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Re: Fwd: White Balance in Panoramas

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  • luc.villeneuve
    I import my images in Aperture color balance ONE image with the very efficient tools in Aperture then copy the settings from this image and paste the settings
    Message 1 of 23 , Feb 28, 2008
      I import my images in Aperture color balance ONE image with the very efficient tools in
      Aperture then copy the settings from this image and paste the settings to the other images.

      Time consuming is a relative concept.
    • Georgia Real Tours
      ... Hi Nelson, I m not sure exactly how to mix white balances under different lighting conditions, but I do have a suggestion that might lead to something
      Message 2 of 23 , Feb 28, 2008
        On 2/28/08, Nelson Mendes <nmendes@...> wrote:
        >
        > Hi, I work mainly with indoor panoramas, and what's been really a time
        > consuming effort in the creation of the panoramas is the white balance
        > compensation.
        > The problem is that usually I have incandescent light inside and sun light
        > on the outside, and that creates bluish tones (or redish tones depending on
        > the white balance setting) on some areas of the panorama (like in open doors
        > that lead to rooms with a great amount of outside light).

        Hi Nelson,

        I'm not sure exactly how to "mix" white balances under different
        lighting conditions, but I do have a suggestion that might lead to
        something useful. I just got a WhiBal set, and haven't yet had an
        opportunity to test it out well enough. However, my idea was to
        choose a single light source to do the rest of the pano's white
        balance. In your case with a WhiBal, here's what I'd do: I'd shoot
        the WhiBal under each light source. I'd then create a series of RAW
        files optimized for each white balance. Once I did that, I'd create a
        pano (strips, cubes, equi, etc.) for each optimized white balance.
        After that, there's several different methods of combining them.

        All of that may sound like a lot of time-consuming work, but I don't
        think it would be. You'd simply be shooting an extra shot for each
        light source and making an equivalent number of RAW sets as are
        light-source shots. And if you are using Bibble, you don't even have
        to do that. Additionally, once you have the required CPs for one pano
        you can batch stitch the rest.

        If you don't know what I WhiBal is (and I don't expect you to, I just
        found out about it not long ago) it is a neutral color board whose
        color value is known. You can find out more about it at
        http://www.rawworkflow.com/products/whibal/index.html
        <http://www.rawworkflow.com/products/whibal/index.html> While I
        haven't yet tried it in a pano, it certainly has helped with regular
        photos!

        Cheers,
        Robert~
        --
        Mid GA: 478-599-1300
        ATL: 678-438-6955
        garealtours.com
      • Eric O'Brien
        I have been including a neutral gray ( grey ) target every time I shoot a panorama, for quite a while. Certainly in many artificial (architectural)
        Message 3 of 23 , Feb 28, 2008
          I have been including a neutral "gray"("grey") target every time I
          shoot a panorama, for quite a while. Certainly in many artificial
          (architectural) situations it can be difficult to find a *true*
          neutral in the scene after the fact! (Whatever you click on with
          Photoshop's "neutral picker" produces a horrible result.)

          Aside: I consider it unfortunate that the term apparently has
          settled at "White Balance," when in fact it has to do with NEUTRAL
          balance. You might want to read
          Gray or White Card for Neutral Balancing?

          <http://rmimaging.com/information/gray_or_white.html>

          "Although the camera calls it 'white balance,' most cameras do not
          actually use a white card to perform this operation. Instead, they
          use a gray card, or a white card exposed so it appears gray. More
          properly white balance should be called neutral balance or, even
          better, light balance. What is actually happening is the balance
          between the color channels in the camera (red, green and blue,
          usually) are adjusted so a gray item will be imaged with equal RGB
          values under a given lighting."


          For my "neutral balance target" I currently use (yes) a WhiBal
          card. ;) Another nice one is the Digital Gray Card from Robin Myers
          Imaging <http://secure.netsolhost.com/664583.677720/Merchant2/
          merchant.mvc?Screen=CTGY&Store_Code=CI&Category_Code=GC>. Any
          "Photographic Grey Card" should work pretty well too.


          Addressing the original question, here's the way I currently work:

          I shoot in Raw. Although when using raw, the color temperature
          setting is not relevant, I still tend to set it to something that is
          close to what I consider the dominate lighting in my scene. (This
          just makes things easier when reviewing the images later.) I
          *always* include a neutral target in my first shot (the "slate"
          shot). [Yes, this means that my "4 shot" panorama actually requires
          FIVE shots; my 9 shot panorama requires 10 shots, etc.]


