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Re: [kakadu_jpeg2000] Re: Kakadu 5.2.2: Layers, Levels, Reversible

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  • David Taubman
    Hi John, If you don t set the rate explicitly, the final layer will be numerically lossless. The bit-rates of the other layers will be automatically deduced
    Message 1 of 8 , Dec 20, 2006
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      Hi John,

      If you don't set the rate explicitly, the final layer will be numerically
      lossless. The bit-rates of the other layers will be automatically
      deduced from that of the final (lossless) layer, via the logarithmic
      spacing approach I mentioned. If you specify the bit-rates explicitly,
      you must be sure to specify a "-" for the last quality layer, rather than
      just a very high bit-rate, if you want truly lossless.

      Cheers,

      David

      ----- Original Message -----
      From: "novakjohnj" <john.j.novak@...>
      To: <kakadu_jpeg2000@yahoogroups.com>
      Sent: Thursday, December 21, 2006 12:29 AM
      Subject: [kakadu_jpeg2000] Re: Kakadu 5.2.2: Layers, Levels, Reversible


      >
      > Hi,
      >
      > Yes, that's what I observed during my testing. I have a
      > specification that requires the compressed image to be visually
      > lossless at 18 layers and numerically lossless at 19. The last can
      > be handled simply by setting Creversible=yes. However, if I don't
      > set the flag (default is no) what is the default rate? Can I expect
      > a visually lossless image when I get to layer 18?
      >
      > Thanks, John
      >
      > --- In kakadu_jpeg2000@yahoogroups.com, "jratike80"
      > <jukka.rahkonen@...> wrote:
      >>
      >> Hi,
      >>
      >> Number of quality layers does not have any effect on the final
      > quality
      >> of compression. That it determined by the -rate parameter.
      > Number of
      >> quality layers is just telling how many more compressed versions of
      >> the image are calculated inside the codestream.
      >>
      >> The only way to achieve a real lossless compression is to use
      >> 'Creversible=yes' argument. If that is set you will get a lossless
      >> compression even with just one quality layer. If fact having just
      > one
      >> quality layer seems to be more common than having quite a many as
      >> instructed in Kakadu examples. For example ER Mapper jpeg2000
      >> compressor defaults to having one quality layer.
      >>
      >> Advantage in having many quality layers is that is enables quality
      >> progressive browsing, so with just minor part of the codestream
      > read
      >> you can see the image, first with poor quality that is getting
      > better
      >> and better while you receive more data (quality layers) from the
      >> codestream. Not many image browsers have support for this kind of
      >> quality progressive reading. Kdu_show is one of them. If browser
      >> does not support quolity progressive reading then I believe that
      >> having many quality layers in the jpeg2000 image does not give any
      >> advantage for the user.
      >>
      >> If you consider using JPIP protocol some day for serving jpeg2000
      >> images quality layers would be nice to have. For local use it is
      > not
      >> so necessary.
      >>
      >> Regards
      >>
      >> -Jukka Rahkonen-
      >>
      >>
      >>
      >> --- In kakadu_jpeg2000@yahoogroups.com, "novakjohnj"
      >> <john.j.novak@> wrote:
      >> >
      >> > I've seen references to using 19 (visually lossless) and 20
      >> > (numerically lossless) layers during compression. With Kakadu,
      > I
      >> > still need to set 'Creversible=yes' to obtain a numerically
      > lossless
      >> > compressed image. I've noticed that with that option set, I can
      >> > achieve numerically lossless compression with a lower layers
      > count.
      >> > How do these parameters relate to each other in the compressor?
      > Is
      >> > there a recommendation on when 'Creversible=yes' should be used?
      >> >
      >> > Thanks, John
      >> >
      >>
      >
      >
      >
      >
      > For problems with your subscription in this group please email
      > kakadu_jpeg2000-owner@yahoogroups.com.
      >
      > Yahoo! Groups Links
      >
      >
      >
      >
    • novakjohnj
      Hi David, Your explanation is useful. However, I cannot figure out how to specify the bit-rates to the compressor for each layer in the core SDK. I am not
      Message 2 of 8 , Dec 21, 2006
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        Hi David,

        Your explanation is useful. However, I cannot figure out how to
        specify the bit-rates to the compressor for each layer in the core
        SDK. I am not using the kdu_compress application.

