[HN Gopher] Find the Odd Disk
       ___________________________________________________________________
        
       Find the Odd Disk
        
       Author : layer8
       Score  : 183 points
       Date   : 2025-04-20 19:17 UTC (1 days ago)
        
 (HTM) web link (colors2.alessandroroussel.com)
 (TXT) w3m dump (colors2.alessandroroussel.com)
        
       | OisinMoran wrote:
       | 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 wrote:
         | 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).
        
       | zootboy wrote:
       | 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 wrote:
         | 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 wrote:
           | If you repeat the test a few times, it'll average out.
        
             | lucb1e wrote:
             | 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
        
       | isoprophlex wrote:
       | 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...
        
       | tripdout wrote:
       | 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?
        
       | layer8 wrote:
       | 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
        
       | nkrisc wrote:
       | 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 wrote:
         | 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 wrote:
         | Interesting! All of my misses were blue leaning a bit towards
         | violet.
        
           | kamma4434 wrote:
           | Same here. The blues/purples were all alike. Reds and greens
           | were easier.
        
       | blueflow wrote:
       | How much of the result is vision accuracy and how much is
       | dependant of the display?
        
         | hilbert42 wrote:
         | As I've mentioned, you can't take this seriously unless you've
         | a properly calibrated monitor.
        
           | wtallis wrote:
           | 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.
        
             | hilbert42 wrote:
             | Well, I initially ran the test on my cheap vivo phone when
             | I switched to my Motorola the difference was very
             | noticeable, there's obvious color crushing/reduced visible
             | color gamut on the vivo, they're like chalk and cheese when
             | compared side by side.
             | 
             | BTW, I used to calibrate color grading equipment for the
             | film processing industry and the controls were strict, 18%
             | gray walls, D65 calibration sources, densitometric
             | equipment, Ishihara tests for me, etc. so I'm well aware of
             | the issues.
        
           | zamalek wrote:
           | I think you mean gamut? Calibration would only make the discs
           | have the _most_ correct color, not discernible colors.
        
         | schobi wrote:
         | There is certainly also a device limitation. I would expect
         | that with less than full 24 bits of color, some fields might
         | just look the same and the results do not depend on your vision
         | any more.
         | 
         | Let's say the device has a "24 bit color display". What about
         | eye protection color shifting? This limits the color space used
         | could reduce the effective remaining bit depth. Or maybe they
         | do temporal dithering to get more bit depth? Or maybe the 24
         | bits are already achieved with temporal dithering?
         | 
         | It does not need to be a calibrated display, but a cheap tablet
         | in sunlight will be worse than a color grading monitor in a
         | reference environment.
         | 
         | I hope they also register the devices used and analyze the
         | statistics on that.
        
       | nuancebydefault wrote:
       | 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 wrote:
         | 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 wrote:
           | 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.
        
             | z0r wrote:
             | Sounds like symptoms of impending retinal detachment - ex
             | discussion https://www.reddit.com/r/myopia/comments/o7rhi3/
             | retinal_deta...
        
               | robbiep wrote:
               | The characteristic 'jagged lines' of aura is not at all
               | related to the characteristic visual flashes of retinal
               | detachment which an entirely different pathophysiology.
               | Given that the advent of the flashes are new and related
               | to exertion however it wouldn't be unreasonable for the
               | OP to keep a log of onset and duration and consider
               | neurologist referral if they were to become more common
               | with consideration for screening imaging as there are
               | certain conditions related to exertion that can trigger
               | aura
        
               | twodave wrote:
               | I doubt it. I've described the issue to multiple eye
               | doctors, none of whom mentioned this. It's literally a
               | psychedelic looking jagged line in my vision (which I can
               | see with either of my eyes closed, superimposed over my
               | vision). I'd think if it were an eye issue directly it
               | only affect one or the other (or if both, it would be
               | discernible which one is flaring up).
               | 
               | During an episode I usually first notice it as it is
               | entering my focal region and interfering with reading.
               | Then it sort of moves across my field of vision until
               | it's in my peripheral, and then goes away altogether.
        
             | gblargg wrote:
             | I had visual migraines for years, and was thankful they
             | weren't full-blown... until I started getting headaches
             | that lasted 18+ hours (pretty sure they're migraines). Now
             | I'm just thankful I don't have multi-day-long ones.
        
           | alternatex wrote:
           | The symptoms you mention read like scintillating scotoma:
           | https://en.m.wikipedia.org/wiki/Scintillating_scotoma
           | 
           | I've had it happen many times and it's usually followed by a
           | regular headache. Quite terrifying the first few times it
           | happened to me. Felt like I was losing my sight.
           | 
           | Spending the whole night gaming when I was younger would
           | sometimes trigger it in the morning. Thanks to not having any
           | more time for that, it hasn't happened in years.
        