          Comment on Digital vs. Film: it seems to me that color difference
          between light sources are much less extreme using digital capture
          than when using film. Daylight compared to Tungsten is far less
          "electric blue"; Incandescent lamps are far less "candle-flame-red"
          when compared to daylight; Florescent lamps are not nearly so
          hideously green.


          I assume that even naive viewers implicitly realize that tungsten
          light tends to be redder, "North sky light" tends to be bluer [for
          those in the Southern Hemisphere, that would be "South sky light."
          Or perhaps we should say "Polar Direction Influenced Light. :) ]

          So... I tend to balance the color temperature of each pano toward
          what I consider the "dominant light" of the scene. A room lit by
          interior tungsten lights, having a "anti sun" window? Turn the dial
          until the window looks very blue and the interior only slightly red.

          Based on my believe the people (viewers) inherently understand that
          exterior light is likely to be bluer than interior light and that
          interior light is likely to be redder than exterior light, I just
          "turn the dial" until I feel the mixture is a plausible balance
          between interior and exterior light.

          I do NOT try to "neutralize" colors across all light sources. I feel
          that would look strange and feel unnatural. That is, "we know" that
          interior light is reddish. If you set the color balance of an
          interior light scene to dead neutral, it will look strange.


          By the way: a fabulous trick, apparently not well known: In
          Photoshop, open ANY file as if it were a Camera Raw file. This
          gives you access to all the Camera Raw controls, which *include*
          those nifty "Temperature" and "Tint" sliders.

          In Photoshop, choose File > Open... Navigate to the file you want
          to open. Select it (click on the name ONCE). Change the "Format:"
          pop-up to "Camera Raw" [NOT "Photoshop Raw... that's a totally
          different thing] and proceed.

          eo

          On Feb 28, 2008, at 7:38 PM, Georgia Real Tours wrote:

          > On 2/28/08, Nelson Mendes <nmendes@...> wrote:
          >>
          >> Hi, I work mainly with indoor panoramas, and what's been really a
          >> time
          >> consuming effort in the creation of the panoramas is the white
          >> balance
          >> compensation.
          >> The problem is that usually I have incandescent light inside and
          >> sun light
          >> on the outside, and that creates bluish tones (or redish tones
          >> depending on
          >> the white balance setting) on some areas of the panorama (like in
          >> open doors
          >> that lead to rooms with a great amount of outside light).
          >
          > Hi Nelson,
          >
          > I'm not sure exactly how to "mix" white balances under different
          > lighting conditions, but I do have a suggestion that might lead to
          > something useful. I just got a WhiBal set, and haven't yet had an
          > opportunity to test it out well enough. However, my idea was to
          > choose a single light source to do the rest of the pano's white
          > balance. In your case with a WhiBal, here's what I'd do: I'd shoot
          > the WhiBal under each light source. I'd then create a series of RAW
          > files optimized for each white balance. Once I did that, I'd create a
          > pano (strips, cubes, equi, etc.) for each optimized white balance.
          > After that, there's several different methods of combining them.
          >
          > All of that may sound like a lot of time-consuming work, but I don't
          > think it would be. You'd simply be shooting an extra shot for each
          > light source and making an equivalent number of RAW sets as are
          > light-source shots. And if you are using Bibble, you don't even have
          > to do that. Additionally, once you have the required CPs for one pano
          > you can batch stitch the rest.
          >
          > If you don't know what I WhiBal is (and I don't expect you to, I just
          > found out about it not long ago) it is a neutral color board whose
          > color value is known. You can find out more about it at
          > http://www.rawworkflow.com/products/whibal/index.html
          > <http://www.rawworkflow.com/products/whibal/index.html> While I
          > haven't yet tried it in a pano, it certainly has helped with regular
          > photos!
          >
          > Cheers,
          > Robert~
          > --
          > Mid GA: 478-599-1300
          > ATL: 678-438-6955
          > garealtours.com
          >
        • Rodolpho Pajuaba
          Instead of using RGB masks, the real solution is to look at the a and b channels after converting a copy to Lab. If the problem is in the yellow blue axis,
          Message 4 of 23 , Feb 29, 2008
            Instead of using RGB masks, the real solution is to look at the "a" and
            "b" channels after converting a copy to Lab. If the problem is in the
            yellow>blue axis, you´ll very likely be able to build a very accurate
            mask from the "b" channel, and apply it to a top, differently-corrected,
            layer. Not magic, it´s just a matter of knowing the available tools.
            Regards,
            Rodolpho Pajuaba

