5 ms·

Doesn't work for me on Firefox in Windows either. I've tried a number of things and it seems it just doesn't work on Firefox at all.

henriquez 5y ago
Works fine for me in Firefox on Mac.
- mkl 5y ago
  And for me in Firefox 91.4.0 on Android.
  - datak0w 5y ago
    ...and for me, FF 92.0, Ubuntu Linux.
bscphil 5y ago
Do you happen to be using color management by any chance? Believe it or not (because this does seem insane), disabling full color management fixed the site for me. That is, I changed the setting "gfx.color_management.mode" from 1 (manage all colors) back to 2, the default (which only adjusts the colors of images with tagged color profiles). It's bonkers, but I think I understand what's happening here, actually. Relatively recently, Firefox started color correcting the content of <canvas> elements. However, some sites will download an image, load it into a canvas created in Javascript, and then use the data for some other purpose. In particular, Windy downloads a bunch of what appears to be wind data in the form of false color images like [1][2]. Presumably they are using this data to generate the wind animation on the fly in the browser. However, if they're utilizing canvases as part of that process, (my copy of) Firefox is changing the colors out from under them as part of the color management process. Presumably a large enough change in the colors would be enough to break the wind display code completely. [1] https://ims.windy.com/im/v3.0/forecast/ecmwf-hres/2021091012/2021091100/wm_grid_257/3/1/2/wind-surface.jpg https://ims.windy.com/im/v3.0/forecast/ecmwf-hres/2021091012... [2] https://i.imgur.com/z3hQKvs.jpg https://i.imgur.com/z3hQKvs.jpg (backup of [1] in case the link dies)
- 10GBps 5y ago
  Interesting. It still works for me even with gfx.color_management.mode set to 1. Might be hardware differences or maybe desktop (compositing, etc). I'm using XFCE defaults.
  - bscphil 5y ago
    If you don't actually have a profile set, Firefox will (in most cases) treat your screen as sRGB, which means that the colors won't actually be changed.
- tppiotrowski 5y ago
  Wow. Nice find. I also use a canvas to stitch together elevation data encoded as PNGs [1]. Will definitely look into this. The road to bugs is paved with good intentions. [1] https://miro.medium.com/max/1024/0*zRx4LGdE_sxxRip7.png https://miro.medium.com/max/1024/0*zRx4LGdE_sxxRip7.png
- tppiotrowski 5y ago
  Seems dangerous that color correction would not just happen at the display driver level but would modify the values returned by ctx.getImageData. Good fingerprinting technique though!
  - bscphil 5y ago
    I agree, I wish they'd take a different approach.

henriquez 5y ago

Works fine for me in Firefox on Mac.

mkl 5y ago
And for me in Firefox 91.4.0 on Android.
- datak0w 5y ago
  ...and for me, FF 92.0, Ubuntu Linux.

bscphil 5y ago

Do you happen to be using color management by any chance? Believe it or not (because this does seem insane), disabling full color management fixed the site for me. That is, I changed the setting "gfx.color_management.mode" from 1 (manage all colors) back to 2, the default (which only adjusts the colors of images with tagged color profiles). It's bonkers, but I think I understand what's happening here, actually. Relatively recently, Firefox started color correcting the content of <canvas> elements. However, some sites will download an image, load it into a canvas created in Javascript, and then use the data for some other purpose. In particular, Windy downloads a bunch of what appears to be wind data in the form of false color images like [1][2]. Presumably they are using this data to generate the wind animation on the fly in the browser. However, if they're utilizing canvases as part of that process, (my copy of) Firefox is changing the colors out from under them as part of the color management process. Presumably a large enough change in the colors would be enough to break the wind display code completely. [1] https://ims.windy.com/im/v3.0/forecast/ecmwf-hres/2021091012/2021091100/wm_grid_257/3/1/2/wind-surface.jpg https://ims.windy.com/im/v3.0/forecast/ecmwf-hres/2021091012... [2] https://i.imgur.com/z3hQKvs.jpg https://i.imgur.com/z3hQKvs.jpg (backup of [1] in case the link dies)

10GBps 5y ago
Interesting. It still works for me even with gfx.color_management.mode set to 1. Might be hardware differences or maybe desktop (compositing, etc). I'm using XFCE defaults.
- bscphil 5y ago
  If you don't actually have a profile set, Firefox will (in most cases) treat your screen as sRGB, which means that the colors won't actually be changed.
tppiotrowski 5y ago
Wow. Nice find. I also use a canvas to stitch together elevation data encoded as PNGs [1]. Will definitely look into this. The road to bugs is paved with good intentions. [1] https://miro.medium.com/max/1024/0*zRx4LGdE_sxxRip7.png https://miro.medium.com/max/1024/0*zRx4LGdE_sxxRip7.png
tppiotrowski 5y ago
Seems dangerous that color correction would not just happen at the display driver level but would modify the values returned by ctx.getImageData. Good fingerprinting technique though!
- bscphil 5y ago
  I agree, I wish they'd take a different approach.