rfc2879.txt

<VC++网络游戏建摸与实现>源代码

   equal x- and y- resolutions for a multi-level image.

      (& (image-file-structure=TIFF)
         (MRC-mode=0)
         (| (& (color=Binary)
               (| (image-coding=[MH,MR,MMR])
                  (& (image-coding=JBIG)
                     (image-coding-constraint=JBIG-T85)
                     (JBIG-stripe-size=128) ) )
               (| (& (dpi=204) (dpi-xyratio=[204/98,204/196]) )
                  (& (dpi=200) (dpi-xyratio=[200/100,1]) )
                  (& (dpi=300) (dpi-xyratio=1) ) )
            (& (color=Grey)
               (color-levels<=256)
               (color-space-CIELAB)
               (color-illuminant=D50)
               (CIELAB-L-min>=0)
               (CIELAB-L-max<=100)
               (| (& (image-coding=JPEG)
                     (image-coding-constraint=JPEG-T4E) )
                  (& (image-coding=JBIG)
                     (image-coding-constraint=JBIG-T43)



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RFC 2879      Content Feature Schema for Internet Fax (V2)   August 2000


                     (JBIG-stripe-size=128)
                     (image-interleave=stripe) ) )
               (dpi=[100,200,300]) (dpi-xyratio=1) ) )
         (size-x<=2150/254)
         (paper-size=[letter,A4,B4]) )
         (ua-media=stationery) )

4.4 Full-color Internet fax system (JPEG only)

   This adds 24-bit full-color to the previous example.

      (& (image-file-structure=TIFF)
         (MRC-mode=0)
         (| (& (color=Binary)
               (image-coding=[MH,MR,MMR])
               (| (& (dpi=204) (dpi-xyratio=[204/98,204/196]) )
                  (& (dpi=200) (dpi-xyratio=[200/100,1]) )
                  (& (dpi=300) (dpi-xyratio=1) ) ) )
            (& (color=grey)
               (image-coding=JPEG)
               (image-coding-constraint=JPEG-T4E)
               (color-levels<=256)
               (color-space=CIELAB)
               (color-illuminant=D50)
               (CIELAB-L-min>=0)
               (CIELAB-L-max<=100)
               (dpi=[100,200,300]) (dpi-xyratio=1) )
            (& (color=full)
               (image-coding=JPEG)
               (image-coding-constraint=JPEG-T4E)
               (color-subsampling=["1:1:1","4:1:1"])
               (color-levels<=16777216)
               (color-space=CIELAB)
               (color-illuminant=D50)
               (CIELAB-L-min>=0)
               (CIELAB-L-max<=100)
               (CIELAB-a-min>=-85)
               (CIELAB-a-max<=85)
               (CIELAB-b-min>=-75)
               (CIELAB-b-max<=125)
               (dpi=[100,200,300]) (dpi-xyratio=1) ) )
         (size-x<=2150/254)
         (paper-size=[letter,A4,B4]) )
         (ua-media=stationery) )







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RFC 2879      Content Feature Schema for Internet Fax (V2)   August 2000


4.5 Full-color Internet fax system (JPEG and JBIG)

   This adds limited CMY(K), RGB and 16-bit mapped color using JBIG
   coding to the previous example.

      (& (image-file-structure=TIFF)
         (MRC-mode=0)
         (| (& (color=Binary)
               (| (image-coding=[MH,MR,MMR])
                  (& (image-coding=JBIG)
                     (image-coding-constraint=JBIG-T85)
                     (JBIG-stripe-size=128) ) )
               (| (& (dpi=204) (dpi-xyratio=[204/98,204/196]) )
                  (& (dpi=200) (dpi-xyratio=[200/100,1]) )
                  (& (dpi=300) (dpi-xyratio=1) ) ) )
            (& (color=Limited)
               (image-coding=JBIG)
               (image-coding-constraint=JBIG-T43)
               (JBIG-stripe-size=128)
               (image-interleave=stripe)
               (| (& (color-space=[Device-RGB,Device-CMY])
                     (color-levels<=8) )
                  (& (color-space=Device-CMYK)
                     (color-levels<=16) ) )
               (dpi=[100,200,300]) (dpi-xyratio=1) )
            (& (color=Mapped)
               (image-coding=JBIG)
               (image-coding-constraint=JBIG-T43)
               (JBIG-stripe-size=128)
               (image-interleave=stripe)
               (color-levels<=65536)
               (color-space=CIELAB)
               (color-illuminant=D50)
               (CIELAB-L-min>=0)
               (CIELAB-L-max<=100)
               (CIELAB-a-min>=-85)
               (CIELAB-a-max<=85)
               (CIELAB-b-min>=-75)
               (CIELAB-b-max<=125)
               (dpi=[100,200,300]) (dpi-xyratio=1) )
            (& (color=grey)
               (| (& (image-coding=JPEG)
                     (image-coding-constraint=JPEG-T4E) )
                  (& (image-coding=JBIG)
                     (image-coding-constraint=JBIG-T43)
                     (JBIG-stripe-size=128)
                     (image-interleave=stripe) ) )
               (color-levels<=256)