        Thanks, John

        --- In kakadu_jpeg2000@yahoogroups.com, "David Taubman"
        <d.taubman@...> wrote:
        >
        > Hi John,
        >
        > If you don't set the rate explicitly, the final layer will be
        numerically
        > lossless. The bit-rates of the other layers will be automatically
        > deduced from that of the final (lossless) layer, via the
        logarithmic
        > spacing approach I mentioned. If you specify the bit-rates
        explicitly,
        > you must be sure to specify a "-" for the last quality layer,
        rather than
        > just a very high bit-rate, if you want truly lossless.
        >
        > Cheers,
        >
        > David
        >
        > ----- Original Message -----
        > From: "novakjohnj" <john.j.novak@...>
        > To: <kakadu_jpeg2000@yahoogroups.com>
        > Sent: Thursday, December 21, 2006 12:29 AM
        > Subject: [kakadu_jpeg2000] Re: Kakadu 5.2.2: Layers, Levels,
        Reversible
        >
        >
        > >
        > > Hi,
        > >
        > > Yes, that's what I observed during my testing. I have a
        > > specification that requires the compressed image to be visually
        > > lossless at 18 layers and numerically lossless at 19. The last
        can
        > > be handled simply by setting Creversible=yes. However, if I
        don't
        > > set the flag (default is no) what is the default rate? Can I
        expect
        > > a visually lossless image when I get to layer 18?
        > >
        > > Thanks, John
        > >
        > > --- In kakadu_jpeg2000@yahoogroups.com, "jratike80"
        > > <jukka.rahkonen@> wrote:
        > >>
        > >> Hi,
        > >>
        > >> Number of quality layers does not have any effect on the final
        > > quality
        > >> of compression. That it determined by the -rate parameter.
        > > Number of
        > >> quality layers is just telling how many more compressed
        versions of
        > >> the image are calculated inside the codestream.
        > >>
        > >> The only way to achieve a real lossless compression is to use
        > >> 'Creversible=yes' argument. If that is set you will get a
        lossless
        > >> compression even with just one quality layer. If fact having
        just
        > > one
        > >> quality layer seems to be more common than having quite a many
        as
        > >> instructed in Kakadu examples. For example ER Mapper jpeg2000
        > >> compressor defaults to having one quality layer.
        > >>
        > >> Advantage in having many quality layers is that is enables
        quality
        > >> progressive browsing, so with just minor part of the codestream
        > > read
        > >> you can see the image, first with poor quality that is getting
        > > better
        > >> and better while you receive more data (quality layers) from the
        > >> codestream. Not many image browsers have support for this kind
        of
        > >> quality progressive reading. Kdu_show is one of them. If
        browser
        > >> does not support quolity progressive reading then I believe that
        > >> having many quality layers in the jpeg2000 image does not give
        any
        > >> advantage for the user.
        > >>
        > >> If you consider using JPIP protocol some day for serving
        jpeg2000
        > >> images quality layers would be nice to have. For local use it
        is
        > > not
        > >> so necessary.
        > >>
        > >> Regards
        > >>
        > >> -Jukka Rahkonen-
        > >>
        > >>
        > >>
        > >> --- In kakadu_jpeg2000@yahoogroups.com, "novakjohnj"
        > >> <john.j.novak@> wrote:
        > >> >
        > >> > I've seen references to using 19 (visually lossless) and 20
        > >> > (numerically lossless) layers during compression. With
        Kakadu,
        > > I
        > >> > still need to set 'Creversible=yes' to obtain a numerically
        > > lossless
        > >> > compressed image. I've noticed that with that option set, I
        can
        > >> > achieve numerically lossless compression with a lower layers
        > > count.
        > >> > How do these parameters relate to each other in the
        compressor?
        > > Is
        > >> > there a recommendation on when 'Creversible=yes' should be
        used?
        > >> >
        > >> > Thanks, John
        > >> >
        > >>
        > >
        > >
        > >
        > >
        > > For problems with your subscription in this group please email
        > > kakadu_jpeg2000-owner@yahoogroups.com
        > >
        > > Yahoo! Groups Links
        > >
        > >
        > >
        > >
        >
      • David Taubman
        HI John, No problem. This is done via the `kdu_codestream::flush function. Amongst other things, this function accepts an array of lengths (measured in
        Message 3 of 8 , Dec 21, 2006
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          HI John,

