# Video magnifier

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**Video magnifiers** are electronic devices that use a camera and a display screen to perform digital [magnification](/source/Magnification) of printed materials. The display screen is usually [LCD](/source/LCD) or a similar [flat-screen](/source/Flat-panel_display) technology (although older video magnifiers have used [CRT](/source/Cathode_ray_tube) displays), and the device usually includes a [lamp](/source/Lamp_(electrical_component)) to illuminate the source material. Video magnifiers are designed to be mostly used by people with [low vision](/source/Low_vision) that cannot be helped using a conventional [magnifying glass](/source/Magnifying_glass).

## Advantages

### Magnification range and display size

The main benefit of a video magnifier over purely optical magnification is that the video magnifier allows greater magnification across a larger [field of view](/source/Angle_of_view_(photography)). With [optical lenses](/source/Optical_lenses), the field of meaningful, [in-focus](/source/Focus_(optics)) view is reduced with increased magnification. Thus, while a "full page magnifier" based on a [fresnel lens](/source/Fresnel_lens) can span some 625 cm2 (96.9 sq in) ([A4](/source/A4_paper)), it typically achieves no more than 1.4x magnification (advertised as "2x" if measured by area instead of the [scale factor](/source/Scaling_(geometry))); an [aspheric segment](/source/Aspheric_segment) hand magnifier can achieve a scale factor in excess of two (area factor in excess of four) but typically measures no more than 10 x 3 cm, and higher magnification factors require conventional lenses that focus on a very small area. A video magnifier however is limited only by its display size and its electronics; video magnifiers that can be switched between 2 and 50 times magnification are common, and displays can range from [smartphone](/source/Smartphone)-sized to [TV](/source/Television)-sized.

### Image processing

Most video magnifiers can [automatically focus](/source/Autofocus) the image, and the more advanced models are capable of further electronic [image processing](/source/Digital_image_processing) to change the colours, enhance the [contrast](/source/Contrast_(vision)), and/or assist in the tracking of images. Some can be set to save "snapshots" of previously seen images.

## Disadvantages

### Power requirements

Video magnifiers require power, either via [mains electricity](/source/Mains_electricity) or from a [battery](/source/Battery_(electricity)). This may make battery life an issue if the magnifier is required for an extended period of time away from power, whereas a purely optical magnification device could be used indefinitely without needing to be connected to power.

### Non-portability of the larger models

Very large video magnifiers are not typically portable, but they can still be used in home installations, libraries and classrooms. Some of these models are informally referred to as [CCTV](/source/Closed-circuit_television) magnifiers.

### Pricing

As of 2013, video magnifiers are typically several times more expensive than optical-only magnifiers.

## Software video magnifiers

Due to the high cost of dedicated-hardware video magnifiers, there has been some interest in software video magnification running on [smartphones](/source/Smartphone) such as [iPhone](/source/IPhone)[1] and [Android](/source/Android_(operating_system)),[2] [tablets](/source/Tablet_computer) such as [iPad](/source/IPad),[3] and [laptops](/source/Laptop) with suitably-mounted camera peripherals.[4][5] Software magnifiers might not achieve the same quality as a good hardware video magnifier, and if used extensively they might exhaust the battery quickly, but if the user already has a smartphone, tablet or laptop then software magnification can be more economical than obtaining a separate hardware video magnifier.

## References

1. Rempel, John (December 2013). ["A Comparative Review of iPhone Magnifier Apps"](https://web.archive.org/web/20140910195353/http://www.afb.org/afbpress/pub.asp?DocID=aw141204). *AccessWorld*. **14** (12). [American Foundation for the Blind](/source/American_Foundation_for_the_Blind). Archived from [the original](http://www.afb.org/afbpress/pub.asp?DocID=aw141204) on 10 September 2014. Retrieved 12 June 2014. This review compares Super Vision+, See It Video Magnifier, Magnifier Magnifying Glass, BigMagnify, Magnifying Glass with Light Pro, and the built-in camera app.

1. Android magnifier apps include Zoom Plus, Magnify It, Magnify, Magnifying Glass, Real Magnifier, Ideal Magnifier, etc, but it seems a comparative review of these Android apps has not yet been published.

1. Rempel, John (August 2012). ["Can the iPad and an App Replace Electronic Magnifiers (CCTVs)? An Evaluation of SightTech's EyeSight App"](https://web.archive.org/web/20141111104355/http://www.afb.org/afbpress/pub.asp?DocID=aw130803). *AccessWorld*. **13** (8). [American Foundation for the Blind](/source/American_Foundation_for_the_Blind). Archived from [the original](http://www.afb.org/afbpress/pub.asp?DocID=aw130803) on 11 November 2014. Retrieved 12 June 2014.

1. Wei, Jiawei (5 April 2010). ["zh:兄弟合力替視障者開啟新「視」界"](http://www.peopo.org/news/49520) [Brothers join forces to open new "vision" for the visually impaired] (in Chinese). *輔大生命力新聞 ([Fu Jen Catholic University](/source/Fu_Jen_Catholic_University) Life-Force News)*. Taiwan: [Public Television Service Foundation](/source/Public_Television_Service_Foundation). Retrieved 12 June 2014. See also the [download page for their software](https://sites.google.com/site/apollocctv/download) (in Chinese).

1. Hughes, Gregory & Robinson, Peter (April 2008). *Photonote: The making of a classroom adaptation system*. Cambridge Workshop on Universal Access and Assistive Technology. pp. 197–206. ISBN 978-1-84800-210-4. See also Hughes, Gregory & Robinson, Peter (October 2007). [*Photonote evaluation: aiding students with disabilities in a lecture environment*](http://www.cl.cam.ac.uk/~pr/publications/assets07a.pdf). ACM Conference on Computers and Accessibility. Also Hughes, Gregory & Robinson, Peter (October 2006). [*Lecture adaptation for students with visual disabilities using high-resolution photography*](http://www.cl.cam.ac.uk/~pr/publications/assets06.pdf). ACM Conference on Computers and Accessibility.

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Adapted from the Wikipedia article [Video magnifier](https://en.wikipedia.org/wiki/Video_magnifier) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Video_magnifier?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.