SGI (image file format)

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|formattype=electronic
 
|formattype=electronic
 
|subcat=Graphics
 
|subcat=Graphics
|extensions={{ext|sgi}}, {{ext|bw}}, {{ext|rgb}}, {{ext|rgba}}
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|extensions={{ext|sgi}}, {{ext|bw}}, {{ext|rgb}}, {{ext|rgba}}, others
 
|pronom={{PRONOM|x-fmt/140}}
 
|pronom={{PRONOM|x-fmt/140}}
 
|wikidata={{wikidata|Q7514956}}
 
|wikidata={{wikidata|Q7514956}}
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|released=~1995
 
}}
 
}}
'''SGI''' (also known as '''IRIS''', and sometimes called '''RGB''' or '''Irix RGB''') is a raster image file format. The image may be uncompressed, or use [[Run-length encoding|RLE]] compression.
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'''SGI image''' (also known as '''IRIS''', and sometimes called '''RGB''' or '''Irix RGB''') is a raster image file format. It is associated with an image library used on Silicon Graphics workstations. The image may be uncompressed, or use [[Run-length encoding|RLE]] compression.
  
SGI probably stands for '''Silicon Graphics Image'''.
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== Format details ==
  
== Image types ==
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=== File structure ===
SGI supports the following image types:
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SGI image files start with a 512-byte fixed header, most of which is unused. If the image is uncompressed, the pixel data follows. Compressed images have a scan-line table, followed by the compressed pixel data.
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The pixel data is stored bottom-up.
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=== Image types ===
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The following image types are supported:
 
* Grayscale, 8 or 16 bits/sample
 
* Grayscale, 8 or 16 bits/sample
 
* RGB, 8 or 16 bits/sample
 
* RGB, 8 or 16 bits/sample
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* Colormapped (but no palette is stored in the file) (obsolete)
 
* Colormapped (but no palette is stored in the file) (obsolete)
 
* Colormap (file contains only a palette; no image) (obsolete)
 
* Colormap (file contains only a palette; no image) (obsolete)
 
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* Grayscale+alpha images also exist, though they're not covered in the specification.
== Format ==
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SGI files start with a 512-byte fixed header, most of which is unused. If the image is uncompressed, the pixel data follows. Compressed images have a scanline table, followed by the compressed pixel data.
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The pixel data is stored from bottom-up, instead of top-down as in most image formats.
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== Identification ==
 
== Identification ==
SGI files begin with bytes <code>01 DA</code>.
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Files begin with bytes {{magic|01 DA}}.
  
 
== Specifications ==
 
== Specifications ==
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* https://telparia.com/fileFormatSamples/image/sgi/
 
* https://telparia.com/fileFormatSamples/image/sgi/
  
== External links ==
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== Links ==
 
* [[Wikipedia:Silicon Graphics Image|Wikipedia article]]
 
* [[Wikipedia:Silicon Graphics Image|Wikipedia article]]
 
* {{EGFF|sgiimage|SGI Image File Format File Format Summary}}, from the [[Encyclopedia of Graphics File Formats]]
 
* {{EGFF|sgiimage|SGI Image File Format File Format Summary}}, from the [[Encyclopedia of Graphics File Formats]]
  
 
[[Category:Silicon Graphics]]
 
[[Category:Silicon Graphics]]

Revision as of 16:28, 2 December 2022

File Format
Name SGI (image file format)
Ontology
Extension(s) .sgi, .bw, .rgb, .rgba, others
PRONOM x-fmt/140
Wikidata ID Q7514956
Released ~1995

SGI image (also known as IRIS, and sometimes called RGB or Irix RGB) is a raster image file format. It is associated with an image library used on Silicon Graphics workstations. The image may be uncompressed, or use RLE compression.

Contents

Format details

File structure

SGI image files start with a 512-byte fixed header, most of which is unused. If the image is uncompressed, the pixel data follows. Compressed images have a scan-line table, followed by the compressed pixel data.

The pixel data is stored bottom-up.

Image types

The following image types are supported:

  • Grayscale, 8 or 16 bits/sample
  • RGB, 8 or 16 bits/sample
  • RGBA, 8 or 16 bits/sample
  • RGB 3-3-2, 8 bits/pixel (obsolete)
  • Colormapped (but no palette is stored in the file) (obsolete)
  • Colormap (file contains only a palette; no image) (obsolete)
  • Grayscale+alpha images also exist, though they're not covered in the specification.

Identification

Files begin with bytes 01 DA.

Specifications

Software

Sample files

Links

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