Editing Screen magnifier

{{Short description|Software that enlarges image on part of a computer screen}}
[[File:Kmagnifier screenshot.gif|thumb|Rendering this very page with [[Firefox]], and magnifying its upper left corner with ''kmag'']]
A '''screen magnifier''' is software that interfaces with a computer's graphical output to present enlarged screen content. By enlarging part (or all) of a screen, people with visual impairments can better see words and images. This type of [[assistive technology]] is useful for people with some functional vision; people with [[visual impairment]]s and little or no functional vision usually use a [[screen reader]].

==Use==
The simplest form of magnification presents an enlarged portion of the original screen content, the 'focus', so that it covers some or all of the full screen. This enlarged portion should include the content of interest to the user and the pointer or cursor, also suitably enlarged. As the user moves the pointer or cursor the screen magnifier should track with it and show the new enlarged portion. If this tracking is jerky or [[Flicker (screen)|flickers]] it is likely to disturb the user. Also, the pointer or cursor may not be the content of interest: for example, if the user presses a [[keyboard shortcut]]s that opens a menu, the magnified portion should jump to that menu. Pop-up windows and changes in system status can also trigger this rapid shifting.

Screen magnifiers can be especially helpful for people with low vision, including elderly users. However, in a 2001 paper, [[Vicki Hanson]] noted that people with low vision often also have additional disabilities such as tremors.<ref>
{{cite book
| chapter-url = http://dl.acm.org/citation.cfm?doid=564526.564531
| author = V. L. Hanson
| title = Proceedings of the 2001 EC/NSF workshop on Universal accessibility of ubiquitous computing providing for the elderly - WUAUC'01
| chapter = Web Access for Elderly Citizens
| year = 2001
| page = 14
| publisher = Proceedings of the workshop on Universal accessibility of ubiquitous computing
| doi = 10.1145/564526.564531
| isbn = 158113424X
| s2cid = 290610
| access-date = 2017-02-14
}}
</ref>

==Features==
Ranges of 1- to 16-times magnification are common. The greater the magnification the smaller the proportion of the original screen content that can be viewed, so users will tend to use the lowest magnification they can manage.{{cn|date=July 2022}}

Screen magnifiers commonly provide several other features for people with particular sight difficulties:
* '''Color inversion'''. Many people with visual impairments prefer to invert the colors, typically turning text from black-on-white to white-on-black. This can reduce screen glare and is useful for elderly people with [[Macular degeneration|age-related macular degeneration]].
* '''Smoothing'''. Text can become blocky and harder to recognise when enlarged. Some screen magnifiers use [[interpolation]] to smooth the text to compensate.
* '''Cursor customisation'''. The mouse and text cursors can often be modified in several ways, such as circling it to help the user locate it on the screen.
* '''Different magnification modes'''. Screen magnifiers can alter how they present the enlarged portion: covering the full screen, providing a lens that is moved around the un-magnified screen, or using a fixed magnified portion.
* '''Crosshairs'''. Even with magnification, some users can find the mouse pointer hard to see. Crosshairs – especially when their size, color and opacity are customizable – can make the use of a pointing device easier.
* '''Screen reader'''. Some magnifiers come packaged with a basic [[screen reader]], allowing whatever the user is pointing at to be read out.

==Screen magnifiers bundled with an operating system==
* [[Haiku (operating system)|Haiku]] includes an application called Magnify<ref>{{cite web|title=Haiku User Guide - Magnify|url=http://www.haiku-os.org/docs/userguide/en/applications/magnify.html | accessdate = 2010-05-11}}</ref>
* [[Linux]]-based operating systems:
** [[Compiz|Compiz-Fusion]] window manager has a highly configurable plugin named "Enhanced Zoom Desktop"
** [[GNOME]] has gnome-mag, which {{as of | 2015 | lc = on}} forms part of [[GNOME Shell]]<ref>GNOME Project: [https://wiki.gnome.org/Projects/GnomeShell/Magnification Magnification in GNOME Shell]</ref>
** [[KDE]] has KMagnifier (KMag)
* The [[Microsoft Windows]] operating system has included the [[Magnifier (Windows)|"Magnifier"]] application since [[Windows 98]] (released in 1998). It can integrate with a mouse-button toggle.<ref>
{{cite web
| url = http://www.microsoft.com/hardware/en-us/help/support/how-to/mouse/magnifier
| archive-url = https://web.archive.org/web/20160608225048/http://www.microsoft.com/hardware/en-us/help/support/how-to/mouse/magnifier
| title = How-to: Mouse Magnifier
| year = 2015
| website = Microsoft Hardware
| publisher = Microsoft
| access-date = 2015-04-16
| archive-date = 2016-06-08
| quote = If the Magnify command was not assigned to a button on your mouse by default, you can assign it to one. [...] To turn on or turn off the Magnifier[:] Click the mouse button assigned to Magnify.
| url-status=dead
}}
</ref>
* In [[OS X]], the built-in screen magnification feature can be used at any time by using keyboard shortcuts or by scrolling with a mouse or trackpad.<ref>{{cite web
| url = https://support.apple.com/kb/PH21496?locale=en_US
| title = OS X El Capitan: Zoom options in Accessibility preferences
| year = 2016
| publisher = Apple
| access-date = 2017-02-14
}}
</ref><ref>{{cite web
| url = https://support.apple.com/kb/PH18385?locale=en_US
| title = OS X Yosemite: Zoom pane of Accessibility preferences
| year = 2015
| publisher = Apple
| access-date = 2017-02-14
}}
</ref> Screen magnification is built into iOS devices as well.<ref>{{cite web
| url = https://support.apple.com/en-us/HT204390
| title = Use Accessibility features in iOS
| year = 2016
| publisher = Apple
| access-date = 2017-02-14
}}
</ref>

==Stand-alone screen magnifier products==
* [[Virtual Magnifying Glass]] - Cross-platform, open-source magnifier application
* [[Magic (screen magnifier)|MAGic]]{{Citation needed|date=November 2023}}

==External links==
* {{cite web | archive-url=https://web.archive.org/web/20140317102058/http://www.rnib.org.uk/livingwithsightloss/computersphones/pc/accessibility/assistive/Pages/free_windows_magnification.aspx | url=http://www.rnib.org.uk/livingwithsightloss/computersphones/pc/accessibility/assistive/Pages/free_windows_magnification.aspx | title=Free Windows magnification | date=3 March 2014 | archive-date=17 March 2014 | url-status=dead }}—a comparison of freely-downloadable magnifiers for Windows.

==See also==
* [[Fresnel lens]]
* [[Magnifying glass]]

==References==
{{Reflist}}

{{DEFAULTSORT:Screen Magnifier}}
[[Category:Assistive technology]]
[[Category:Screen magnifiers| ]]