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RFC 2879      Content Feature Schema for Internet Fax (V2)   August 2000


               (color-space=CIELAB)
               (color-illuminant=D50)
               (CIELAB-L-min>=0)
               (CIELAB-L-max<=100)
               (dpi=[100,200,300]) (dpi-xyratio=1) )
            (& (color=full)
               (| (& (image-coding=JPEG)
                     (image-coding-constraint=JPEG-T4E)
                     (color-subsampling=["1:1:1","4:1:1"]) )
                  (& (image-coding=JBIG)
                     (image-coding-constraint=JBIG-T43)
                     (JBIG-stripe-size=128)
                     (image-interleave=stripe) ) )
               (color-levels<=16777216)
               (color-space=CIELAB)
               (color-illuminant=D50)
               (CIELAB-L-min>=0)
               (CIELAB-L-max<=100)
               (CIELAB-a-min>=-85)
               (CIELAB-a-max<=85)
               (CIELAB-b-min>=-75)
               (CIELAB-b-max<=125)
               (dpi=[100,200,300]) (dpi-xyratio=1) ) )
         (size-x<=2150/254)
         (paper-size=[letter,A4,B4]) )
         (ua-media=stationery) )

4.6 Full-color Internet fax system (MRC)

   This adds MRC image structures to the previous example.

      (& (image-file-structure=TIFF-MRC)
         (MRC-mode<=1) (MRC-max-stripe-size>=0)
         (| (& (color=binary)
               (| (image-coding=[MH,MR,MMR])
                  (& (image-coding=JBIG)
                     (image-coding-constraint=JBIG-T85)
                     (JBIG-stripe-size=128) ) )
               (| (& (dpi=204) (dpi-xyratio=[204/98,204/196]) )
                  (& (dpi=200) (dpi-xyratio=[200/100,1]) )
                  (& (dpi=[300,400]) (dpi-xyratio=1) ) ) )
            (& (color=limited)
               (| (& (color-space=[Device-RGB,Device-CMY])
                     (color-levels<=8) ) )
               (| (& (color-space=Device-CMYK)
                     (color-levels<=16) ) )
               (image-coding=JBIG)
               (image-coding-constraint=JBIG-T43)



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RFC 2879      Content Feature Schema for Internet Fax (V2)   August 2000


               (JBIG-stripe-size=128)
               (image-interleave=stripe)
               (dpi=[100,200,300,400]) (dpi-xyratio=1) )
            (& (color=mapped)
               (color-levels<=65536)
               (image-coding=JBIG)
               (image-coding-constraint=JBIG-T43)
               (JBIG-stripe-size=128)
               (image-interleave=stripe)
               (color-space=CIELAB)
               (CIELAB-L-min>=0)
               (CIELAB-L-max<=100)
               (CIELAB-a-min>=-85)
               (CIELAB-a-max<=85)
               (CIELAB-b-min>=-75)
               (CIELAB-b-max<=125) ) )
               (color-illuminant=D50)
               (dpi=[100,200,300,400]) (dpi-xyratio=1) )
            (& (color=grey)
               (| (& (image-coding=JPEG)
                     (image-coding-constraint=JPEG-T4E) )
                  (& (image-coding=JBIG)
                     (image-coding-constraint=JBIG-T43)
                     (JBIG-stripe-size=128)
                     (image-interleave=stripe) ) )
               (color-space=CIELAB)
               (color-levels<=256)
               (color-illuminant=D50)
               (CIELAB-L-min>=0)
               (CIELAB-L-max<=100)
               (dpi=[100,200,300,400]) (dpi-xyratio=1) )
            (& (color=full)
               (| (& (image-coding=JPEG)
                     (image-coding-constraint=JPEG-T4E)
                     (color-subsampling=["1:1:1","4:1:1"]) )
                  (& (image-coding=JBIG)
                     (image-coding-constraint=JBIG-T43)
                     (JBIG-stripe-size=128)
                     (image-interleave=stripe) ) )
               (color-levels<=16777216)
               (color-space=CIELAB)
               (color-illuminant=D50)
               (CIELAB-L-min>=0)
               (CIELAB-L-max<=100)
               (CIELAB-a-min>=-85)
               (CIELAB-a-max<=85)
               (CIELAB-b-min>=-75)
               (CIELAB-b-max<=125)