          No problem. This is done via the `kdu_codestream::flush' function.
          Amongst other things, this function accepts an array of lengths
          (measured in bytes) for each quality layer. Actually, each length
          corresponds to the total number of bytes in that layer and all
          previous layers. If you leave an entry equal to 0, the relevant length
          is calculated using the logarithmic progression I mentioned. If
          you leave the last entry 0, the final layer will be lossless. The
          function can also be driven directly by a collection of supplied
          distortion-length slope thresholds for each layer, or else it can
          be driven by the lengths and return the slopes. For more on all
          this, look at the documentation of the `kdu_codestream::flush' function
          (I suggest you ignore the material on incremental flushing for the
          time being, since that is more complex).

          If you are using `kdu_stripe_compressor' as a higher level
          compression engine, you do not call `kdu_codestream::flush'
          directly, but you pass the same parameters into the `start'
          function -- these are all optional arguments, so read the function
          descriptions.

          Cheers,

          David


          ----- Original Message -----
          From: "novakjohnj" <john.j.novak@...>
          To: <kakadu_jpeg2000@yahoogroups.com>
          Sent: Friday, December 22, 2006 5:48 AM
          Subject: [kakadu_jpeg2000] Re: Kakadu 5.2.2: Layers, Levels, Reversible


          > Hi David,
          >
          > Your explanation is useful. However, I cannot figure out how to
          > specify the bit-rates to the compressor for each layer in the core
          > SDK. I am not using the kdu_compress application.
          >
          > Thanks, John
          >
          > --- In kakadu_jpeg2000@yahoogroups.com, "David Taubman"
          > <d.taubman@...> wrote:
          >>
          >> Hi John,
          >>
          >> If you don't set the rate explicitly, the final layer will be
          > numerically
          >> lossless. The bit-rates of the other layers will be automatically
          >> deduced from that of the final (lossless) layer, via the
          > logarithmic
          >> spacing approach I mentioned. If you specify the bit-rates
          > explicitly,
          >> you must be sure to specify a "-" for the last quality layer,
          > rather than
          >> just a very high bit-rate, if you want truly lossless.
          >>
          >> Cheers,
          >>
          >> David
          >>
          >> ----- Original Message -----
          >> From: "novakjohnj" <john.j.novak@...>
          >> To: <kakadu_jpeg2000@yahoogroups.com>
          >> Sent: Thursday, December 21, 2006 12:29 AM
          >> Subject: [kakadu_jpeg2000] Re: Kakadu 5.2.2: Layers, Levels,
          > Reversible
          >>
          >>
          >> >
          >> > Hi,
          >> >
          >> > Yes, that's what I observed during my testing. I have a
          >> > specification that requires the compressed image to be visually
          >> > lossless at 18 layers and numerically lossless at 19. The last
          > can
          >> > be handled simply by setting Creversible=yes. However, if I
          > don't
          >> > set the flag (default is no) what is the default rate? Can I
          > expect
          >> > a visually lossless image when I get to layer 18?
          >> >
          >> > Thanks, John
          >> >
          >> > --- In kakadu_jpeg2000@yahoogroups.com, "jratike80"
          >> > <jukka.rahkonen@> wrote:
          >> >>
          >> >> Hi,
          >> >>
          >> >> Number of quality layers does not have any effect on the final
          >> > quality
          >> >> of compression. That it determined by the -rate parameter.
          >> > Number of
          >> >> quality layers is just telling how many more compressed
          > versions of
