I went cross-eyed on my screenshot, and I couldnt read the word, but I did notice some artifacts
gus_massa 4 hours ago [-]
Is it possible to modify the webpage to make the pattern of the text go down and the pattern of the background do up?
4 hours ago [-]
sunrunner 7 hours ago [-]
Neat idea.
A friend of mine made a similar animated GIF type captcha a few years ago but based on multiple scrolling horizontal bars that would each reveal their portion of the underlying image including letters, and made a (friendly) bet that it should be pretty hard to solve.
Grabbing the entire set of frames and greyscaling them, doing an average over all of them and then applying a few minor fixups like thresholding and contrast adjustment worked easily enough as the letters were reveleaed in more frames than not (I don't think that would affect the difficulty much though if it were any diffierent). After that the rest of the image was pretty amenable to character recognition.
postalcoder 6 hours ago [-]
Out of sheer curiosity, I put three screenshots of the noise into Claude Opus 4.1, Gemini 2.5 Pro, and GPT 5, all with thinking enabled with the prompt “what does the screen say?”.
Opus 4.1 flagged the message due to prompt injection risk, Gemini made a bad guess, and GPT 5 got it by using the code interpreter.
I thought it was amusing. Claude’s (non) response got me thinking - first, it was very on brand, second, that the content filter was right - pasting images of seemingly random noise into a sensitive environment is a terrible idea.
apricot 35 minutes ago [-]
> pasting images of seemingly random noise into a sensitive environment is a terrible idea
Nice one, the good (great?) thing is that you can save this as a plain old html and you've got the whole code :-)
It hasn't got any type of license included or any other info as comments, so perhaps the creator or the OP can let us know.
Syntonicles 12 hours ago [-]
I first saw this effect in a video from Branta Games.
If anybody implements that to antiscrenshot some sensitive data, somebody else will use another phone, a tablet or a camera to record a video of it. Nice idea though.
gwbas1c 2 hours ago [-]
It's just adding friction: Someone determined will figure out a way to get the text.
Sometimes friction is enough.
jonathaneunice 3 hours ago [-]
Or the same one.
While a screencap image hides the message, a screencap video shows it perfectly well.
outsideoftime 2 hours ago [-]
[dead]
jerf 1 hours ago [-]
On my Chrome-descended browser, the initial screen is populated by something that appears to be some sort of downsampled grid image, resulting in black and white, but also various shades of grey. However the scrolling text is pure black and white. It also seems the canvas is persistent, so the result is that text on the canvas is leaving a shadow for me, where I can still read the shadow. Somehow the initial noise is not coming out as just black and white pixels.
landgenoot 2 hours ago [-]
I think there are usecases for this.
Some countries switched to identity apps instead of plastic identity cards. You could make sensitive data non-screenshottable and non-photographable.
The hotel you are checking in doesn't need to know your DOB, length, SSN, birth place, validity and document number. But they will demand a photo of the ID anyway.
jlokier 35 minutes ago [-]
> You could make sensitive data non-screenshottable and non-photographable.
That made me curious, so I took a photo of my laptop screen running this page.
With default camera settingse, the text wasn't visible to me in the photo on my phone screen.
However, setting the exposure time manually to 0.5s, the text came out white on a noisy background and I could easily read it on the phone screen.
I would not be surprised if the default camera settings photo could be processed ("enhance!") to make the text visible, but I didn't try.
landgenoot 3 minutes ago [-]
I think it also depends on the response time of the display.
This one is actually more sophisticated because it doesn't rely on scrolling pixels like the OP. So the object doesn't just disappear in screenshots, but also when the animation stops moving! So you can't actually display text that stands still, like the "hello" in the OP.
optionalsquid 2 hours ago [-]
I'm not sure I follow. Couldn't you display text that stands still by (re)drawing the outline of the text repeatedly? It would essentially be a two frame animation
cubefox 2 hours ago [-]
I believe the algorithm in the video works by flipping the pixel color when the pixel changes from foreground (some shape) to background, or from background to foreground. If the shape doesn't move, there is no such change, so it disappears.