            Nelson Mendes escreveu:
            > Shawn, that's what I call "time consuming" task. It's more or less the
            > way I'm doing the corrections (I use Photo Filter Adjustment layers in
            > CS3 and mask the parts I don't need) but the masks sometimes are hard
            > to do without using transparency gradients or the edges will show up
            > on some areas where the WB is correct. I was wondering if anyone had a
            > different (magic??) approach to this :)
            >
            >


            [Non-text portions of this message have been removed]
          • Georgia Real Tours
            ... Wow, Eric! One of the most helpful and informative posts I ve read on this subject. :c) Cut-and-paste ready for the wiki, afaik. BTW, you re method of
            Message 5 of 23 , Feb 29, 2008
              On 2/29/08, Eric O'Brien <ericob@...> wrote:
              >
              > I have been including a neutral "gray"("grey") target every time I
              > shoot a panorama, for quite a while...

              Wow, Eric! One of the most helpful and informative posts I've read on
              this subject. :c) Cut-and-paste ready for the wiki, afaik.

              BTW, you're method of one extra shot in the pano with the neutral card
              is what I was envisioning. Nice to see I was headed down a working
              path. ;c)

              Thanks!

              Robert~

              --
              Mid GA: 478-599-1300
              ATL: 678-438-6955
              garealtours.com
            • panovrx
              ... Color correction is an area of active research and new technologies are emerging regularly -- so there are a plethora of thirdparty plugins for this some
              Message 6 of 23 , Feb 29, 2008
                --- In PanoToolsNG@yahoogroups.com, "Nelson Mendes" <nmendes@...> wrote:
                >
                > Hi, I work mainly with indoor panoramas, and what's been really a time
                > consuming effort in the creation of the panoramas is the white balance
                > compensation.
                >

                Color correction is an area of active research and new technologies are
                emerging regularly -- so there are a plethora of thirdparty plugins for
                this some of which are superior I think to anything in Photoshop. The
                recently announced Viveza plugin from Nik Efex looks particularly
                interesting ...
                http://www.niksoftware.com/viveza/en/entry.php?
                view=intro/viveza_announcement.shtml

                Peter
              • William Donelson
                I prepared a hardback 8x11 notebook (with 100 pages of lined note paper) for colour balance & correction: I went to a charity shop, and bought an old black
                Message 7 of 23 , Mar 1, 2008
                  I prepared a hardback 8x11 notebook (with 100 pages of lined note paper) for colour
                  balance & correction:

                  I went to a charity shop, and bought an old black velvet dress to cut up for patches.

                  I glued several pieces of the black velvet (with the "grain" in various directions) into the
                  front cover. Now, when the camera sees it, some of the patches look dark black, and
                  some look gray. The lined note paper looks white.

                  You can also arranged for the front cover to be "in the shade" (of itself or of some other
                  shadow) to get an even darker set of blacks.

                  This gives us a very good range of blacks, grays and whites to use in Photoshop
                  correction.

                  And, the notepaper can be used to mark down info about the shot.


                  Cheers
                  William



                  --- In PanoToolsNG@yahoogroups.com, Eric O'Brien <ericob@...> wrote:
                  >
                  > I have been including a neutral "gray"("grey") target every time I
                  > shoot a panorama, for quite a while. Certainly in many artificial
                  > (architectural) situations it can be difficult to find a *true*
                  > neutral in the scene after the fact! (Whatever you click on with
                  > Photoshop's "neutral picker" produces a horrible result.)
                  >
                • Snowy Aldon
                  Hi All, any colour balance work requires a spectrally neutral target to balance from. One which has little or no florescent materials. The targets that William
                  Message 8 of 23 , Mar 1, 2008
                    Hi All,

                    any colour balance work requires a spectrally neutral target to
                    balance from. One which has little or no florescent materials.

                    The targets that William has suggested would work well for tonal
                    adjustments but will almost certainly give colour casts under most
                    conditions.