         | RetroTechie wrote:
         | 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
        
           | mrguyorama wrote:
           | For some of the easier ones, I was surprised by how
           | aggressively my brain was making what seemed like "close"
           | colors stand out. Like it was mentally "highlighting" the odd
           | one out. I thought that was cool, but eventually the later
           | ones were hard enough that the effect went away, and I was
           | much less confident in my choices, and I got 3 mistakes, all
           | in the last five rounds.
           | 
           | The way your brain manipulates your vision 24/7, with no way
           | to get around that, is truly crazy to me. There's all sorts
           | of effects in your visual system like edge detection and
           | certain types of stimulus suppression that it's crazy we even
           | feel like reality is coherent.
        
         | Liftyee wrote:
         | I experienced this too. IIRC the brightness-sensitive rod cells
         | are more concentrated in your peripheral vision while your
         | central vision has more colour-sensitive cone cells. This makes
         | the centre of your vision less sensitive to dim objects, so you
         | can see them only while looking indirectly (and they
         | "disappear" when staring at them)
         | 
         | Another related effect is flickering of badly designed lighting
         | only in my peripheral vision. When looking directly at the
         | lights they look fine, but when the lights are in my peripheral
         | vision they appear to flash distractingly. I think the
         | peripheral vision is optimised to detect fast
         | changes/movements. At least, that makes sense based on
         | evolution.
        
           | moebrowne wrote:
           | This is referred to as 'Averted Vision'
           | 
           | https://en.m.wikipedia.org/wiki/Averted_vision
        
       | fallinghawks wrote:
       | 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.
        
         | archmaster wrote:
         | Interesting. Got 19/20 too, and also missed #14!
        
       | Animux wrote:
       | Was way easier after deactivating the Android night light.
        
       | Retr0id wrote:
       | 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.
        
         | Retr0id wrote:
         | 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.
        
         | thechao wrote:
         | 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.
        
       | dvh wrote:
       | Your score: 20 out of 20. Mistakes: 0
        
       | two_handfuls wrote:
       | Black text on dark grey background, sorry, that's too hard to
       | read.
        
         | wtallis wrote:
         | 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.
        
         | layer8 wrote:
         | It's true that white text would be more readable on that
         | background: https://www.achecks.org/apca-accessible-colour-
         | contrast-chec...
         | 
         | The dark-mode browser extension I use changes the text from
         | black to white on that page, which I hadn't noticed wasn't the
         | original text color until you pointed out the poor readability
         | of the black text.
        
       | MisterTea wrote:
       | 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 wrote:
         | With phone screen on full brightness I was able to get 14/20.
        
       | ilker2495 wrote:
       | 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)
        
       | jjmarr wrote:
       | 19/20 somehow on my first try. Near the end was just tiny
       | differences in saturation or brightness.
        
       | _Algernon_ wrote:
       | 17/20
       | 
       | Wonder how big an influence the type and quality of screen has.
       | Do OLEDS give an advantage for instance?
        
       | vinnymac wrote:
       | 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.
        
       | rkagerer wrote:
       | My 14/20 went up to 18/20 after I turned up my phone brightness.
        
       | amelius wrote:
       | I think it matters what colors you looked at in the previous
       | screen. It takes a while for the eyes to adjust.
        
       | yellowapple wrote:
       | 13 out of 20 for me. Would've been 14 but I misclicked on one
       | early on.
        
       | lucb1e wrote:
       | 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 DE2000, 9.58 DEITP, or 2.60 DE2000
       | if white is excluded
        
       | theoa wrote:
       | Browser > right click on the dot > inspect the RGB numbers
        
         | fuzztester wrote:
         | Clever.
        
         | Mogzol wrote:
         | 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 wrote:
       | Tried it briefly, upto 6. Got all right. Gonna do more later.
       | 
       | Need some interesting optical illusion type of posts on HN!
        
         | fuzztester wrote:
         | Escher's creations are cool. Our chemistry teacher introduced
         | us to them in school.
         | 
         | https://en.m.wikipedia.org/wiki/M._C._Escher
        
       | lucb1e wrote:
       | 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)
        
         | tennysont wrote:
         | I appreciate
         | https://lucb1e.com/randomprojects/js/testformula.html, it's a
         | cool idea!
        
