Image metadata (was: imagemmagick patch 5)

[Juri Linkov]

>>>> it returns a raw representation of the extension data of a given 
>>>> (sub)image.
>>> Again, what is meant by "extension" here?
>> It seems the term "extension" is GIF-specific.  The GIF specification says
>> that extension blocks "extend" the 87a definition to allow extensions like
>> the Graphic Control Extension that specifies the animation delay time, etc.
>
>> The parameter `count' is used in animation, but unrelated to "extension".
>> Perhaps a more common term for `count' would be "metadata".
>
> Then we should rename image-extension-data to image-metadata, I think.

The problem is that one part of the current `image-extension-data'
is metadata, and another part is extension data.  For instance, in

  (count 44
   255 "NETSCAPE2.0"
     0 "address@hidden@"
   249 "address@hidden"
  )

`count 44' is metadata, and the rest (with non-descriptive numeric keys)
is extension data.

Maybe the list returned by the new function `image-metadata' should be like:

  (count 44
   extension-data (255 "NETSCAPE2.0"
                     0 "address@hidden@"
                   249 "address@hidden")
  )

-- 
Juri Linkov
http://www.jurta.org/emacs/