          >> >> the image are calculated inside the codestream.
          >> >>
          >> >> The only way to achieve a real lossless compression is to use
          >> >> 'Creversible=yes' argument. If that is set you will get a
          > lossless
          >> >> compression even with just one quality layer. If fact having
          > just
          >> > one
          >> >> quality layer seems to be more common than having quite a many
          > as
          >> >> instructed in Kakadu examples. For example ER Mapper jpeg2000
          >> >> compressor defaults to having one quality layer.
          >> >>
          >> >> Advantage in having many quality layers is that is enables
          > quality
          >> >> progressive browsing, so with just minor part of the codestream
          >> > read
          >> >> you can see the image, first with poor quality that is getting
          >> > better
          >> >> and better while you receive more data (quality layers) from the
          >> >> codestream. Not many image browsers have support for this kind
          > of
          >> >> quality progressive reading. Kdu_show is one of them. If
          > browser
          >> >> does not support quolity progressive reading then I believe that
          >> >> having many quality layers in the jpeg2000 image does not give
          > any
          >> >> advantage for the user.
          >> >>
          >> >> If you consider using JPIP protocol some day for serving
          > jpeg2000
          >> >> images quality layers would be nice to have. For local use it
          > is
          >> > not
          >> >> so necessary.
          >> >>
          >> >> Regards
          >> >>
          >> >> -Jukka Rahkonen-
          >> >>
          >> >>
          >> >>
          >> >> --- In kakadu_jpeg2000@yahoogroups.com, "novakjohnj"
          >> >> <john.j.novak@> wrote:
          >> >> >
          >> >> > I've seen references to using 19 (visually lossless) and 20
          >> >> > (numerically lossless) layers during compression. With
          > Kakadu,
          >> > I
          >> >> > still need to set 'Creversible=yes' to obtain a numerically
          >> > lossless
          >> >> > compressed image. I've noticed that with that option set, I
          > can
          >> >> > achieve numerically lossless compression with a lower layers
          >> > count.
          >> >> > How do these parameters relate to each other in the
          > compressor?
          >> > Is
          >> >> > there a recommendation on when 'Creversible=yes' should be
          > used?
          >> >> >
          >> >> > Thanks, John
          >> >> >
          >> >>
          >> >
          >> >
          >> >
          >> >
          >> > For problems with your subscription in this group please email
          >> > kakadu_jpeg2000-owner@yahoogroups.com
          >> >
          >> > Yahoo! Groups Links
          >> >
          >> >
          >> >
          >> >
          >>
          >
          >
          >
          >
          > For problems with your subscription in this group please email
          > kakadu_jpeg2000-owner@yahoogroups.com.
          >
          > Yahoo! Groups Links
          >
          >
          >
          >
        • novakjohnj
          Hi David, Okay, I ve looked at this but I still need some advice (i.e., help). My requirements are Layer 0: 0.03125 bpppb, Layer 1: 0.0625 bpppb, Layer 2:
          Message 4 of 8 , Jan 10, 2007
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            Hi David,

            Okay, I've looked at this but I still need some advice (i.e.,
            help). My requirements are Layer 0: 0.03125 bpppb, Layer 1: 0.0625
            bpppb, Layer 2: 0.125 bpppb, ..., Layer 18: 3.5 bpppb, Layer 19:
            Numerically Lossless. 'bpppb' is bits per pixel per band. Layer 18
            is Visually Lossless. How do I translate the 'bpppb' values into
            bytes or can these values be passed directly to Kakadu?

