rfc2531.txt

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

         IETF



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RFC 2531        Content Feature Schema for Internet Fax       March 1999


A.5 CIELAB color depth

   -  Media Feature tag name(s):

         CIELAB-L-depth
         CIELAB-A-depth
         CIELAB-B-depth

   -  ASN.1 identifiers associated with these feature tags:

         1.3.6.1.8.1.12
         1.3.6.1.8.1.13
         1.3.6.1.8.1.14

   -  Summary of the media features indicated:

         These feature tags indicate a color depth capability; i.e.  the
         level of detail to which an individual CIELAB color component
         can be specified.  They define the number of distinct values
         possible for each of the color components L*, a* and b*.

         Typically, this feature would be used with 'color=mapped', and
         possibly 'color=grey' or 'color=full', to indicate the number
         of distinct colors that can be realized.

   -  Values appropriate for use with these feature tags:

         Integer (>0)

   -  These feature tags are intended primarily for use in the
      following applications, protocols, services, or negotiation
      mechanisms:

         Color image printing and display applications where the data
         resource used may depend upon color handling capabilities of
         the recipient.

         Scanning applications where the data transferred may depend
         upon the image generation capabilities of the originator.

   -  Examples of typical use:

         To describe rendering or scanning capabilities:

         (& (color=mapped) (color-levels<=240)
            (CIELAB-L-depth<=128)
            (CIELAB-a-depth<=128)
            (CIELAB-b-depth<=128) )



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RFC 2531        Content Feature Schema for Internet Fax       March 1999


         (& (color=full) (color-levels<=16777216)
            (CIELAB-L-depth<=256)
            (CIELAB-a-depth<=128)
            (CIELAB-b-depth<=128) )

         To describe capabilities assumed by a document:

         (& (color=mapped) (color-levels=200)
            (CIELAB-L-depth=32)
            (CIELAB-a-depth=32)
            (CIELAB-b-depth=32) )
         (& (color=full) (color-levels=32768)
            (CIELAB-L-depth=128)
            (CIELAB-a-depth=32)
            (CIELAB-b-depth=32) )

   -  Related standards or documents:

         The memo "Media Features for Display, Print, and Fax" [3]
         defines a feature (color) for indicating basic color
         capabilities.

         CIELAB color space is defined in [19]

         CIELAB use for fax is described in ITU T.42 [9]

   -  Related feature tags:

         color                 [3]
         color-levels          [this document]
         color-space           [this document]

   -  Intended usage:

         Internet fax
         Color image scanning/rendering applications

   -  Author/Change controller:

         IETF











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RFC 2531        Content Feature Schema for Internet Fax       March 1999


A.6 CIELAB color gamut

   -  Media Feature tag name(s):

         CIELAB-L-min
         CIELAB-L-max
         CIELAB-a-min
         CIELAB-a-max
         CIELAB-b-min
         CIELAB-b-max

   -  ASN.1 identifiers associated with these feature tags:

         1.3.6.1.8.1.15
         1.3.6.1.8.1.16
         1.3.6.1.8.1.17
         1.3.6.1.8.1.18
         1.3.6.1.8.1.19
         1.3.6.1.8.1.20

   -  Summary of the media features indicated:

         These feature indicate a supported range of color values, by
         indicating minimum and maximum values used for each color
         component in a CIELAB color space.

         'CIELAB-L-min' and 'CIELAB-L-max' are the minimum and maximum
         values of the L* component.

         'CIELAB-a-min' and 'CIELAB-a-max' are the minimum and maximum
         values of the a* component.

         'CIELAB-b-min' and 'CIELAB-b-max' are the minimum and maximum
         values of the b* component.

   -  Values appropriate for use with this feature tag:

         Rational

   -  The feature tag is intended primarily for use in the following
      applications, protocols, services, or negotiation mechanisms:

         Color image printing and display applications where the data
         resource used may depend upon detailed color handling
         capabilities of the recipient.






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RFC 2531        Content Feature Schema for Internet Fax       March 1999


         Scanning applications where the data transferred may depend
         upon the detailed color image generation capabilities of the
         originator.

