Thumbs.db

Microsoft Windows

Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...

operating system

Operating system

An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

s (starting with Windows 2000), a thumbnail cache is used to store thumbnail

Thumbnail

Thumbnails are reduced-size versions of pictures, used to help in recognizing and organizing them, serving the same role for images as a normal text index does for words...

images for Windows Explorer

Windows Explorer

This article is about the Windows file system browser. For the similarly named web browser, see Internet ExplorerWindows Explorer is a file manager application that is included with releases of the Microsoft Windows operating system from Windows 95 onwards. It provides a graphical user interface...

's thumbnail view. This speeds up the display of images as the smaller images do not need to be recalculated every time the user views the folder.

Purpose

Windows stores thumbnails of graphics files, and certain document and movie files, in the Thumbnail Cache file, including the following formats: JPEG

JPEG

In computing, JPEG . The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and image quality. JPEG typically achieves 10:1 compression with little perceptible loss in image quality....

, BMP, GIF, PNG, TIFF

Tagged Image File Format

TIFF is a file format for storing images, popular among graphic artists, the publishing industry, and both amateur and professional photographers in general. As of 2009, it is under the control of Adobe Systems...

, AVI

Audio Video Interleave

Audio Video Interleave , known by its acronym AVI, is a multimedia container format introduced by Microsoft in November 1992 as part of its Video for Windows technology. AVI files can contain both audio and video data in a file container that allows synchronous audio-with-video playback...

, PDF

Portable Document Format

Portable Document Format is an open standard for document exchange. This file format, created by Adobe Systems in 1993, is used for representing documents in a manner independent of application software, hardware, and operating systems....

, PPTX

Microsoft PowerPoint

Microsoft PowerPoint, usually just called PowerPoint, is a non-free commercial presentation program developed by Microsoft. It is part of the Microsoft Office suite, and runs on Microsoft Windows and Apple's Mac OS X operating system...

, DOCX

Microsoft Word

Microsoft Word is a word processor designed by Microsoft. It was first released in 1983 under the name Multi-Tool Word for Xenix systems. Subsequent versions were later written for several other platforms including IBM PCs running DOS , the Apple Macintosh , the AT&T Unix PC , Atari ST , SCO UNIX,...

, HTML

HTML

HyperText Markup Language is the predominant markup language for web pages. HTML elements are the basic building-blocks of webpages....

and many others. Its purpose is to prevent intensive CPU processing and load times when a folder that contains a large number of files is set to display each file as a thumbnail. This effect is more clearly seen when accessing a DVD containing thousands of photos without the thumbs.db file and setting the view to show thumbnails next to the filenames. Thumbnail caching was introduced in Windows 2000 ; wherein the thumbnails were stored in the image file's Alternate Data Stream if the operating system was installed on a drive with the NTFS

NTFS

NTFS is the standard file system of Windows NT, including its later versions Windows 2000, Windows XP, Windows Server 2003, Windows Server 2008, Windows Vista, and Windows 7....

file system. A separate Thumbs.db file was created if Windows 2000 was installed on a FAT32 volume. Windows Me

Windows Me

Windows Millennium Edition, or Windows Me , is a graphical operating system released on September 14, 2000 by Microsoft, and was the last operating system released in the Windows 9x series. Support for Windows Me ended on July 11, 2006....

also created Thumbs.db files. Beginning with Windows XP, thumbnail caching and thus, creation of Thumbs.db can optionally be turned off from Windows Explorer View Menu, Folder Options and checking "Do not cache thumbnails" on the View tab. Under Windows 2000, Windows Me and Windows XP, a context menu command to force refresh the thumbnail is available by right clicking the image in Thumbnail view of Windows Explorer.

Thumbs.db files are stored in each directory that contains thumbnails on Windows systems. The file is created locally among the images, however, preventing system wide use of the data and creating additional data load on removable devices. Windows XP Media Center Edition also creates ehthumbs.db which holds previews of video files. Each thumbnail created in a directory is represented in this database file as a small JPEG file, regardless of the file's original format. The images are resized to 96×96 pixels by default or a proportional miniature of their original shape for non-square images, with 96 pixels on the longer side. The size can be controlled by a setting on Windows Registry. Each folder with initiated thumbnail views (that is where they have displayed a Thumbnails or Filmstrip view in Windows Explorer) will have a Thumbs.db file. Folders with pictures also display previews on their icon when displayed in Thumbnail mode – the first four images in the folder at 40×40 pixels (or proportionally shaped), with a 1-pixel divider overlaid on a standard large folder icon. The Thumbs.db file is stored in OLE Compound Document

Object Linking and Embedding

Object Linking and Embedding is a technology developed by Microsoft that allows embedding and linking to documents and other objects. For developers, it brought OLE Control eXtension , a way to develop and use custom user interface elements...

format, the same format that many Microsoft Office

Microsoft Office

Microsoft Office is a non-free commercial office suite of inter-related desktop applications, servers and services for the Microsoft Windows and Mac OS X operating systems, introduced by Microsoft in August 1, 1989. Initially a marketing term for a bundled set of applications, the first version of...

products use.

Thumbnail cache

Beginning with Windows XP

Windows XP

Windows XP is an operating system produced by Microsoft for use on personal computers, including home and business desktops, laptops and media centers. First released to computer manufacturers on August 24, 2001, it is the second most popular version of Windows, based on installed user base...

, thumbnail previews are stored in a centralized location on the system. This provides the system with access to images independent of their location, and addresses issues with the locality of Thumbs.db files. The cache is stored at %userprofile%\AppData\Local\Microsoft\Windows\Explorer as a number of files with the label thumbcache_xxx.db (numbered by size); as well as an index used to find thumbnails in each sized database.

However, when browsing network shares with write permission, Windows Vista and Windows 7 store a Thumbs.db file in the remote directory instead of using the (local) central thumbnail cache. This can cause issues when deleting remote shares, as the directory will become locked for a period of time when selected as Windows Explorer automatically creates a remote Thumbs.db file.

Creating Thumbs.db files on remote shares can be disabled with a Group Policy setting.

FBI

The FBI has been using this file to prove that illicit photos were previously stored on the hard drive. The FBI used the "thumbs.db" file in 2008 as evidence of viewing depictions of child pornography

Child pornography

Child pornography refers to images or films and, in some cases, writings depicting sexually explicit activities involving a child...

External links

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.