            Thanks, John

            --- In kakadu_jpeg2000@yahoogroups.com, "David Taubman"
            <d.taubman@...> wrote:
            >
            > HI John,
            >
            > No problem. This is done via the `kdu_codestream::flush' function.
            > Amongst other things, this function accepts an array of lengths
            > (measured in bytes) for each quality layer. Actually, each length
            > corresponds to the total number of bytes in that layer and all
            > previous layers. If you leave an entry equal to 0, the relevant
            length
            > is calculated using the logarithmic progression I mentioned. If
            > you leave the last entry 0, the final layer will be lossless. The
            > function can also be driven directly by a collection of supplied
            > distortion-length slope thresholds for each layer, or else it can
            > be driven by the lengths and return the slopes. For more on all
            > this, look at the documentation of the `kdu_codestream::flush'
            function
            > (I suggest you ignore the material on incremental flushing for the
            > time being, since that is more complex).
            >
            > If you are using `kdu_stripe_compressor' as a higher level
            > compression engine, you do not call `kdu_codestream::flush'
            > directly, but you pass the same parameters into the `start'
            > function -- these are all optional arguments, so read the function
            > descriptions.
            >
            > Cheers,
            >
            > David
            >
            >
            > ----- Original Message -----
            > From: "novakjohnj" <john.j.novak@...>
            > To: <kakadu_jpeg2000@yahoogroups.com>
            > Sent: Friday, December 22, 2006 5:48 AM
            > Subject: [kakadu_jpeg2000] Re: Kakadu 5.2.2: Layers, Levels,
            Reversible
            >
            >
            > > Hi David,
            > >
            > > Your explanation is useful. However, I cannot figure out how to
            > > specify the bit-rates to the compressor for each layer in the
            core
            > > SDK. I am not using the kdu_compress application.
            > >
            > > Thanks, John
            > >
            > > --- In kakadu_jpeg2000@yahoogroups.com, "David Taubman"
            > > <d.taubman@> wrote:
            > >>
            > >> Hi John,
            > >>
            > >> If you don't set the rate explicitly, the final layer will be
            > > numerically
            > >> lossless. The bit-rates of the other layers will be
            automatically
            > >> deduced from that of the final (lossless) layer, via the
            > > logarithmic
            > >> spacing approach I mentioned. If you specify the bit-rates
            > > explicitly,
            > >> you must be sure to specify a "-" for the last quality layer,
            > > rather than
            > >> just a very high bit-rate, if you want truly lossless.
            > >>
            > >> Cheers,
            > >>
            > >> David
            > >>
            > >> ----- Original Message -----
            > >> From: "novakjohnj" <john.j.novak@>
            > >> To: <kakadu_jpeg2000@yahoogroups.com>
            > >> Sent: Thursday, December 21, 2006 12:29 AM
            > >> Subject: [kakadu_jpeg2000] Re: Kakadu 5.2.2: Layers, Levels,
            > > Reversible
            > >>
            > >>
            > >> >
            > >> > Hi,
            > >> >
            > >> > Yes, that's what I observed during my testing. I have a
            > >> > specification that requires the compressed image to be
            visually
            > >> > lossless at 18 layers and numerically lossless at 19. The
            last
            > > can
            > >> > be handled simply by setting Creversible=yes. However, if I
            > > don't
            > >> > set the flag (default is no) what is the default rate? Can I
            > > expect
            > >> > a visually lossless image when I get to layer 18?
            > >> >
            > >> > Thanks, John
            > >> >
            > >> > --- In kakadu_jpeg2000@yahoogroups.com, "jratike80"
            > >> > <jukka.rahkonen@> wrote:
            > >> >>
            > >> >> Hi,
            > >> >>