           | lucb1e wrote:
           | Happy to hear, though note the file is without l (lowercase
           | L) in the end (I guess autocorrupt is to blame here?). Fun
           | fact: if you remove the filename, it'll show you all the crap
           | in that directory, listing this file as being last modified
           | in 2015-09-27. If past performance is an indicator, it should
           | be stable to use for the next ten years as well :D
        
         | readingnews wrote:
         | Thanks for posting, I thought the same thing... my (useless
         | data point of one) results showed 100% accuracy except the last
         | four, which I thought "wow, I am just guessing now, can
         | literally not see a difference".
        
       | morning-coffee wrote:
       | 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.)
        
       | havan_agrawal wrote:
       | 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.
        
       | smusamashah wrote:
       | 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.
        
       | fmajid wrote:
       | I got 17/20, but then again I have a high-end NEC PA302W hardware
       | color-calibrated monitor.
        
         | tkcranny wrote:
         | 18/20 on an iPhone - they've have Display P3 wide colour for
         | many years.
        
         | Cthulhu_ wrote:
         | 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.
        
       | dark-star wrote:
       | I got 16/20 but I am colorblind and tried it on a small 8+ year
       | old laptop screen in dubious lighting conditions :)
        
       | colordrops wrote:
       | 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.
        
       | susam wrote:
       | 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.
        
         | richrichardsson wrote:
         | > I don't know how much it matters in a game like this.
         | 
         | Probably significantly since it explicitly tells you to disable
         | any blue light filters on your screen.
         | 
         | I think the website needs to be more explicit that this is
         | trying to gather data and that deviating from the test
         | parameters will skew the results.
        
       | terr-dav wrote:
       | 20/20 (once) - I found that by looking at the edge between the
       | border and color sample that I could usually tell pretty quickly.
        
       | ryao wrote:
       | 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.
        
         | gblargg wrote:
         | I wondered whether any display issues caused some to have no
         | difference. I wonder whether it could somehow do a test to be
         | sure your display is up to the task. It's annoying not knowing
         | whether it's a visual limitation or hardware issue that causes
         | wrong ones.
        
           | ryao wrote:
           | I just tried this on my desktop's monitor, which unlike my
           | iPad Pro that was factory calibrated, has never been
           | calibrated as far as I know. By round 11, the colors were
           | nearly imperceptible, although I managed to answer 4 more
           | correctly for a total of 14/20. Those additional 4 were
           | likely more the result of luck than actual perception.
        
       | wrs wrote:
       | 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.)
        
         | aimor wrote:
         | I noticed this too. I did much better covering up two of the
         | disks and looking at them one at a time, or comparing pairs of
         | disks.
        
         | gblargg wrote:
         | It could rearrange the discs each time to avoid this issue,
         | perhaps just flipping the pattern vertically each time.
        
       | 1970-01-01 wrote:
       | Not bad, I only missed 2 on purple and 2 on brown. It seems those
       | laser safety and solar eclipse goggles do indeed work!
        
       | the__alchemist wrote:
       | Aww. 16/20. Seems like this is the worst score anyone's posted,
       | other than the color-blind guy who tied me.
        
       | Liftyee wrote:
       | Is it sleep deprivation or do the disks actively change colour
       | and swap places?
       | 
       | I think this must be a low light optical illusion - something to
       | do with different sensitivity in center of eyes vs peripheral.
       | Will try again in the daytime.
        
         | daemonologist wrote:
         | I definitely noticed that effect (it's late here as well) - I
         | found it necessary for the last couple to look at the center of
         | the triangle rather than each dot in turn.
        
       | SoftTalker wrote:
       | 11 of 20.
        
       | saagarjha wrote:
       | Oh god this is colorblindness torture
        
       | akww wrote:
       | does 20/20 on my first try mean i get the job?
        
       | coolcoder613 wrote:
       | 19/20. I'm on a MacBook, so I have a pretty good screen.
        
       | noduerme wrote:
       | Got 18/20. I chalk that up to spending years as a graphic
       | designer. I'd like to see a similar study about which text was
       | perfectly kerned, or by how many pixels an element was off-center
       | or misaligned. I can spot that on billboards a block away, and my
       | life is therefore a constantly grating experience.
       | 
       | Marginally related. I paint oils as a hobby, and my studio gets
       | northern light, usually overcast and cloudy, during the day.
       | Differentiating tiny color variations under those conditions is
       | very easy, and in general your objective "pitch perfect"
       | impression of color is also pretty accurate. However, I've
       | painted in the same room at night under a "warm" LED bulb, and
       | been absolutely shocked at how wrong and _blue_ everything turned
       | out when seen in the light of day. Not just that, but the hues I
       | intended to be close to one another are much farther apart than
       | they appeared under LED lighting.
       | 
       | So if lighting conditions can shift not just your perception of a
       | color, but also its relationship to the ones around it, then I
       | think how much more does your screen gamma and range alter that?
       | A fair test would be printed on the exact same Heidelberg in 4
       | colors.
        