In the OP the foreground pixels continuously change (scrolling in this case) while the background doesn't change. That's a different method of separating background and foreground.
zem 7 hours ago [-]
thanks, that's also the best explained one!
Aeolun 7 hours ago [-]
This should have an epilepsy warning. Or something of that kind. It certainly made me feel sick.
injidup 6 hours ago [-]
This is more a curious question for those affected by epilepsy. If you know you are triggered by such things how long an exposure is required to trigger an effect. Are you able notice that media may be triggering and simply close it or is exposure and triggering almost instantaneous?
a3w 5 hours ago [-]
I saw the game using this rendering weeks ago, looked okay. Now I saw a font and tried to hold on to the edges while reading it, and yes, somehow this made me more (sea) sick. Strange.
Perhaps faces would be strongest in terms of reaction.
dorianmonnier 7 hours ago [-]
Oh yes please add a warning. My brain is burning right now!
kemayo 12 hours ago [-]
This makes me feel motion-sick, which is kind of impressive because I'm normally not easily susceptible to that.
dylan604 12 hours ago [-]
My eyes went straight into seeing 3D image mode. It's the easiest one I've seen yet! /s
hnlmorg 4 hours ago [-]
Hello fellow person from the 90s. mine eyes did the same too.
RedShift1 11 hours ago [-]
Heh my eyes felt like they started bleeding
quietfox 8 hours ago [-]
"The text disappears..."
And my eyesight with it
dylan604 12 hours ago [-]
Has anyone tried a long exposure to see if the motion smears into something discernible? Obviously harder to expose a bright screen without some ND since the shutter speed is the phone's main exposure control
That's what I was expecting to see. I didn't have a mount for my phone handy, to try it. The exporting of frames from a video is a good compromise though. nice one
shawnz 10 hours ago [-]
Perhaps this technique could be defeated by scrolling the background in the opposite direction as the text
lodovic 10 hours ago [-]
If you zoom out to 25 % the text is clearly visible and screenshottable.
EvgeniyZh 8 hours ago [-]
Probably the lower frequencies of noise are not matched? Not sure if the frequencies of the order of movement frequency can actually be matched
dasil003 11 hours ago [-]
How do you take a “long exposure” screenshot? Isn’t every screenshot a perfect digital copy of a single frame or a full on video?
dylan604 11 hours ago [-]
Clearly, I meant using a camera, and I'm guessing you knew that too
dice 10 hours ago [-]
Not the parent but that was not at all clear to me. I immediately thought of taking multiple successive instantaneous screenshots and then stacking them. I'm not sure I would have thought of using a camera within a few minutes to an hour, it's not a tool I would ever reach for normally.
catlifeonmars 10 hours ago [-]
I just did this with 50% transparency. It works
DonHopkins 4 hours ago [-]
Oh, so your screenshot utility has "long exposure" and an "ND" filter and "shutter speed" controls, just like a phone's camera? What kind of screenshot utility simulates optical camera effects? What purpose does that serve? Care to share a link to it?
>Obviously harder to expose a bright screen without some ND since the shutter speed is the phone's main exposure control
Neat! I've seen stuff like this that works as a magic eye thing. So you cross your eyes (or make them parallel, depending on the type of image) and it makes a 3d animation appear in front of the page.
cal85 3 hours ago [-]
I’d like to see an example!
oniony 7 hours ago [-]
I don't see any text: just a scrolling down screen of random black/white pixels.
rnhmjoj 6 hours ago [-]
It seems to depend on reading pixels from a canvas. This is commonly used for fingerprinting users on the web, so you have to disable some privacy plugins.
Anonyneko 5 hours ago [-]
As soon as I read the title I knew it would be akin to "Bad Apple that disappears when you pause it"
This would make for a great effect for a technothriller. Like a cyber ransom or something like that.
creata 4 hours ago [-]
Fun!
