GIF Metadata Format Specification

jim153

               
GIF Image Metadata Format Specification
The GIF image metadata format encodes the image descriptor, local
color table, and extension information assciated with a single image
within a GIF file, typically a frame of an animation.
The image description contains the offset of the frame within the
logical screen described in the stream metadata, as well as the width
and height of the frame and whether it is used interlaced encoding.
The local color table, if present, supersedes the global color table
for the frame at hand.
The graphic control extension contains information on how the frame is
to be incorporated into the animation.  The disposal method indicates
whether the current frame should remain in place
(doNotDispose), be restored to the backgound color as
specified in the stream metadata
(restoreToBackgroundColor), or be restored to the
previous frame contents (restoreToPrevious) prior to
displaying the subsequent frame.
The user input flag indicates whether the animation should pause for
user input before advancing to the next frame.  The transparent color
flag and index indicate a color index for which pixels of the frame
should not be drawn.  The delay time indicates how long the frame
should be displayed, in hundredths of a second.  If the user input
flag is set and the delay time is 0, the frame is intended to be
advanced only on user input.
   
      
      
        
        
        
        
      
        
        
        
        
      
        
        
        
        
      
        
        
        
        
      
        
   
      
      
      
      
        
      
        
      
        
        
         
         
         
         
        
         
         
         
         
        
         
         
         
         
        
         
         
         
         
   
      
      
        
      
        
      
        
      
        
        
        
        
      
        
        
        
        
   
      
      
        
        
        
        
      
        
        
        
        
      
        
        
        
        
      
        
        
        
        
      
        
        
        
        
      
        
        
        
        
      
        
        
        
        
      
        
        
        
        
   
      
      
      
      
        
        
        
        
        
         
         
        
         
         
   
      
      
      
      
        
        
         
         
]>
Mapping of Standard to GIF Native Stream Metadata
Standard Metadata Component
GIF Native Stream Metadata Component
/Chroma/Palette/PaletteEntry@index
/GlobalColorTable/ColorTableEntry@index
/Chroma/Palette/PaletteEntry@red
/GlobalColorTable/ColorTableEntry@red
/Chroma/Palette/PaletteEntry@green
/GlobalColorTable/ColorTableEntry@green
/Chroma/Palette/PaletteEntry@blue
/GlobalColorTable/ColorTableEntry@blue
/Chroma/BackgroundIndex@value
/GlobalColorTable@backgroundColorIndex
/Data/BitsPerSample@value
/LogicalScreenDescriptor@colorResolution
/Dimension/PixelAspectRatio@value
/LogicalScreenDescriptor@pixelAspectRatio
/Dimension/HorizontalScreenSize@value
/LogicalScreenDescriptor@logicalScreenWidth
/Dimension/VerticalScreenSize@value
/LogicalScreenDescriptor@logicalScreenHeight
/Document/FormatVersion@value
/Version@value
Mapping of Standard to GIF Native Image Metadata
Standard Metadata Component
GIF Native Image Metadata Component
/Chroma/Palette/PaletteEntry@index
/LocalColorTable/ColorTableEntry@index
/Chroma/Palette/PaletteEntry@red
/LocalColorTable/ColorTableEntry@red
/Chroma/Palette/PaletteEntry@green
/LocalColorTable/ColorTableEntry@green
/Chroma/Palette/PaletteEntry@blue
/LocalColorTable/ColorTableEntry@blue
/Dimension/HorizontalPixelOffset@value
/ImageDescriptor@imageLeftPosition
/Dimension/VerticalPixelOffset@value
/ImageDescriptor@imageTopPosition
/Text/TextEntry@value
/CommentExtensions/CommentExtension@value
/Transparency/TransparentIndex@value
/GraphicControlExtension@transparentColorIndex
(/GraphicControlExtension@transparentColorFlag is also set to
"TRUE")
               
               
               
               
               

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