   -  Examples of typical use:

         To describe rendering or scanning capabilities:

         (& (CIELAB-L-min>=0)
            (CIELAB-L-max<=100)
            (CIELAB-a-min>=-75)
            (CIELAB-a-max<=+75)
            (CIELAB-b-min>=-85)
            (CIELAB-b-max<=+85) )

         To describe capabilities required by a document:

         (& (CIELAB-L-min=20)
            (CIELAB-L-max=80)
            (CIELAB-L-min=-35)
            (CIELAB-L-max=+55)
            (CIELAB-L-min=-45)
            (CIELAB-L-max=+65) )

   -  Related standards or documents:

         CIELAB color space is defined in [19]

         CIELAB use for fax is described in ITU T.42 [9]

   -  Interoperability considerations:

         When describing a recipient's capabilities, the minimum and
         maximum color component values that can be rendered should be
         indicated by inequalities as shown in the examples above.

         When describing a document, the actual minimum and maximum
         color component values used should be indicated, as shown
         above.

   -  Security considerations:

         - Privacy concerns, related to exposure of personal
            information:
            Where feature matching is used to select content applicable
            to the physical abilities of a user, unusual values for this
            feature tag might give an indication of a user's restricted
            abilities.



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RFC 2531        Content Feature Schema for Internet Fax       March 1999


   -  Related feature tags:

         color                 [3]
         color-space           [this document]

   -  Related media types or data formats:

         TIFF-FX               [7]

   -  Intended usage:

         Internet fax
         Color image scanning/rendering applications

   -  Author/Change controller:

         IETF

A.7 Image file structure

   -  Media Feature tag name(s):

         image-file-structure

   -  ASN.1 identifier associated with this feature tag:

         1.3.6.1.8.1.21

   -  Summary of the media features indicated:

         This feature indicates a file structure used for transfer and
         presentation of image data.

         It does not indicate image data coding:  that is described by
         separate feature tags (image-coding, etc.).

   -  Values appropriate for use with this feature tag:

         Token












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RFC 2531        Content Feature Schema for Internet Fax       March 1999


         TIFF-FX profiles  TIFF-S
         [7]:              TIFF-F
                           TIFF-J
                           TIFF-C
                           TIFF-L
                           TIFF-M

                           (may be extended by further registrations,
                           to cover non-TIFF image file structures)

   -  The feature tag is intended primarily for use in the following
      applications, protocols, services, or negotiation mechanisms:

         Internet fax, and other print or display applications that
         transfer image data.

   -  Examples of typical use:

         See Appendix B of this memo.

   -  Considerations particular to use in individual applications,
      protocols, services, or negotiation mechanisms:

         This tag is intended to provide information about an image file
         structure.  Information about image data coding is provided by
         other tags.

         In the case of TIFF-FX image data, there are a number of image
         file format constraints that are imposed by the various usage
         profiles defined in RFC 2301 [7].  The purpose of the 'image-
         file-structure' feature tag is to capture those file format
         constraints.

         Registration of additional image file structure tags should
         focus similarly on image file structure issues, not raw image
         data compression and coding.  As a guide, an image file
         structure may contain image data coded in a variety of ways,
         and carries information to describe that coding separately from
         MIME content-type labelling, etc.

   -  Related feature tags:

         image-coding          [this document]

   -  Related media types or data formats:

         TIFF-FX               [7]
         TIFF V6.0 (Adobe)     [20]



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RFC 2531        Content Feature Schema for Internet Fax       March 1999


   -  Intended usage:

         Internet fax
         Image scanning/rendering applications

   -  Author/Change controller:

         IETF

A.8 Image data coding

   -  Media Feature tag name(s):

         image-coding

   -  ASN.1 identifier associated with this feature tag:

         1.3.6.1.8.1.22

   -  Summary of the media features indicated:

         This feature tag indicates a form of image data compression and
         coding used.

         It identifies a generic image coding technique used, without
         regard to any specific profiling of that technique that may be
         applied.  Values for this feature are generally applicable
         across a wide range of image transfer applications.

         This information is distinct from the image file structure and
         MRC information conveyed by the 'image-file-structure' tags.

   -  Values appropriate for use with this feature tag:

         Token             MH
                           MR
                           MMR
                           JBIG
                           JPEG

                           (may be extended by further registrations)

   -  The feature tag is intended primarily for use in the following
      applications, protocols, services, or negotiation mechanisms:

         Internet fax, and other applications that transfer image data.





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RFC 2531        Content Feature Schema for Internet Fax       March 1999


   -  E