I always wanted to make text that couldn't be recorded with a video recorder, but that doesn't seem possible.
Maybe if you knew the exact framerate that the camera was recording at, you could do the same trick, but I don't think cameras are that consistent.
jiehong 4 hours ago [-]
I have to admit it's a pretty cool idea.
At first I was worried that there was a (stupid) API in web browsers just like on mobiles to prevent users from screenshotting something by blanking the screen in the screenshot.
wink 7 hours ago [-]
Doesn't even show anything on LibreWolf, probably disabled WebGL as usual. I thought it was a nice error screen, but apparently it was intended, just without the text :P
creatonez 7 hours ago [-]
Seems to work if you disable canvas fingerprinting protection.
zikero 12 hours ago [-]
Another idea I had with this concept is to make an LLM-proof captcha. Maybe humans can detect the characters in the 'motion' itself, which could be unique to us?
- The captcha would be generated like this on a headless browser, and recorded as a video, which is then served to the user.
- We can make the background also move in random directions, to prevent just detecting which pixels are changing and drawing an outline.
- I tried also having the text itself move (bounce like the DVD logo). Somehow makes it even more readable.
I definitely know nothing about how LLMs interpret video, or optics, so please let me know if this is dumb.
xandrius 6 hours ago [-]
I don't think we need more capable people thinking of silly captchas.
12 hours ago [-]
pwdisswordfishz 4 hours ago [-]
Take N screenshots, XOR them pairwise, OR the results, then perform normal OCR.
squigz 11 hours ago [-]
As if captchas aren't painful enough for visually impaired users...
p0w3n3d 5 hours ago [-]
This idea has made me think of another subject - would it be possible to overload a face / car plate scanning camera by using a pattern, like qr code for exampl? Or a jacket made of qr codes?
Cool. I used the Windows snipping tool and just screen-recorded it.
Izkata 12 hours ago [-]
Firefox on Android seems to just be a static image, I can't see any text.
creatonez 7 hours ago [-]
Probably the result of canvas fingerprinting protection configured in your `about:config`? With a default profile it seems to work fine on Firefox for Android.
Izkata 3 hours ago [-]
I haven't changed any of that on here.
Looks like I consistently get just the static image when I open in a new tab then switch to it, but then if I refresh the page without switching tabs it'll show the animation.
I think further obfuscation could be possible by uglifying the script and providing a SVG path that stores the text as some vector image.
Self modifying code could be useful too, to delete the SVG data once it is in the canvas.
I fully expect this to still be defeated by AI though, such is my presumption that AI is smarter than me, always. It won't care about uglification and it would just laugh to itself at my humble efforts to defeat Skynet.
Regarding practical applications, nowadays kids sell weed online quite brazenly on platforms such as Instagram. Prostitutes also sell their services on Telegram. It is only a matter of time before this type of usage gets clamped down on, so there may come a time when this approach will be needed to thwart the authorities.
shrikant 6 hours ago [-]
Could someone please post what this disappeared bit is supposed to look like? Looks legible to me when I screenshot and open in Preview on MacOS 15.6.1 (Firefox).
grumbel 5 hours ago [-]
You are probably browsing with zoom, that seems to screw up the up rendering and makes the background and text look different. It should be just black&white random pixel noise for both background and foreground, without motion the text becomes invisible, as it blends with the background.
giamma 7 hours ago [-]
It's a nice effect, but I don't think it's usable in practice, because it's not accessible for visually impaired users: not enough contrast between foreground text and background
tedggh 4 hours ago [-]
I uploaded two images to ChatGPT and asked it to XOR them and give me the result in text.
johnjreiser 4 hours ago [-]
Appreciate that it handles emoji as well.
Can't distinguish between smileys though.
johnjreiser 4 hours ago [-]
I also appreciate that Hn removes emojis from comments. :'(
EGreg 1 hours ago [-]
This is good but I feel it can somehow be made better!
I like the idea of motion revealing things out of randomness and screenshots are random.