                    >>
                    >> I prepared a hardback 8x11 notebook (with 100 pages of lined note
                    >> paper) for colour
                    >> balance & correction:
                    >>
                    >> I went to a charity shop, and bought an old black velvet dress to
                    >> cut up for patches.
                    >>
                    >> I glued several pieces of the black velvet (with the "grain" in
                    >> various directions) into the
                    >> front cover. Now, when the camera sees it, some of the patches
                    >> look dark black, and
                    >> some look gray. The lined note paper looks white



                    It is best to use a calibrated target like a macbeth chart or a QP card.

                    The placement of the target in the scene is very critical. In the
                    example being used of the room lit with tungsten balanced lighting
                    and also getting light from a window. the closer the neutral target
                    is placed to the lamp the more tungsten light and the bluer the
                    daylight and vice versa.

                    The same effect will be present in a landscape. If the target is
                    fully illuminated by the sun it will give a different result than in
                    the shade.

                    If you are on a lawn and the target is backlit so no sunlight is
                    falling on the target and it is shaded from the blue sky, a major
                    source of illumination will be bright green light from the lawn. If
                    this is then used to "neutralise" the images a magenta cast will
                    almost certainly be introduced.

                    In the case of VR Panoramas one must "correct" the image so that it
                    appears a faithful representation of the scene captured ( on a
                    profiled monitor). This of course forms an integral part of the
                    creative process. Relying on a mechanical approach to white balance
                    of digital will not give the best results. these targets and useful
                    guides when not used in the studio.

                    Hope this helps


                    best

                    Snowy





                    On 1 Mar 2008, at 13:33, William Donelson wrote:

                    > .
                    >
                    > You can also arranged for the front cover to be "in the shade" (of
                    > itself or of some other
                    > shadow) to get an even darker set of blacks.
                    >
                    > This gives us a very good range of blacks, grays and whites to use
                    > in Photoshop
                    > correction.
                    >
                    > And, the notepaper can be used to mark down info about the shot.
                    >
                    > Cheers
                    > William
                    >



                    [Non-text portions of this message have been removed]
                  • William Donelson
                    ... Yes, you do have to be careful, and aware of reflections and other light sources, as you mention. But the technique I outlined has given us the best
                    Message 9 of 23 , Mar 4, 2008
                      --- In PanoToolsNG@yahoogroups.com, Snowy Aldon <lists@...> wrote:
                      > The targets that William has suggested would work well for tonal
                      > adjustments but will almost certainly give colour casts under most
                      > conditions.
                      Yes, you do have to be careful, and aware of reflections and other light sources, as you
                      mention.

                      But the technique I outlined has given us the best results we've had in 15 years of doing
                      panoramas.

                      Properly used, it never gives colour casts, or false colours, except in extreme circumstances.

                      We tried using colour charts and grayscale charts, but these were essentially useless, as they
                      are far too dependent on the lighting conditions.

                      The "best black" can be achieved by building a box, lined with black velvet, and open on
                      one side, so that the interior is completely unlit. But, we have found this to be unnecessary,
                      except in unusual circumstances.
                    • Snowy Aldon
                      Hi, I m really interested in this technique. The comments we re made as an extrapolation of colour management in the studio and on location. I have been using
                      Message 10 of 23 , Mar 4, 2008
                        Hi,

                        I'm really interested in this technique.

                        The comments we're made as an extrapolation of colour management in
                        the studio and on location. I have been using various method and
                        targets with some success.

                        It seems strange that the velvet gives a neutral value when
                        illuminated to be in the mid-tone. I would have have supposed that
                        the colour bias of the dyes would become apparent and introduce a cast.

                        Do you colour balance/correct/neutralise to the velvet and adjust the
                        images to give an equal RGB value grey? And how does achieving a
                        truly "black" black give any information regarding the colour balance
                        of the image?