         | 01HNNWZ0MV43FF wrote:
         | Swear on me mum I saw a game about kerning and alignment years
         | ago on HN or proggit and of course it's impossible to find on
         | search
        
           | evulhotdog wrote:
           | I recall playing one that had to do with making sure the
           | kerning was aligned...
        
             | pronoiac wrote:
             | Kern Type, perhaps? https://type.method.ac/
        
               | noduerme wrote:
               | This is absolutely brilliant! And an example of why every
               | time I come up with an idea, I should check to see
               | whether someone else had made it before. But brilliant.
               | 
               | I got 100/100 on the first six, except for "Yves" where I
               | got 70/100. I think they're wrong on that one. From any
               | distance, the v should really nestle beneath the Y.
               | 
               | Gonna send this to all my design nerd friends, thank you.
        
           | isp wrote:
           | > I'd like to see a similar study about which text was
           | perfectly kerned, or by how many pixels an element was off-
           | center or misaligned.
           | 
           | > Swear on me mum I saw a game about kerning and alignment
           | years ago on HN
           | 
           |  _Can 't Unsee_ -
           | https://news.ycombinator.com/item?id=27188989 - May 2021 (126
           | comments)
        
         | rcxdude wrote:
         | Yeah, metamers are a trip and a bad LED bulb will really screw
         | with the appearance of colors. If anything, screens are more
         | consistent, but more limited.
        
         | nine_k wrote:
         | Regarding the LED lights: unless you use a lamp with CRI < 90,
         | you see obvious, glaring color distortions, and some colors
         | just "disappear", cannot be seen, because of the lack of a
         | particular spectrum bands. Sadly, most inexpensive LED lamps
         | have CRI around 80, and that light feeld definitely artificial,
         | even if pleasant to the eye. A lamp with CRI 90 is okay, most
         | things look natural, even though you can notice it's not
         | sunlight. A lamp with CRI 95 is very fine, it's practically
         | sunlight, and most tricky colors are visible well. I've never
         | encountered a lamp with CRI, say, 97, but they exist and cost a
         | lot.
         | 
         | (Source: doing object photography.)
        
           | madaxe_again wrote:
           | Surely an incandescent bulb, being a black body radiator, has
           | a CRI of 100? Yes, the temperature is low compared to
           | sunlight, but the rendering is theoretically perfect.
           | 
           | I suppose if you want to get closer to sunlight, you need a
           | carbon arc, which is only a few hundred degrees cooler and
           | again, a perfect black body emitter.
        
             | jerf wrote:
             | Yes. An incandescent bulb is basically the reference for
             | CRI 100. The parent of your poster is explicitly discussing
             | non-incandescent technologies.
        
           | jrapdx3 wrote:
           | IME producing artwork that relies on subtle color
           | relationships requires high quality, "full spectrum"
           | illumination. Natural daylight is the obvious canonical
           | option, but of course not always practical.
           | 
           | My studio gets very little natural light, so selecting
           | optimum light sources is crucial. At one time the most
           | practical option was D50 compliant fluorescent tubes, but
           | these were only fairly acceptable.
           | 
           | Situation with LED lamps is also difficult. Even CRI 90 is
           | inadequate, mainly poor red emission and excessive blue
           | radiation. However D50 compliant LED fixtures are available
           | if somewhat more expensive vs. typical LED lamps.
           | 
           | One vendor worth checking out is Waveform Lighting [0]. They
           | offer several types of products with CRI 95 and CRI 99. I've
           | been using their D50 'shop light' for several months and find
           | it very satisfactory.
           | 
           | [0] https://www.waveformlighting.com
        
         | slowwriter wrote:
         | I got 19/20. Turned off True Tone and cranked the screen
         | brightness. Half the time I didn't know if it was just my eyes
         | playing tricks on me, but it was interesting to notice how the
         | colors seemed completely indiscernible for a few seconds and
         | then suddenly one stood out.
        
         | 0xTJ wrote:
         | I also got 18/20, I was confident on most of them, blinking I
         | found "reset" my vision and made it easier. This was on my
         | relatively comfortable (not too bright) monitor.
        