You can just take a screencast though hehe
benob 3 hours ago [-]
a good benchmark for video understanding in IA
QuiCasseRien 8 hours ago [-]
Even is some have found a workaround, this is a cool feature
amelius 7 hours ago [-]
Yeah but the randomness may produce all kinds of NSFW stuff ...
Also, it's even harder to read than most captchas.
But fun idea, it was nice to see.
bix6 13 hours ago [-]
Ha cool! How’s it work?
Lalabadie 12 hours ago [-]
The only way to see the text is in the movement. The pattern across any single frame is entirely random noise.
thaumasiotes 9 hours ago [-]
> The pattern across any single frame is entirely random noise.
This is untrue in at least one sense. The patterning within the animated letters cycles. It is generated either by evaluating a periodic function or by reading from a file using a periodic offset.
giveita 9 hours ago [-]
Can't it be continuous random noise added at the top and then moved down each frame.
Roughly you create another full size rect. On each frame add a random pixel on row 1 and shift everything down.
Make that rest a layer below the top one which has Hello cut out as transparent.
In any single frame the result is random noise.
thaumasiotes 9 hours ago [-]
You could do that, but that's not what the page is doing.
You don't even need to maintain the approach of having the pattern within the text move downwards over time. You could redraw it every frame with random data, as if it was television static. It would still be easy to read, as long as the background stayed fixed.
For what it's worth, there are some websites that embed some crazy shit when you screenshot. On reddit, r/CenturyClub will fill your background with a slightly off-white version of your username so that they can identify leakers, and I'm not certain how exactly they do it.
bilsbie 3 hours ago [-]
Ultimately people will just take photos of the screen. Seems like you’re just annoying people.
I feel like there’s an ethical issue. If something is on my screen I own it. I know the law doesn’t agree but it feels right to me.
sarreph 3 hours ago [-]
The point is that it's noise and you can't "capture" a still image of the text / information (relies on motion to be viewable).
elAhmo 8 hours ago [-]
If you blink really fast, the text almost disappears.
altcognito 12 hours ago [-]
Fun side effect: staring at the letters for a bit makes the rest of the image move.
magios 7 hours ago [-]
firefox on linux with a bunch of css stuff set to defaults or none !important shows a static image
domatic1 6 hours ago [-]
but screen recording works :)
tamimio 6 hours ago [-]
In your phone, just record the screen, then drag the player to see how every still pic blend in within the surroundings, but as soon as it moves it shows up.
cryptoz 13 hours ago [-]
Had a lot of fun trying to break this. Turns out you can screenshot real easily by zooming out. Maybe there are other ways but I stopped trying :)
vunderba 12 hours ago [-]
yeah - I actually was initially confused since I wasn't having any issues screenshotting it but had forgotten that I have the default site zoom set to ~65%.
sans_souse 12 hours ago [-]
Not sure what you mean - I can screenshot it freely that's not the point the point is if you look then at the screenshot you cant discern the text because its a single frame now
This is on MacOS 15.6, Chromium (BrowserOS), captured with the OS' native screenshot utility. Since I was asked about the zoom factor, I now tried simply capturing it at 100% and it was still perfectly readable...
I guess the trick doesn't work on this browser.
dylan604 12 hours ago [-]
I zoomed out to 90% and could make out something was there but wasn't easy to read. Zooming out further went back to just being noise. I also tried zooming in but with no success. What zoom level did you use and I guess we have to ask the standard what browser/version/OS/etc?? My FFv142 on macOS never took a screen grab like you did
chii 9 hours ago [-]
This is really interesting - because it means the "randomness" is different between the text and the background, and when you zoom out enough, the eye can distinguish it?
vunderba 9 hours ago [-]
hmmm I think it's probably just an aliasing / canvas drawing issue. When I bring a screenshot in heavily zoomed out 33% - the pixels comprising the "HELLO" shape have a significantly higher luminance than the rest of the background.
