or which phone model if applicable. Tweakers.net has a large database of screen color measurements. As mentioned in e.g. https://news.ycombinator.com/item?id=43746400, it can make quite a difference

    My 18 score was on an Oppo Reno8, the 16 score on the not-known-bad screen is some ~2008 display. On the former, Tweakers reports an average color error of 3.42 ΔE2000, 9.58 ΔEITP, or 2.60 ΔE2000 if white is excluded

  • OisinMoran 5 hours ago
    I think this would be more fun if it started out easier, but most importantly if it gave you some real world stats at the end, such as how you compare to others, or whether you're colorblind etc.
    • Freak_NL 4 hours ago
      I found it did start out really easy, getting harder half way. You might have some form of colour blindness (or a really bad monitor).
  • vinnymac 4 hours ago
    19/20 the neon blue one really messed with my head and kind of hurt to look at for some reason, so I am not surprised I got it wrong.
  • colordrops 48 minutes ago
    20/20 but I've always done well on these color tests. I had to pause for a second and look with my head twisted though so the afterimage of the previous color didn't affect the next one.
  • jjmarr 4 hours ago
    19/20 somehow on my first try. Near the end was just tiny differences in saturation or brightness.
  • theoa 3 hours ago
    Browser > right click on the dot > inspect the RGB numbers
    • Mogzol 3 hours ago
      The first line on the page says

      > Click the disk that's a different color. Use your eyes only!

      Inspecting the color is cheating.

    • fuzztester 3 hours ago
      Clever.
  • two_handfuls 4 hours ago
    Black text on dark grey background, sorry, that's too hard to read.
    • wtallis 27 minutes ago
      Your display might have a more serious gamma problem, because the contrast ratio there isn't horrible on the displays I've tried. Or maybe your display is just set too dim for your viewing conditions. The test probably does legitimately need the neutral grey background.
  • dark-star 1 hour ago
    I got 16/20 but I am colorblind and tried it on a small 8+ year old laptop screen in dubious lighting conditions :)
  • dvh 4 hours ago
    Your score: 20 out of 20. Mistakes: 0
  • fuzztester 3 hours ago
    Tried it briefly, upto 6. Got all right. Gonna do more later.

    Need some interesting optical illusion type of posts on HN!

  • nsibr 1 hour ago
    [dead]