            > >> >> Number of quality layers does not have any effect on the
            final
            > >> > quality
            > >> >> of compression. That it determined by the -rate parameter.
            > >> > Number of
            > >> >> quality layers is just telling how many more compressed
            > > versions of
            > >> >> the image are calculated inside the codestream.
            > >> >>
            > >> >> The only way to achieve a real lossless compression is to use
            > >> >> 'Creversible=yes' argument. If that is set you will get a
            > > lossless
            > >> >> compression even with just one quality layer. If fact having
            > > just
            > >> > one
            > >> >> quality layer seems to be more common than having quite a
            many
            > > as
            > >> >> instructed in Kakadu examples. For example ER Mapper jpeg2000
            > >> >> compressor defaults to having one quality layer.
            > >> >>
            > >> >> Advantage in having many quality layers is that is enables
            > > quality
            > >> >> progressive browsing, so with just minor part of the
            codestream
            > >> > read
            > >> >> you can see the image, first with poor quality that is
            getting
            > >> > better
            > >> >> and better while you receive more data (quality layers) from
            the
            > >> >> codestream. Not many image browsers have support for this
            kind
            > > of
            > >> >> quality progressive reading. Kdu_show is one of them. If
            > > browser
            > >> >> does not support quolity progressive reading then I believe
            that
            > >> >> having many quality layers in the jpeg2000 image does not
            give
            > > any
            > >> >> advantage for the user.
            > >> >>
            > >> >> If you consider using JPIP protocol some day for serving
            > > jpeg2000
            > >> >> images quality layers would be nice to have. For local use
            it
            > > is
            > >> > not
            > >> >> so necessary.
            > >> >>
            > >> >> Regards
            > >> >>
            > >> >> -Jukka Rahkonen-
            > >> >>
            > >> >>
            > >> >>
            > >> >> --- In kakadu_jpeg2000@yahoogroups.com, "novakjohnj"
            > >> >> <john.j.novak@> wrote:
            > >> >> >
            > >> >> > I've seen references to using 19 (visually lossless) and
            20
            > >> >> > (numerically lossless) layers during compression. With
            > > Kakadu,
            > >> > I
            > >> >> > still need to set 'Creversible=yes' to obtain a
            numerically
            > >> > lossless
            > >> >> > compressed image. I've noticed that with that option set,
            I
            > > can
            > >> >> > achieve numerically lossless compression with a lower
            layers
            > >> > count.
            > >> >> > How do these parameters relate to each other in the
            > > compressor?
            > >> > Is
            > >> >> > there a recommendation on when 'Creversible=yes' should be
            > > used?
            > >> >> >
            > >> >> > Thanks, John
            > >> >> >
            > >> >>
            > >> >
            > >> >
            > >> >
            > >> >
            > >> > For problems with your subscription in this group please
            email
            > >> > kakadu_jpeg2000-owner@yahoogroups.com
            > >> >
            > >> > Yahoo! Groups Links
            > >> >
            > >> >
            > >> >
            > >> >
            > >>
            > >
            > >
            > >
            > >
            > > For problems with your subscription in this group please email
            > > kakadu_jpeg2000-owner@yahoogroups.com
            > >
            > > Yahoo! Groups Links
            > >
            > >
            > >
            > >
            >
          • David Taubman
            Hi John, Multiply bpppb by the number of bands and the number of pixels in the image (spatially) to get the total number of bits, over the image. Divide this
            Message 5 of 8 , Jan 10, 2007
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              Hi John,