                        TIA

                        Snowy

                        On 4 Mar 2008, at 14:53, William Donelson wrote:



                        >> --- In PanoToolsNG@yahoogroups.com, Snowy Aldon <lists@...> wrote:
                        >> > The targets that William has suggested would work well for tonal
                        >> > adjustments but will almost certainly give colour casts under most
                        >> > conditions.
                        >> Yes, you do have to be careful, and aware of reflections and other
                        >> light sources, as you
                        >> mention.
                        >>
                        >> But the technique I outlined has given us the best results we've
                        >> had in 15 years of doing
                        >> panoramas.
                        >>
                        >> Properly used, it never gives colour casts, or false colours,
                        >> except in extreme circumstances.
                        >>
                        >> We tried using colour charts and grayscale charts, but these were
                        >> essentially useless, as they
                        >> are far too dependent on the lighting conditions.
                        >>
                        >> The "best black" can be achieved by building a box, lined with
                        >> black velvet, and open on
                        >> one side, so that the interior is completely unlit. But, we have
                        >> found this to be unnecessary,
                        >> except in unusual circumstances.
                        >


                        [Non-text portions of this message have been removed]
                      • William Donelson
                        ... You have to be careful which patch of velvet you use. Some are not black. ... We do not use the box-of-velvet anymore, as our 4 patches of velvet at
                        Message 11 of 23 , Mar 4, 2008
                          --- In PanoToolsNG@yahoogroups.com, Snowy Aldon <lists@...> wrote:
                          > It seems strange that the velvet gives a neutral value when
                          > illuminated to be in the mid-tone. I would have have supposed that
                          > the colour bias of the dyes would become apparent and introduce a cast.

                          You have to be careful which patch of velvet you use. Some are not black.

                          > Do you colour balance/correct/neutralise to the velvet and adjust the
                          > images to give an equal RGB value grey? And how does achieving a
                          > truly "black" black give any information regarding the colour balance
                          > of the image?

                          We do not use the box-of-velvet anymore, as our "4 patches of velvet" at different
                          orientations works very well. Some of the patches look blacker than others, and some can
                          be used as gray-level samples.

                          Having an in-scene black is useful if you are shooting on film (as we usually do - Seitz
                          Super Roundshot 220).

                          Having specular (over-exposed) white patches are not useful, so we use a variety of
                          techniques in Photoshop to set the top white level.

                          In the end, the velvet-patches are a short-cut to getting NEAR to correct colour, and we
                          use Photoshop to adjust the colour to "Correct" levels by eye and memory.

                          Hope this helps.
                        • Rik Littlefield
                          ... Using black velvet this way is a very clever trick. What happens, I believe, is that the gray appearance is caused by a myriad of specular reflections
                          Message 12 of 23 , Mar 4, 2008
                            --- In PanoToolsNG@yahoogroups.com, "William Donelson" <wd@...> wrote:
                            >
                            > --- In PanoToolsNG@yahoogroups.com, Snowy Aldon <lists@> wrote:
                            > > It seems strange that the velvet gives a neutral value when
                            > > illuminated to be in the mid-tone. I would have have supposed
                            > > that the colour bias of the dyes would become apparent
                            > > and introduce a cast.
                            >
                            > You have to be careful which patch of velvet you use.
                            > Some are not black.
                            >
                            > > Do you colour balance/correct/neutralise to the velvet
                            > > and adjust the images to give an equal RGB value grey?
                            > > And how does achieving a truly "black" black give any
                            > > information regarding the colour balance
                            > > of the image?
                            >
                            > We do not use the box-of-velvet anymore, as our
                            > "4 patches of velvet" at different orientations
                            > works very well. Some of the patches look blacker
                            > than others, and some can be used as gray-level samples.

                            Using black velvet this way is a very clever trick. What happens, I
                            believe, is that the "gray" appearance is caused by a myriad of
                            specular reflections from the surfaces of the fibers. Specular
                            reflections are always non-colored, so indeed this method should
                            produce a very neutral gray as long as the body of the fibers is very
                            dark in comparison.

                            --Rik
                          • johncharlesriley
                            ... Sorry, I have to jump in here. I am not sure what you might be thinking of, but specular reflections have the same color as the incident light. When you
                            Message 13 of 23 , Mar 7, 2008
                              >
                              > Using black velvet this way is a very clever trick. What happens, I
                              > believe, is that the "gray" appearance is caused by a myriad of
                              > specular reflections from the surfaces of the fibers. Specular
                              > reflections are always non-colored, so indeed this method should
                              > produce a very neutral gray as long as the body of the fibers is very
                              > dark in comparison.
                              >
                              > --Rik
                              >

                              Sorry, I have to jump in here. I am not sure what you might be thinking of, but specular
                              reflections have the same color as the incident light. When you see yourself in a mirror,
                              that is a specular reflection. A specular reflection is simply when light is reflected in a
                              mirror-like fashion from a smooth surface. Examples are the glare off of a car (or water
                              or snow) from the sun. They are problematic because you are seeing a reflection of the
                              sun and not the object itself. Since specular reflections are partially polarized (or
                              completely if at Brewster's angle), polarized sunglasses can drastically reduce their
                              intensity. Then you can see the object itself by the diffusely reflected light, which is
                              scattered in all directions.

