W3C home > Mailing lists > Public > whatwg@whatwg.org > May 2014

Re: [whatwg] WebGL and ImageBitmaps

From: Rik Cabanier <cabanier@gmail.com>
Date: Sun, 18 May 2014 08:22:33 -0700
Message-ID: <CAGN7qDDO6iDhNUZFLKPAiipncS0UO2gcrR3e4zt0TtM-5iz6UQ@mail.gmail.com>
To: Katelyn Gadd <kg@luminance.org>
Cc: Justin Novosad <junov@google.com>, "whatwg@whatwg.org" <whatwg@whatwg.org>, Glenn Maynard <glenn@zewt.org>, Ian Hickson <ian@hixie.ch>
On Sun, May 18, 2014 at 2:15 AM, K. Gadd <kg@luminance.org> wrote:

> I'd expect that the error might not accumulate for most color values.
> Rounding would potentially kick in once you get the first loss of
> precision.


That doesn't make sense. If this is a shift because of color management, it
should happen for pretty much all values.
I changed my profile to generate wild color shifts and tried random color
values but don't see any changes in any browser.

Could this just be happening with images that have profiles?


> I've only historically seen color shifts upon repeated
> rendering in scenarios where you're losing lots of precision, or
> losing energy (bad RGB <-> HSV conversions, for example) - you don't
> actually need a lot of precision to fix that as long as your
> coefficients are right.
> On Fri, May 16, 2014 at 8:41 PM, Rik Cabanier <cabanier@gmail.com> wrote:
> >
> >
> >
> > On Fri, May 16, 2014 at 3:06 PM, Justin Novosad <junov@google.com>
> wrote:
> >>
> >> On Fri, May 16, 2014 at 5:42 PM, Rik Cabanier <cabanier@gmail.com>
> wrote:
> >>>
> >>>
> >>> Is the Web page not composited in sRGB? If so, it seems the backing
> store
> >>> should be sRGB too.
> >>>
> >>
> >>
> >> The web page is not composited in sRGB. It is composited in the output
> >> device's color space, which is often sRGB or close to sRGB, but not
> always.
> >> A notable significant exception is pre Snow Leopard Macs that use a
> gamma
> >> 1.8 transfer curve.
> >> By the way, sniffing the display color profile through getImageData is a
> >> known fingerprinting technique. This factor alone can be sufficient to
> >> fingerprint a user who has a calibrated monitor.
> >
> >
> > I'm unable to reproduce what you're describing. So, if I fill with a
> color
> > and repeatedly do a getImageData/putImageData, should I see color shifts?
> >
>
Received on Sunday, 18 May 2014 15:22:59 UTC

This archive was generated by hypermail 2.4.0 : Wednesday, 22 January 2020 17:00:20 UTC