              Multiply bpppb by the number of bands and the number of pixels
              in the image (spatially) to get the total number of bits, over the image.
              Divide this by 8 to get the number of bytes and those are the values
              you pass to `flush'.

              Cheers,

              david

              ----- Original Message -----
              From: "novakjohnj" <john.j.novak@...>
              To: <kakadu_jpeg2000@yahoogroups.com>
              Sent: Thursday, January 11, 2007 12:05 AM
              Subject: [kakadu_jpeg2000] Re: Kakadu 5.2.2: Layers, Levels, Reversible


              > Hi David,
              >
              > Okay, I've looked at this but I still need some advice (i.e.,
              > help). My requirements are Layer 0: 0.03125 bpppb, Layer 1: 0.0625
              > bpppb, Layer 2: 0.125 bpppb, ..., Layer 18: 3.5 bpppb, Layer 19:
              > Numerically Lossless. 'bpppb' is bits per pixel per band. Layer 18
              > is Visually Lossless. How do I translate the 'bpppb' values into
              > bytes or can these values be passed directly to Kakadu?
              >
              > Thanks, John
              >
              > --- In kakadu_jpeg2000@yahoogroups.com, "David Taubman"
              > <d.taubman@...> wrote:
              >>
              >> HI John,
              >>
              >> No problem. This is done via the `kdu_codestream::flush' function.
              >> Amongst other things, this function accepts an array of lengths
              >> (measured in bytes) for each quality layer. Actually, each length
              >> corresponds to the total number of bytes in that layer and all
              >> previous layers. If you leave an entry equal to 0, the relevant
              > length
              >> is calculated using the logarithmic progression I mentioned. If
              >> you leave the last entry 0, the final layer will be lossless. The
              >> function can also be driven directly by a collection of supplied
              >> distortion-length slope thresholds for each layer, or else it can
              >> be driven by the lengths and return the slopes. For more on all
              >> this, look at the documentation of the `kdu_codestream::flush'
              > function
              >> (I suggest you ignore the material on incremental flushing for the
              >> time being, since that is more complex).
              >>
              >> If you are using `kdu_stripe_compressor' as a higher level
              >> compression engine, you do not call `kdu_codestream::flush'
              >> directly, but you pass the same parameters into the `start'
              >> function -- these are all optional arguments, so read the function
              >> descriptions.
              >>
              >> Cheers,
              >>
              >> David
              >>
              >>
              >> ----- Original Message -----
              >> From: "novakjohnj" <john.j.novak@...>
              >> To: <kakadu_jpeg2000@yahoogroups.com>
              >> Sent: Friday, December 22, 2006 5:48 AM
              >> Subject: [kakadu_jpeg2000] Re: Kakadu 5.2.2: Layers, Levels,
              > Reversible
              >>
              >>
              >> > Hi David,
              >> >
              >> > Your explanation is useful. However, I cannot figure out how to
              >> > specify the bit-rates to the compressor for each layer in the
              > core
              >> > SDK. I am not using the kdu_compress application.
              >> >
              >> > Thanks, John
              >> >
              >> > --- In kakadu_jpeg2000@yahoogroups.com, "David Taubman"
              >> > <d.taubman@> wrote:
              >> >>
              >> >> Hi John,
              >> >>
              >> >> If you don't set the rate explicitly, the final layer will be
              >> > numerically
              >> >> lossless. The bit-rates of the other layers will be
              > automatically
              >> >> deduced from that of the final (lossless) layer, via the
              >> > logarithmic
              >> >> spacing approach I mentioned. If you specify the bit-rates
              >> > explicitly,
              >> >> you must be sure to specify a "-" for the last quality layer,
              >> > rather than
              >> >> just a very high bit-rate, if you want truly lossless.
              >> >>
              >> >> Cheers,
              >> >>
              >> >> David
              >> >>
              >> >> ----- Original Message -----
              >> >> From: "novakjohnj" <john.j.novak@>
              >> >> To: <kakadu_jpeg2000@yahoogroups.com>
              >> >> Sent: Thursday, December 21, 2006 12:29 AM
              >> >> Subject: [kakadu_jpeg2000] Re: Kakadu 5.2.2: Layers, Levels,
              >> > Reversible
              >> >>
              >> >>
              >> >> >
              >> >> > Hi,
              >> >> >
              >> >> > Yes, that's what I observed during my testing. I have a
              >> >> > specification that requires the compressed image to be
              > visually
              >> >> > lossless at 18 layers and numerically lossless at 19. The
              > last
              >> > can