                              Sorry for being pedantic, but I am a physics professor and just can't help it 8-) Now, what
                              else might be going on with the fibers of black velvet, I don't know, but it could be
                              interesting to hear.

                              John
                            • Georgia Real Tours
                              ... Exactly. The grain of the fabric acts as a rudimentary polarization filter. Further, since it is diffuse, the light reflected is a culmination of the
                              Message 14 of 23 , Mar 8, 2008
                                On 3/7/08, johncharlesriley <johnriley@...> wrote:
                                > >
                                > > Using black velvet this way is a very clever trick. What happens, I
                                > > believe, is that the "gray" appearance is caused by a myriad of
                                > > specular reflections from the surfaces of the fibers. Specular
                                > > reflections are always non-colored, so indeed this method should
                                > > produce a very neutral gray as long as the body of the fibers is very
                                > > dark in comparison.
                                > >
                                > > --Rik
                                > >
                                >
                                > Sorry, I have to jump in here. I am not sure what you might be thinking of, but specular
                                > reflections have the same color as the incident light. When you see yourself in a mirror,
                                > that is a specular reflection. A specular reflection is simply when light is reflected in a
                                > mirror-like fashion from a smooth surface. Examples are the glare off of a car (or water
                                > or snow) from the sun. They are problematic because you are seeing a reflection of the
                                > sun and not the object itself. Since specular reflections are partially polarized (or
                                > completely if at Brewster's angle), polarized sunglasses can drastically reduce their
                                > intensity. Then you can see the object itself by the diffusely reflected light, which is
                                > scattered in all directions.
                                >
                                > Sorry for being pedantic, but I am a physics professor and just can't help it 8-) Now, what
                                > else might be going on with the fibers of black velvet, I don't know, but it could be
                                > interesting to hear.

                                Exactly. The grain of the fabric acts as a rudimentary polarization
                                filter. Further, since it is diffuse, the light reflected is a
                                culmination of the ambient light in the room. The average of all
                                those random specular reflections is what is sought.

                                But you knew that and were just testing us! Very tricky, Mr. Riley,
                                but it's turtles all the way down!

                                ;c)

                                R~


                                --
                                Mid GA: 478-599-1300
                                ATL: 678-438-6955
                                garealtours.com
                              • Ken Warner
                                I get that :-) Georgia Real Tours wrote: [stuff deleted] Very tricky, Mr. Riley, but it s turtles all the way down!
                                Message 15 of 23 , Mar 8, 2008
                                  I get that :-)

                                  Georgia Real Tours wrote:
                                  [stuff deleted]

                                  Very tricky, Mr. Riley, but it's turtles all the way down!
                                • Rik Littlefield
                                  ... Yes, exactly. Previous writers were concerned about the color of the fibers producing something other than a non-neutral gray. When I wrote that the
                                  Message 16 of 23 , Mar 8, 2008
                                    --- In PanoToolsNG@yahoogroups.com, "johncharlesriley"
                                    <johnriley@...> wrote:
                                    >
                                    > >
                                    > > Using black velvet this way is a very clever trick.
                                    > > What happens, I believe, is that the "gray" appearance
                                    > > is caused by a myriad of specular reflections
                                    > > from the surfaces of the fibers. Specular
                                    > > reflections are always non-colored, so indeed
                                    > > this method should produce a very neutral gray
                                    > > as long as the body of the fibers is very
                                    > > dark in comparison.
                                    > >
                                    > > --Rik
                                    > >
                                    >
                                    > Sorry, I have to jump in here. I am not sure what
                                    > you might be thinking of, but specular reflections
                                    > have the same color as the incident light.

