62701Re: Full Write-up on Embedding the ICC Color Profile into our Jpgs
- Jul 2, 2008Sorry, Freudian slip <g>:
"With color management turned OFF, open them side by side to see if
there is a difference, and then you can assess this more objectively."
I obviously meant with color management turned ON. Sorry to confuse.
--- In email@example.com, "sc02492" <sc02492@...> wrote:
> Excellent post, and I completely agree. I made the point on another
> website that I could see no difference in my own astroimages on my
> website (processed in sRBG space, which most of us do), whether or not
> color management was activated in Firefox 3. Certainly for other
> color spaces like Adobe RGB, a color managed browser would be useful,
> but most of us don't process in Adobe RGB color space. Paul makes the
> excellent point that tagging an astroimage in anything other than sRGB
> color space should be avoided, since it will introduce even more
> variability in how our astroimages appear to others, unless everyone
> decides to use a color managed browser.
> That said, all of the images on my website are indeed tagged with sRGB
> profiles- this has been my practice all along, the main reason being
> that if anyone wanted to open an image in Photoshop, I wanted to
> ensure that it looked the same to them (assuming that their monitor is
> well calibrated). But if there is also a minor benefit to tagging an
> image in sRGB color space, with respect to viewing it in a web
> browser, it certainly will do no harm to include it (see end of post
> to determine if it makes a difference for you).
> Since I cannot see a difference in astroimaging sites with color
> management turned on or off, I'm keeping mine off for now (Firefox 3).
> The performance hit with color management turned on, no matter how
> small, is irritating to me since the images themselves look no
> different on my monitor. However, I would advise people to see for
> themselves whether astroimages on various websites look different on
> their own monitors, and do whatever they think is best. Don't assume
> anything until you've tried it. You can feel free to use my website
> as a test, since I can assure you that all of the images were
> processed in sRGB color space.
> Finally, people may find this useful to test their own system. Here
> is one of my own images, processed in sRGB color space in Photoshop
> but uploaded untagged:
> And here is the same image with an embedded sRGB profile tag:
> With color management turned OFF, open them side by side to see if
> there is a difference, and then you can assess this more objectively.
> Again, this may be monitor and OS dependent, so your mileage may
> vary, but it wouldn't surprise me if most see no appreciable difference.
> Steve Cannistra
> --- In firstname.lastname@example.org, Paul Beskeen <yahoo@> wrote:
> > Hi Neil,
> > Neil Fleming wrote:
> > > --- Paul Beskeen <yahoo@> wrote:
> > >> Hi Neil,
> > >>
> > >> 1) I don't understand what benefit you would get if
> > >> you continue to save
> > >> in sRGB colour space (as suggested by your workflow)
> > >> but with "color
> > >> profile" ticked. The default for all browsers is
> > >> sRGB.
> > >
> > > Think of it this way. The sRGB color space represents
> > > the range of values that you *can* work with. Like
> > > the range of choices on a bingo card.
> > >
> > > Unless you are viewing an image with the color profile
> > > embedded, *and* your program will accommodate that
> > > mapping, you will see "uncontrolled" results rather
> > > than that the author intended. "B5" on your bingo
> > > card could be "B7" on another's.
> > >
> > > Just take a look at the ICC example in the original
> > > e-mail. The authors picked (on purpose) an extreme
> > > example, but it illustrates the point well.
> > I don't mean to be argumentative here, and I'm certainly no expert in
> > colour management, but I guess it comes down to the question "do ICC
> > aware applications by default gamut map to sRGB whether or not the
> > is tagged as sRGB?". [The default for browsers, monitors, HDTV's,
> etc is
> > to use sRGB colour space. Most don't succeed very well so
> calibration is
> > advisable for accurate display]
> > If the person viewing your image has profiled their monitor, then the
> > graphic card LUT tables will be set at startup to adjust to the
> > gamma and white point. If a program is ICC enabled then in addition
> > gamut mapping will be used to render the image's colours correctly
> > on its tagged colour profile, or (and this may be were we differ)
> > profile information exists in the image, as sRGB.
> > Ahh, this "Web Browser Color Management Tutorial" page is *very*
> > informative:
> > In amongst all the other goodies it has a roll over graphic of an
> > tagged and untagged image. I can discern no difference between the
> two -
> > so Firefox3 defaults to assuming an sRGB profile. However... when
> > the same with Safari I can see a subtle difference! So Safari
> doesn't do
> > sRGB gamut mapping unless it is tagged as sRGB! From comments on the
> > page it appears that Vista's new colour management system also
> > automatically defaults to sRGB if an image is not tagged. Given that
> > sRGB is the standard for the web I'm surprised that Safari doesn't
> > map unless the image is tagged as such.
> > Bottom line: Tagging as sRGB certainly does no harm and in some
> > circumstances can lead to a more accurate rendering. Your advice is
> > completely correct :)
> > >> 2) If you save in an alternative colour space - such
> > >> as Adobe RGB, then
> > >> won't people without ICC enabled browsers see some
> > >> very strange effects?
> > >
> > > I wouldn't necessarily call it "extreme", but there
> > > would be minor differences. Adobe RGB is better
> > > adapted to printing, with its wider gamut than sRGB.
> > > Some of the colors would be shifted to something you
> > > can see. What you see on your monitor would not what
> > > would be printed, unless you have a high-end monitor
> > > like an Eizo, one that is capable of displaying the
> > > full Adobe 1998 gamut.
> > Tagging images for web display with anything other than sRGB should
> > definitely be avoided. The vast majority of web browsers are not
> > managed & displays not profiled - an image that uses AdobeRGB or any
> > profile other than sRGB will definitely render incorrectly.
> > To demonstrate this issue go to the section "ADOBE RGB (1998) 2.2
> > gamma", and try the rollover graphic.
> > Cheers, Paul.
> > > ...Neil
> > >
> > > www.flemingastrophotography.com
> > > Direct from Boston - brilliant diamonds in pea soup
> > > Also check out the astro_narrowband Yahoo group!
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