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62706Re: Full Write-up on Embedding the ICC Color Profile into our Jpgs

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  • Rainer
    Jul 3, 2008
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      Hi Neil,

      Thanks. Now If I understood correctly when you open Photoshop you are
      using as working space sRGB ?

      FRam what I knoe about Color Management that is not a good idea. It
      is better to use a working space similar tothe one your monitor is
      able to display and that in most cases is AdobeRGB or maybe BETA RGB
      or Pro Photo color space.

      If you already open you images in sRGB you already clipped some
      colors due to the fact that you are squeezing your image into that
      color space.

      From my point of view it is alaway best to use as much colors as you
      can when you process your images. As last step as you say you convert
      (not assign) the finished image into sRGB

      Microsoft has a nice little application where you can compare in 3D
      the different color spaces and so you can see which color space is
      wider and which one is narrower.

      Here is the link for the download

      http://www.softpedia.com/get/System/OS-Enhancements/Microsoft-Color\
      -Control-Panel-Applet-for-Windows-XP.shtml

      This is very interesting.

      regards Rainer




      >
      > Neil, that's a good question- I don't know, but if you look at the
      > size difference between the embedded versus non-embedded image, it
      is
      > minor. So perhaps it's some sort of processing/interpretation of
      the
      > ICC profile?
      >
      > Steve
      >
      > --- In ccd-newastro@yahoogroups.com, Neil Fleming <neilfleming@>
      wrote:
      > >
      > > I see only subtle differences on my current monitor,
      > > Steve. I suspect that would change from
      > > monitor-to-monitor, though.
      > >
      > > I wonder if the "perfomance impact" is due to some
      > > additional download requirements due to the profile
      > > being embedded, or to the interpretation of the ICC
      > > profile once downloaded. The former, I would guess.
      > >
      > > ...Neil
      > >
      > > --- sc02492 <sc02492@> wrote:
      > >
      > > > Sorry, 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.
      > > >
      > > > Steve
      > > >
      > > > --- In ccd-newastro@yahoogroups.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:
      > > > >
      > > >
      > > http://www.starrywonders.com/rosettewithoutICCsRGB.jpg
      > > > >
      > > > > And here is the same image with an embedded sRGB
      > > > profile tag:
      > > > >
      > > > http://www.starrywonders.com/rosettewithICCsRGB.jpg
      > > > >
      > > > > 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
      > > > >
      > > > >
      > > > > Steve Cannistra
      > > > > http://www.starrywonders.com
      > > > >
      > > > > --- In ccd-newastro@yahoogroups.com, 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
      > > > > image
      > > > > > 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
      > > > correct
      > > > > > 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
      > > > > based
      > > > > > on its tagged colour profile, or (and this may
      > > > be were we differ)
      > > > if no
      > > > > > profile information exists in the image, as
      > > > sRGB.
      > > > > >
      > > > > > Ahh, this "Web Browser Color Management
      > > > Tutorial" page is *very*
      > > > > > informative:
      > > > > >
      > > > >
      > > >
      > >
      >
      http://www.gballard.net/psd/go_live_page_profile/embeddedJPEGprofiles.
      html#
      > > > > >
      > > > > > In amongst all the other goodies it has a roll
      > > > over graphic of an
      > > > sRGB
      > > > > > tagged and untagged image. I can discern no
      > > > difference between the
      > > > > two -
      > > > > > so Firefox3 defaults to assuming an sRGB
      > > > profile. However... when
      > > > I try
      > > > > > 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
      > > > sRGB
      > > > > > map unless the image is tagged as such.
      > > >
      > > === message truncated ===
      > >
      > >
      > > www.flemingastrophotography.com
      > > Direct from Boston - brilliant diamonds in pea soup
      > > Also check out the astro_narrowband Yahoo group!
      > >
      >
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