ICO

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|extensions={{ext|ico}}
 
|extensions={{ext|ico}}
 
|mimetypes={{mimetype|image/vnd.microsoft.icon}}, {{mimetype|image/x-icon}}
 
|mimetypes={{mimetype|image/vnd.microsoft.icon}}, {{mimetype|image/x-icon}}
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|pronom={{PRONOM|x-fmt/418}}
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|kaitai struct=ico
 
}}
 
}}
 
'''ICO''' is a Microsoft Windows icon format.
 
'''ICO''' is a Microsoft Windows icon format.
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Files begin with bytes <code>00 00 01 00</code>.
 
Files begin with bytes <code>00 00 01 00</code>.
  
Note that this byte sequence is not very discriminating. For example, many [[JBIG]] files begin the same way.
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Note that this byte sequence is not very discriminating. Other formats that can begin this way include [[Macintosh resource file]] and [[JBIG]].
  
 
== Changing default icons for Windows file types ==
 
== Changing default icons for Windows file types ==
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== See also ==
 
== See also ==
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* [[BMP]]
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* [[CUR]]
 
* [[Favicon]]
 
* [[Favicon]]
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* [[OS/2 Icon]]
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* [[Windows 1.0 Icon]]
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 +
== Software ==
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Many image viewers and web browsers support ICO format.
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* [http://www.nongnu.org/icoutils/ icoutils] (icotool)
  
 
== Sample files ==
 
== Sample files ==
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== References ==
 
== References ==
* [http://en.wikipedia.org/wiki/ICO_%28file_format%29 ICO (Wikipedia)]
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* [[Wikipedia:ICO %28file format%29|ICO (Wikipedia)]]
* The evolution of the ICO file format: [http://blogs.msdn.com/b/oldnewthing/archive/2010/10/18/10077133.aspx part 1], [http://blogs.msdn.com/b/oldnewthing/archive/2010/10/19/10077610.aspx part 2], [http://blogs.msdn.com/b/oldnewthing/archive/2010/10/21/10078690.aspx part 3], [http://blogs.msdn.com/b/oldnewthing/archive/2010/10/22/10079192.aspx part 4]
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* [https://web.archive.org/web/20070423201738/http://www.oreilly.com/www/centers/gff/formats/miccur/index.htm GFF Format Summary: Microsoft Windows Cursor and Icon] (from archive.org)
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* The evolution of the ICO file format: [https://blogs.msdn.microsoft.com/oldnewthing/20101018-00/?p=12513 part 1], [https://blogs.msdn.microsoft.com/oldnewthing/20101019-00/?p=12503 part 2], [https://blogs.msdn.microsoft.com/oldnewthing/20101021-00/?p=12483 part 3], [https://blogs.msdn.microsoft.com/oldnewthing/20101022-00/?p=12473 part 4]
 
* [http://www.winhelponline.com/blog/change-file-type-icon-windows-7-vista/ Changing default file icons in Vista and Win7]
 
* [http://www.winhelponline.com/blog/change-file-type-icon-windows-7-vista/ Changing default file icons in Vista and Win7]
  
 
[[Category:Microsoft]]
 
[[Category:Microsoft]]
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[[Category:Windows]]

Latest revision as of 15:31, 15 September 2019

File Format
Name ICO
Ontology
Extension(s) .ico
MIME Type(s) image/vnd.microsoft.icon, image/x-icon
PRONOM x-fmt/418
Kaitai Struct Spec ico.ksy

ICO is a Microsoft Windows icon format.

ICO files can have multiple icon images of different sizes and color types in the same file, so that programs displaying them can pick the best image for a particular use.

Contents

[edit] Format

An ICO file begins with a 6-byte header, followed one or more 16-byte directory entries (one for each image). Each entry contains information about the image's size, color format, and location in the file.

The rest of the file contains the actual images, which usually use a variant of BMP format (without the file header, and with a transparency mask). Alternatively, they may use PNG format.

ICO format is very similar to CUR (cursor) format.

[edit] Identification

Files begin with bytes 00 00 01 00.

Note that this byte sequence is not very discriminating. Other formats that can begin this way include Macintosh resource file and JBIG.

[edit] Changing default icons for Windows file types

Versions of Windows up through XP had a nice and simple means of changing default icons for file types through the properties tab you can pull up for any file/folder. However, Microsoft in its infinite wisdom (or wisdumb?) decided to change that starting in Vista, removing the option and making the changing of icons something that practically requires a PhD in computer science. (Changing icons for folders is still a simple option, but not for files.) If you want to try it, here's how:

  • Run Registry Edit (Regedit.exe from the start menu)
  • Navigate to HKEY_CURRENT_USER \ Software \ Microsoft \ Windows \ CurrentVersion \ Explorer \ FileExts \ .ext \ UserChoice, where .ext is replaced by the file extension you are trying to modify
  • If no UserChoice item exists here, go up one level to the one named after the extension you're looking for.
  • Note the value of this field, which is what the file type in question is known as to Windows.
  • Now go to HKEY_CLASSES_ROOT \ yourfiletype \ DefaultIcon in Registry Edit, where yourfiletype is replaced with the value found in the extension data above.
  • Change the value here to the path/filename of the desired icon. If no DefaultIcon item exists, create one under the file type.
  • Icon paths can be the name of a .ico file, or an .exe or .dll that contains an icon; in cases where multiple icon images are in a file, the name needs to be suffixed with a comma and a number which gives the index of the icon within the file, where 0 is the first one. The icon picker which you can get while changing icons for a folder/directory can be helpful here; if you choose an exe/dll file, it shows all icons in the file and if you count from left to right and top to bottom you can determine the index of the one you want.

[edit] See also

[edit] Software

Many image viewers and web browsers support ICO format.

[edit] Sample files

[edit] References

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