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Re: [PanoToolsNG] Re: ProPhoto RGB Color Space - Perhaps an irrelevant question

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  • Mr. Roger Howard
    ... Why are you picking ProPhoto to begin with? Have you done any testing that shows you a benefit of working in this space? In any case... let s assume you ve
    Message 1 of 8 , Aug 1, 2006
      On Aug 1, 2006, at 6:12 PM, LoveFilm wrote:

      > I just realized there might be no benefit to inputting ProPhoto RGB
      > images into the panoramic chain - since I don't really do any editing
      > to the source materials till after they are stitched (in which case I
      > could always converted to that color space if necessary).

      Why are you picking ProPhoto to begin with? Have you done any testing
      that shows you a benefit of working in this space? In any case...
      let's assume you've selected ProPhoto for a reason. Then it would
      make *no* sense to use a smaller gamut space first, and then convert
      to ProPhoto. ProPhoto, if you have a reason to use it, should always
      be used before smaller gamut spaces in your process, not after, or
      it's lost any value it might have.

      > Or would the larger color space - if supported - provide some benefit
      > to guard against things like banding in the sky, as working in 16bit
      > does ???

      Actually quite the opposite. The simplest explanation is this:

      In digital images the tonal scale, from white to black, is cut up
      into a fixed number of tones. In a wider gamut space, that number of
      tones has to cover a *wider* range than in a smaller space, therefore
      the steps in between each tone are larger, and any loss of tones
      because of compression/expansion will be more obvious. Therefore
      larger gamut spaces tend to show banding sooner.

      In fact the ongoing, multi-year debate on a few other mailing lists
      about 8 vs 16 bits has only been able to really agree on a single
      point - that 16bit CAN be useful when working in wide gamut spaces
      like ProPhoto. So at least if you're going to use ProPhoto, you
      should use 16bit.

      But my advice is to work in sRGB until you understand all of this, or
      at most work in Adobe RGB. Test as much as possible and see if you
      can find any real situation where the wider gamut space makes any
      difference in the quality of your work - I'll bet it won't, or it may
      actually have a negative impact.

      -R
    • LoveFilm
      ... testing that shows you a benefit of working in this space? I have been using ProPhoto for a little over a year now - Mostly for my Product Shots, since
      Message 2 of 8 , Aug 1, 2006
        --- In PanoToolsNG@yahoogroups.com, "Mr. Roger Howard"
        <rogerhoward@...> wrote:
        >
        >
        > Why are you picking ProPhoto to begin with? Have you done any
        testing that shows you a benefit of working in this space?

        I have been using ProPhoto for a little over a year now - Mostly for
        my Product Shots, since these images are frequently being used for
        mult-purposes, such as on the web and for print. It is my
        understanding that ProPhoto is an excellent 'storage' color space,
        from which one file can then easily be converted to other spaces
        according to indented output.

        Until just now, I hadn't really considered it for pano creation and I
        guess the only benefit would be to maintain a consistent work flow
        with all my other photos.


        if you have a reason to use it, should always
        > be used before smaller gamut spaces in your process, not after, or
        > it's lost any value it might have.

        Thanks, you confirmed what I initiallly suspected.


        >
        > In fact the ongoing, multi-year debate on a few other mailing lists
        > about 8 vs 16 bits has only been able to really agree on a single
        > point - that 16bit CAN be useful when working in wide gamut spaces
        > like ProPhoto. So at least if you're going to use ProPhoto, you
        > should use 16bit.

        I do always use it w/ 16 bit. Regarding some of the other forums,
        here is a current thread on Kekus regarding 'color degration' that
        might be of interest.

        http://www.kekus.com/forum/showthread.php?t=1429
      • JD Smith
        ... Hugin v0.6 also copies input ICC profiles to the output.
        Message 3 of 8 , Aug 2, 2006
          On Tue, 01 Aug 2006 18:11:21 -0700, Mr. Roger Howard wrote:

          > All the tools you mention are essentially color management-ignorant, so
          > the short answer is "yes". None of these tools will do any color space
          > conversion, so the colors you feed in come out untouched. The catch is
          > that most tools do not copy the source document's ICC profile into the
          > output, so your output files are untagged (but, crucially, still in the
          > same color space). PTGUI I believe is properly bringing source profiles
          > over now. In any case, you can work in any RGB space you want, but you'll
          > likely need to retag the output with the same space as your input.

          Hugin v0.6 also copies input ICC profiles to the output.
        • Roger Howard
          ... Yay! Now how about copying EXIF/XMP/IPTC? You could integrate ExifTool from Phil Harvey for this. Or even better, how about a standard way to run a
          Message 4 of 8 , Aug 2, 2006
            On Wed, August 2, 2006 9:23 am, JD Smith wrote:
            > On Tue, 01 Aug 2006 18:11:21 -0700, Mr. Roger Howard wrote:
            >
            >> All the tools you mention are essentially color management-ignorant, so
            >> the short answer is "yes". None of these tools will do any color space
            >> conversion, so the colors you feed in come out untouched. The catch is
            >> that most tools do not copy the source document's ICC profile into the
            >> output, so your output files are untagged (but, crucially, still in the
            >> same color space). PTGUI I believe is properly bringing source profiles
            >> over now. In any case, you can work in any RGB space you want, but
            >> you'll
            >> likely need to retag the output with the same space as your input.
            >
            > Hugin v0.6 also copies input ICC profiles to the output.

            Yay!

            Now how about copying EXIF/XMP/IPTC? You could integrate ExifTool from
            Phil Harvey for this.

            Or even better, how about a standard way to run a post-render script so I
            can do it myself if needed? This way we could attach a script to each
            render process that will get fired off at the end, ideally with the paths
            to source and output images (or just the whole PTO script) passed to the
            post-script.

            I do this with a hotfolder now, but it's a bit tricky to get timing right
            in all cases. I'd rather do it explicitly this way than have a script have
            to poll for the status of an output files file locks.

            -R
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