       | junon wrote:
       | 18/20 :D The only two I couldn't really discern were indeed the
       | ones that I got wrong.
       | 
       | I'd be curious to see some sort of score for each in terms of
       | similarity in terms of human perception, just to get a scale of
       | difficulty.
        
       | js2 wrote:
       | The X-Rite Color Challenge and Hue Test:
       | 
       |  _Are you among the 1 in 255 women and 1 in 12 men who have some
       | form of color vision deficiency? If you work in a field where
       | color is important, or you're just curious about your color IQ,
       | take our online challenge to find out. Based on the Farnsworth
       | Munsell 100 Hue Test, this online challenge is a fun, quick way
       | to better understand your color vision acuity._
       | 
       | https://www.xrite.com/hue-test
       | 
       | (My memory is that the full test used to be online.)
        
         | red75prime wrote:
         | What is "color IQ"? Color identification quotient?
        
       | danw1979 wrote:
       | Definitely not a brag, but I scored 20/20 on my first attempt. Is
       | this because my phone has a particularly good screen that renders
       | colours very accurately?
       | 
       | I'm not in any way involved with art or graphic design or have
       | any experience working with anything to do with colours so I
       | can't chalk it up to experience.
        
       | laserbeam wrote:
       | I honestly felt the grime on my phone's screen had more impact on
       | my accuracy than anything else. Sometimes i'd just rotate my
       | phone and instantly spot the difference after the disks moved.
        
       | throwaway0665 wrote:
       | Towards the end the disk I was looking at would change color and
       | become brighter than the others. I didn't notice until I focused
       | on each one at a time and the "different" one became the one I
       | was looking at.
        
       | bobbyblackstone wrote:
       | Your score: 17 out of 20. Mistakes: 3
        
       | kuratkull wrote:
       | 14 and 15 when doing it relatively quickly. 20/20 when i looked
       | away from the screen for circa 5-10 seconds after each difficult
       | set from 10th one onwards.
        
       | nand_gate wrote:
       | 16/20 speedrun, all my mistakes were within the final 5 weirdly.
       | Boredom?
        
       | dusted wrote:
       | Interesting, it'd be neat if it showed the one you missed.. I had
       | 19 of 20 correct, but I don't know which one I got wrong.. and my
       | wife tells me I'm terrible with colors because I insist most
       | turquoise are greener than they're blue :P
        
       | nottorp wrote:
       | Hmm M3 macbook pro screen, brightness at max.
       | 
       | At about 13/20 they all started to look the same. I even turned
       | off truetone at like 16.
       | 
       | I ended up scoring 15/20, but it's more like 12/20 and 3 lucky
       | guesses.
       | 
       | But then I'm well known to not know or care about subtle colour
       | differences.
        
       | matja wrote:
       | 18/20. I struggled most with the blue ones, but it was actually a
       | purple and a green one that I got wrong - which wasn't what I was
       | expecting! ASUS sRGB OLED at 50% brightness.
        
       | Night_Thastus wrote:
       | 17/20, not too bad. My failures were a blue, purple and brown
       | example.
       | 
       | As others have said, a lot of this also comes down to what
       | monitor and OS you're using, glossy/matte screen type, interior
       | lighting and how everything is configured. This will be a lot
       | easier with an OLED and all but impossible with an old TN panel.
       | And whether HDR is enabled or sRGB mode, etc.
        
       | alyandon wrote:
       | 17/20 for me on Windows 10 with a cheap(ish) 27" 1440p gaming
       | monitor. I really struggled with the purples so I'm wondering if
       | that is more the monitor than my eyeballs.
        
       | kimbernator wrote:
       | 13/20. Didn't analyze the results, but I immediately tried it on
       | my other monitor and got 19/20.
        
       | tristor wrote:
       | Got 18/20, which I credit mostly to my calibrated display and
       | photographer's eye for color. That said, both of the ones I
       | missed were blue and I am wearing glasses that have some blue
       | light filtering, which likely negatively impacted my perception
       | of the blue parts of the color spectrum. It's food for thought as
       | to whether or not I can effectively do post-processing of my
       | photos while wearing glasses like these.
       | 
       | Interesting idea though. I wonder what the distribution looks
       | like?
        
       | Teknoman117 wrote:
       | Apparently I have trouble telling the difference between
       | different shades of pink...
        
       | aaroninsf wrote:
       | I'm not sure there is strong signal about individual performance
       | or human perception in the noise of variation between displays,
       | display settings, and, angle of view.
       | 
       | I have two monitors stacked vertically and this loaded on the top
       | one and I'm fairly sure the latter was as big a factor as actual
       | difference for the least-varying challenges.
        
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