dwg 12 hours ago [-]
Zooming out before taking screenshot and the text is no longer obfuscated. I tried and confirmed it works. In fact, the text is perhaps even more readable than the original.
anigbrowl 12 hours ago [-]
It depends how fast or slow your GPU is. I tried it and saw the effect you described, but within a second or two it started moving and was obscured again. Obviously you could automate the problem away.
dylan604 12 hours ago [-]
Mine freezes the animation on zoom change. Not sure you could automate against that
anigbrowl 10 hours ago [-]
What I meant was that even if it only freezes for a second, you could automate the screenshots to be captured during that time instead of trying to beat the clock manually
davidgerard 9 hours ago [-]
Screnshotted fine in Xfce.
kps 12 hours ago [-]
The text reappears when I screenshot it twice.
UltraSane 12 hours ago [-]
Seems trivial to diff multiple screenshots to identify what parts move. Or just use a compression algorithm to do the same.
dazzlevolta 10 hours ago [-]
Would 2 screenshots be enough, I wonder?
boothby 10 hours ago [-]
Yeah, the letters are big enough, an xor shows the text quite clearly.
1oooqooq 4 hours ago [-]
"you cannot screenshot this already illegible mess of white noise"
hbbio 10 hours ago [-]
Coinbase was hacked for $400M when literally someone from outsourced support services was taking screenshots on their phone!
The culprit had more than 10k photos of all security details for thousands of wealthy customers.
gloosx 8 hours ago [-]
If it's even true someone from outsourced support has access to some sensitive security details then using this dumpster is almost like throwing your money out of the window.
Rendered at 15:43:24 GMT+0000 (Coordinated Universal Time) with Vercel.
Lighten, Screen, Addition, Darken, Multiply, Linear burn, Hard Mix, Difference, Exclusion, Subtract, Grain Extract, Grain Merge, or Luminance.
https://ibb.co/DDQBJDKR
You actually don't need any image editing skill. Here is a browser-only solution:
1. Take two screenshots.
2. Open these screenshots in two separate tabs on your browser.
3. Switch between tabs very, very quickly (use CTRL-Tab)
Source: tested on Firefox
A friend of mine made a similar animated GIF type captcha a few years ago but based on multiple scrolling horizontal bars that would each reveal their portion of the underlying image including letters, and made a (friendly) bet that it should be pretty hard to solve.
Grabbing the entire set of frames and greyscaling them, doing an average over all of them and then applying a few minor fixups like thresholding and contrast adjustment worked easily enough as the letters were reveleaed in more frames than not (I don't think that would affect the difficulty much though if it were any diffierent). After that the rest of the image was pretty amenable to character recognition.
Opus 4.1 flagged the message due to prompt injection risk, Gemini made a bad guess, and GPT 5 got it by using the code interpreter.
I thought it was amusing. Claude’s (non) response got me thinking - first, it was very on brand, second, that the content filter was right - pasting images of seemingly random noise into a sensitive environment is a terrible idea.
BLIT protection. https://www.infinityplus.co.uk/stories/blit.htm
Only if your rendering libraries are crap.
They even provide the source code for the effect:
https://github.com/brantagames/noise-shader
https://upload.wikimedia.org/wikipedia/en/a/ab/AnyMinuteNow....
https://www.youtube.com/watch?v=Bg3RAI8uyVw
The effect is disrupted by introducing rendering artifacts, by watching the video in 144p or in this case by zooming out.
I'd love to know the name of this effect, so I can read more about the fMRI studies that make use of it.
What I've found so far:
Random Dot Kinematogram
Perceptual Organization from Motion (video of Flounder camouflage)
https://www.youtube.com/watch?v=2VO10eDIyiE
Sometimes friction is enough.
While a screencap image hides the message, a screencap video shows it perfectly well.
Some countries switched to identity apps instead of plastic identity cards. You could make sensitive data non-screenshottable and non-photographable.
A modern variant to the passport anti identity fraud cover: https://merk.anwb.nl/transform/a9b4e52a-9ba1-414b-b199-29085...