              >> >> > be handled simply by setting Creversible=yes. However, if I
              >> > don't
              >> >> > set the flag (default is no) what is the default rate? Can I
              >> > expect
              >> >> > a visually lossless image when I get to layer 18?
              >> >> >
              >> >> > Thanks, John
              >> >> >
              >> >> > --- In kakadu_jpeg2000@yahoogroups.com, "jratike80"
              >> >> > <jukka.rahkonen@> wrote:
              >> >> >>
              >> >> >> Hi,
              >> >> >>
              >> >> >> Number of quality layers does not have any effect on the
              > final
              >> >> > quality
              >> >> >> of compression. That it determined by the -rate parameter.
              >> >> > Number of
              >> >> >> quality layers is just telling how many more compressed
              >> > versions of
              >> >> >> the image are calculated inside the codestream.
              >> >> >>
              >> >> >> The only way to achieve a real lossless compression is to use
              >> >> >> 'Creversible=yes' argument. If that is set you will get a
              >> > lossless
              >> >> >> compression even with just one quality layer. If fact having
              >> > just
              >> >> > one
              >> >> >> quality layer seems to be more common than having quite a
              > many
              >> > as
              >> >> >> instructed in Kakadu examples. For example ER Mapper jpeg2000
              >> >> >> compressor defaults to having one quality layer.
              >> >> >>
              >> >> >> Advantage in having many quality layers is that is enables
              >> > quality
              >> >> >> progressive browsing, so with just minor part of the
              > codestream
              >> >> > read
              >> >> >> you can see the image, first with poor quality that is
              > getting
              >> >> > better
              >> >> >> and better while you receive more data (quality layers) from
              > the
              >> >> >> codestream. Not many image browsers have support for this
              > kind
              >> > of
              >> >> >> quality progressive reading. Kdu_show is one of them. If
              >> > browser
              >> >> >> does not support quolity progressive reading then I believe
              > that
              >> >> >> having many quality layers in the jpeg2000 image does not
              > give
              >> > any
              >> >> >> advantage for the user.
              >> >> >>
              >> >> >> If you consider using JPIP protocol some day for serving
              >> > jpeg2000
              >> >> >> images quality layers would be nice to have. For local use
              > it
              >> > is
              >> >> > not
              >> >> >> so necessary.
              >> >> >>
              >> >> >> Regards
              >> >> >>
              >> >> >> -Jukka Rahkonen-
              >> >> >>
              >> >> >>
              >> >> >>
              >> >> >> --- In kakadu_jpeg2000@yahoogroups.com, "novakjohnj"
              >> >> >> <john.j.novak@> wrote:
              >> >> >> >
              >> >> >> > I've seen references to using 19 (visually lossless) and
              > 20
              >> >> >> > (numerically lossless) layers during compression. With
              >> > Kakadu,
              >> >> > I
              >> >> >> > still need to set 'Creversible=yes' to obtain a
              > numerically
              >> >> > lossless
              >> >> >> > compressed image. I've noticed that with that option set,
              > I
              >> > can
              >> >> >> > achieve numerically lossless compression with a lower
              > layers
              >> >> > count.
              >> >> >> > How do these parameters relate to each other in the
              >> > compressor?
              >> >> > Is
              >> >> >> > there a recommendation on when 'Creversible=yes' should be
              >> > used?
              >> >> >> >
              >> >> >> > Thanks, John
              >> >> >> >
              >> >> >>
              >> >> >
              >> >> >
              >> >> >
              >> >> >
              >> >> > For problems with your subscription in this group please
              > email
              >> >> > kakadu_jpeg2000-owner@yahoogroups.com
              >> >> >
              >> >> > Yahoo! Groups Links
              >> >> >
              >> >> >
              >> >> >
              >> >> >
              >> >>
              >> >
              >> >
              >> >
              >> >
              >> > For problems with your subscription in this group please email
              >> > kakadu_jpeg2000-owner@yahoogroups.com
              >> >
              >> > Yahoo! Groups Links
              >> >
              >> >
              >> >
              >> >
              >>
              >
              >
              >
              >
              > For problems with your subscription in this group please email
              > kakadu_jpeg2000-owner@yahoogroups.com.
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              >
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