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RFC 2879      Content Feature Schema for Internet Fax (V2)   August 2000


               (dpi=[100,200,300,400]) (dpi-xyratio=1) ) )
         (size-x<=2550/254)
         (Paper-size=[Letter,A4,B4])
         (ua-media=stationery) )

4.7 Sender and receiver feature matching

   This example considers sending a document to an enhanced black-and-
   white fax system with the following receiver capabilities:

      (& (| (& (dpi=200) (dpi-xyatio=200/100) )
            (& (dpi=200) (dpi-xyratio=1) )
            (& (dpi=300) (dpi-xyratio=1) )
            (& (dpi=400) (dpi-xyratio=1) ) )
         (color=Binary)
         (| (& (paper-size=A4) (ua-media=[stationery,transparency]) )
            (& (paper-size=B4) (ua-media=continuous) ) )
         (image-coding=[MH,MR,JBIG]) )

   Turning to the document itself, assume it is available to the sender
   in three possible formats, A4 high resolution, B4 low resolution and
   A4 high resolution color, described by:

      (& (dpi=300) (dpi-xyratio=1)
         (color=Binary)
         (paper-size=A4)
         (image-coding=[MMR,JBIG]) )

      (& (dpi=200) (dpi-xyratio=200/100)
         (color=Binary)
         (paper-size=B4)
         (image-coding=[MH,MR]) )

      (& (dpi=300) (dpi-xyratio=1)
         (color=Mapped) (color-levels<=256)
         (paper-size=A4)
         (image-coding=JPEG) )

   These three image formats can be combined into a composite capability
   statement by a logical-OR operation (to describe format-1 OR format-2
   OR format-3):

      (| (& (dpi=300) (dpi-xyratio=1)
            (color=Binary)
            (paper-size=A4)
            (image-coding=[MMR,JBIG]) )
         (& (dpi=200) (dpi-xyratio=200/100)
            (color=Binary)



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RFC 2879      Content Feature Schema for Internet Fax (V2)   August 2000


            (paper-size=B4)
            (image-coding=[MH,MR]) )
         (& (dpi=300) (dpi-xyratio=1)
            (color=Mapped) (color-levels=42)
            (paper-size=A4)
            (image-coding=JPEG) ) )

   This could be simplified, but there is little gain in doing so at
   this point.

   The composite document description can be matched with the receiver
   capability description, according to the rules in [2], to yield the
   result:

      (| (& (dpi=300) (dpi-xyratio=1)
            (color=Binary)
            (paper-size=A4)
            (ua-media=[stationery,transparency])
            (image-coding=JBIG) )
         (& (dpi=200) (dpi-xyratio=200/100)
            (color=Binary)
            (paper-size=B4)
            (ua-media=continuous)
            (image-coding=[MH,MR]) ) )

   Points to note about the feature matching process:

   o  The color document option is eliminated because the receiver
      cannot handle either color (indicated by '(color=Mapped)') or
      JPEG coding (indicated by '(image-coding=JPEG)').

   o  The high resolution version of the document with '(dpi=300)' must
      be send using '(image-coding=JBIG)' because this is the only
      available coding of the image data that the receiver can use for
      high resolution documents.  (The available 300dpi document
      codings here are MMR and JBIG, and the receiver capabilities are
      MH, MR and JBIG.)

   o  The low-resolution version of the document can be sent with
      either MH or MR coding as the receiver can deal with either of
      these for low resolution documents.

   o  The high resolution variant of the document is available only for
      A4, so that is the paper-size used in that case.  Similarly the
      low resolution version is sent for B4 paper.

   o  Even though the sender may not understand the 'ua-media' feature
      tag, and does not mention it, the matching rules preserve the



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RFC 2879      Content Feature Schema for Internet Fax (V2)   August 2000


      constraint that the B4 document is rendered with
     '(ua-media=continuous)', and the A4 document may be rendered with
     '(ua-media=[stationery,transparency])'.

   Finally, note that when matching an MRC document description, the
   description of each component sub-image must match the capabilities
   of the intended receiver.

5. IANA Considerations

   Appendix A of this document repeats the descriptions of feature tags
   introduced by RFC 2531 [22], with some small revisions.  These have
   been registered in the "IETF tree", according to the procedure
   described in section 3.1.1 of "Media Feature Tag Registration