The hotel you are checking in doesn't need to know your DOB, length, SSN, birth place, validity and document number. But they will demand a photo of the ID anyway.
That made me curious, so I took a photo of my laptop screen running this page.
With default camera settingse, the text wasn't visible to me in the photo on my phone screen.
However, setting the exposure time manually to 0.5s, the text came out white on a noisy background and I could easily read it on the phone screen.
I would not be surprised if the default camera settings photo could be processed ("enhance!") to make the text visible, but I didn't try.
On iPhone: screenrecord. Take screenshots every couple seconds. Overlay images with 50% transparency (I use Procreate Pocket for this part)
In the OP the foreground pixels continuously change (scrolling in this case) while the background doesn't change. That's a different method of separating background and foreground.
Perhaps faces would be strongest in terms of reaction.
>Obviously harder to expose a bright screen without some ND since the shutter speed is the phone's main exposure control
https://en.wikipedia.org/wiki/Neutral-density_filter
https://en.wikipedia.org/wiki/Shutter_speed
"ffs".
https://unscreenshottable.vercel.app/?text=Bonjour
https://www.youtube.com/watch?v=bVLwYa46Cf0
And another version of this, using apples instead of white noise
https://www.youtube.com/watch?v=r40AvHs3uJE
I always wanted to make text that couldn't be recorded with a video recorder, but that doesn't seem possible.
Maybe if you knew the exact framerate that the camera was recording at, you could do the same trick, but I don't think cameras are that consistent.
At first I was worried that there was a (stupid) API in web browsers just like on mobiles to prevent users from screenshotting something by blanking the screen in the screenshot.
- The captcha would be generated like this on a headless browser, and recorded as a video, which is then served to the user.
- We can make the background also move in random directions, to prevent just detecting which pixels are changing and drawing an outline.
- I tried also having the text itself move (bounce like the DVD logo). Somehow makes it even more readable.
I definitely know nothing about how LLMs interpret video, or optics, so please let me know if this is dumb.
https://en.wikipedia.org/wiki/Dazzle_camouflage
Looks like I consistently get just the static image when I open in a new tab then switch to it, but then if I refresh the page without switching tabs it'll show the animation.
I think further obfuscation could be possible by uglifying the script and providing a SVG path that stores the text as some vector image.
Self modifying code could be useful too, to delete the SVG data once it is in the canvas.
I fully expect this to still be defeated by AI though, such is my presumption that AI is smarter than me, always. It won't care about uglification and it would just laugh to itself at my humble efforts to defeat Skynet.
Regarding practical applications, nowadays kids sell weed online quite brazenly on platforms such as Instagram. Prostitutes also sell their services on Telegram. It is only a matter of time before this type of usage gets clamped down on, so there may come a time when this approach will be needed to thwart the authorities.
I like the idea of motion revealing things out of randomness and screenshots are random.
You can just take a screencast though hehe
Also, it's even harder to read than most captchas.
But fun idea, it was nice to see.
This is untrue in at least one sense. The patterning within the animated letters cycles. It is generated either by evaluating a periodic function or by reading from a file using a periodic offset.
Roughly you create another full size rect. On each frame add a random pixel on row 1 and shift everything down.
Make that rest a layer below the top one which has Hello cut out as transparent.
In any single frame the result is random noise.
You don't even need to maintain the approach of having the pattern within the text move downwards over time. You could redraw it every frame with random data, as if it was television static. It would still be easy to read, as long as the background stayed fixed.
I feel like there’s an ethical issue. If something is on my screen I own it. I know the law doesn’t agree but it feels right to me.
This is on MacOS 15.6, Chromium (BrowserOS), captured with the OS' native screenshot utility. Since I was asked about the zoom factor, I now tried simply capturing it at 100% and it was still perfectly readable...
I guess the trick doesn't work on this browser.
The culprit had more than 10k photos of all security details for thousands of wealthy customers.