                                    Yes, exactly. Previous writers were concerned about the color of the
                                    fibers producing something other than a non-neutral gray. When I
                                    wrote that the reflection was "non-colored", what I meant was that
                                    the color of the reflected light would not be altered by the color of
                                    the underlying fiber, so the myriad of specular reflections taken
                                    together would act like a neutral gray diffuse reflector. Sorry I
                                    did not use enough words to make that completely clear.

                                    --Rik
                                  • Georgia Real Tours
                                    ... Oops, my bad. You used enough words; I just failed to use all of them. Kinda makes a difference when you get em all rounded up. :c R~ -- Mid GA:
                                    Message 17 of 23 , Mar 10, 2008
                                      On 3/9/08, Rik Littlefield <rj.littlefield@...> wrote:
                                      >
                                      > --- In PanoToolsNG@yahoogroups.com, "johncharlesriley"
                                      > <johnriley@...> wrote:
                                      > >
                                      > > >
                                      > > > Using black velvet this way is a very clever trick.
                                      > > > What happens, I believe, is that the "gray" appearance
                                      > > > is caused by a myriad of specular reflections
                                      > > > from the surfaces of the fibers. Specular
                                      > > > reflections are always non-colored, so indeed
                                      > > > this method should produce a very neutral gray
                                      > > > as long as the body of the fibers is very
                                      > > > dark in comparison.
                                      > > >
                                      > > > --Rik
                                      > > >
                                      > >
                                      > > Sorry, I have to jump in here. I am not sure what
                                      > > you might be thinking of, but specular reflections
                                      > > have the same color as the incident light.
                                      >

                                      > together would act like a neutral gray diffuse reflector. Sorry I
                                      > did not use enough words to make that completely clear.


                                      Oops, my bad. You used enough words; I just failed to use all of
                                      them. Kinda makes a difference when you get 'em all rounded up. :c\

                                      R~


                                      --
                                      Mid GA: 478-599-1300
                                      ATL: 678-438-6955
                                      garealtours.com
                                    • Luca Vascon
                                      I simply use a white plastic drinking cup. One of those very cheap ones you buy at supermarket. I put it in front of the lens with transparent tape. I shoot
                                      Message 18 of 23 , Mar 10, 2008
                                        I simply use a white plastic drinking cup.
                                        One of those very cheap ones you buy at supermarket.
                                        I put it in front of the lens with transparent tape.
                                        I shoot one picture against main lightsource, completely out of focus.
                                        Like it was taking incident light.
                                        I make white on that.
                                        Those things are made of a plastic whose physical propreiety is also to
                                        be... perfectly white.
                                        If you fisheye-shoot one from inside you have a kind of light dome of
                                        all light sources and principal chrominance of light reflection.
                                        You don't need anything else.

                                        Georgia Real Tours ha scritto:
                                        >
                                        > On 3/9/08, Rik Littlefield <rj.littlefield@...
                                        > <mailto:rj.littlefield%40computer.org>> wrote:
                                        > >
                                        > > --- In PanoToolsNG@yahoogroups.com
                                        > <mailto:PanoToolsNG%40yahoogroups.com>, "johncharlesriley"
                                        > > <johnriley@...> wrote:
                                        > > >
                                        > > > >
                                        > > > > Using black velvet this way is a very clever trick.
                                        > > > > What happens, I believe, is that the "gray" appearance
                                        > > > > is caused by a myriad of specular reflections
                                        > > > > from the surfaces of the fibers. Specular
                                        > > > > reflections are always non-colored, so indeed
                                        > > > > this method should produce a very neutral gray
                                        > > > > as long as the body of the fibers is very
                                        > > > > dark in comparison.
                                        > > > >
                                        > > > > --Rik
                                        > > > >
                                        > > >
                                        > > > Sorry, I have to jump in here. I am not sure what
                                        > > > you might be thinking of, but specular reflections
                                        > > > have the same color as the incident light.
                                        > >
                                        >
                                        > > together would act like a neutral gray diffuse reflector. Sorry I
                                        > > did not use enough words to make that completely clear.
                                        >
                                        > Oops, my bad. You used enough words; I just failed to use all of
                                        > them. Kinda makes a difference when you get 'em all rounded up. :c\
                                        >
                                        > R~
                                        >
                                        > --
                                        > Mid GA: 478-599-1300
                                        > ATL: 678-438-6955
                                        > garealtours.com
                                        >
                                        >
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