Beijing National Stadium - satellite photo

Discussion in 'Digital Photography' started by David J Taylor, Aug 13, 2008.

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  1. David J Taylor

    Böwser Guest

    Böwser, Aug 13, 2008
    #2
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  2. David J Taylor

    Frank Guest

    Frank, Aug 13, 2008
    #3
  3. David J Taylor

    Robert Coe Guest

    On Wed, 13 Aug 2008 17:30:32 -0500, Ron Hunter <> wrote:
    : Allen wrote:
    : > Frank wrote:
    : >> the chinese somehow censored the colour! ;-)
    : >>
    : >> bye
    : >>
    : >>
    : >> frank
    : >>
    : >>
    : >>
    : >> http://tvc15.blogs.com/
    : >>
    : >>
    : > But is it a disguised missile silo? If it were in Iraq, Duh Bya would
    : > be shouting "There's the proof! There's the proof!"
    : > Allen
    : Please keep your politics to yourself.

    Why? Does the truth about the Republican Agenda offend your sensibilities?
    You're not planning to vote for Cain McLain, are you? ;^)

    Bob
    Robert Coe, Aug 14, 2008
    #4
  4. Rita Berkowitz <> wrote:
    > B?wser wrote:


    >>>> http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=18114
    >>>
    >>> Looks more like a dirty public toilet seat than a bird's nest. Cool
    >>> pic.

    >>
    >> A subject of expertise, no doubt, for you.
    >>
    >> Pretty telling reply, dontcha think?


    > Let's see? Air pollution that limits visibility to less than 100-meters,


    Just what distance do you think the photograph you are "discussing"
    was taken from?

    --
    Chris Malcolm DoD #205
    IPAB, Informatics, JCMB, King's Buildings, Edinburgh, EH9 3JZ, UK
    [http://www.dai.ed.ac.uk/homes/cam/]
    Chris Malcolm, Aug 14, 2008
    #5
  5. John McWilliams wrote:
    []
    > Wonder why photo is in B+W?


    Most satellite data is single channel - less bandwidth and perhaps higher
    resolution - colour is false-colour obtained by combining separate RGB
    channels. If those channels approximate to a human eye response, the
    result is natural colour images. Usually, though, you would expect a
    three-channel scan for "public consumption" images. Perhaps in this case
    the commercial image /is/ in colour?

    David
    David J Taylor, Aug 14, 2008
    #6
  6. Ron Hunter wrote:
    > David J Taylor wrote:
    >> John McWilliams wrote:
    >> []
    >>> Wonder why photo is in B+W?

    >>
    >> Most satellite data is single channel - less bandwidth and perhaps
    >> higher resolution - colour is false-colour obtained by combining
    >> separate RGB channels. If those channels approximate to a human eye
    >> response, the result is natural colour images. Usually, though, you
    >> would expect a three-channel scan for "public consumption" images.
    >> Perhaps in this case the commercial image /is/ in colour?
    >>
    >> David
    >>
    >>

    > Interesting that you call the way your eyes sense color, and the way
    > almost all digital cameras do it, as 'false color'.


    Ron,

    I'm more used to dealing with satellite data where the colour is produced
    from channels with sensitive wavelengths far removed from those of the
    human eye - hence the colour is false. Even with the Digital Globe
    satellite, I would expect that the RGB channels are not chosen to
    specifically match the colour standards in digital photography RGB space
    (sRGB, ARGB etc.), so "approximate colour" might be a better description
    than "false-colour". But you are right in that all digital photography is
    "approximate colour".

    If anyone has an example which is not "approximate", let him speak now!

    Cheers,
    David
    David J Taylor, Aug 14, 2008
    #7
  7. David J Taylor <-this-bit.nor-this-bit.co.uk> wrote:
    > Ron Hunter wrote:
    >> David J Taylor wrote:
    >>> John McWilliams wrote:
    >>> []
    >>>> Wonder why photo is in B+W?
    >>>
    >>> Most satellite data is single channel - less bandwidth and perhaps
    >>> higher resolution - colour is false-colour obtained by combining
    >>> separate RGB channels. If those channels approximate to a human eye
    >>> response, the result is natural colour images. Usually, though, you
    >>> would expect a three-channel scan for "public consumption" images.
    >>> Perhaps in this case the commercial image /is/ in colour?
    >>>
    >>> David
    >>>
    >>>

    >> Interesting that you call the way your eyes sense color, and the way
    >> almost all digital cameras do it, as 'false color'.


    > Ron,


    > I'm more used to dealing with satellite data where the colour is produced
    > from channels with sensitive wavelengths far removed from those of the
    > human eye - hence the colour is false. Even with the Digital Globe
    > satellite, I would expect that the RGB channels are not chosen to
    > specifically match the colour standards in digital photography RGB space
    > (sRGB, ARGB etc.), so "approximate colour" might be a better description
    > than "false-colour". But you are right in that all digital photography is
    > "approximate colour".


    > If anyone has an example which is not "approximate", let him speak now!


    A most amusing exercise with your digital camera is to split a sunbeam
    with a glass prism and catch the resulting spectrum on a white piece
    of paper. Annotate the paper in pencil with where you consider the
    boundaries between the colours are. Then photograph it all with your
    digital camera and look at the result :)

    --
    Chris Malcolm DoD #205
    IPAB, Informatics, JCMB, King's Buildings, Edinburgh, EH9 3JZ, UK
    [http://www.dai.ed.ac.uk/homes/cam/]
    Chris Malcolm, Aug 14, 2008
    #8
  8. Ron Hunter wrote:
    []
    > I am sure there are instruments that can measure color to an exact
    > wavelength, but the human eye, the only reference I really can depend
    > on, isn't one of them, being, inherently analog. I am familiar with
    > colors being manipulated to distinguish, for instance, growing
    > vegetation, from dead vegetation, which are called 'false color' to
    > denote this manipulation. Perhaps 'visible wavelengths' would be a
    > better designation than 'approximate color' in this case (or colour,
    > if you prefer).


    Yes, Ron, "visible wavelength" sensors could be a suitable description.
    Be aware, though, that satellites sometimes have more than just the three
    RGB visible wavelength colour sensors we are used to with digital cameras.
    How do you process more than three colours to a three colour display
    without some element of approximation?

    Cheers,
    David
    David J Taylor, Aug 14, 2008
    #9
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