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{{Short description|Magnification of a digital image}} {{More citations needed|date=July 2020}}[[File:Zoom.gif|thumb|Zooming]] [[Image: Digital zoom example.png|thumb|right|Digital zoom has been used to create the middle photo from within the top photo. The image quality has been lost. No quality is lost however, with the lens zoomed-in optically for the bottom photo. Typically, the digital zoom is not available until the optical zoom has been exhausted.]] '''Digital zoom''' is a method of decreasing the precise [[angle of view]] of a [[Digital photography|digital photograph]] or [[Video|video image]]. It is accomplished by [[Cropping (image)|cropping]] an image down to an area with the same [[aspect ratio (image)|aspect ratio]] as the original, and [[Scaling (geometry)|scaling]] the image up to the dimensions of the original. The camera's optics are not adjusted. It is accomplished electronically, so no [[optical resolution]] is gained.{{Citation needed|date=August 2021}} Digital zooming may be enhanced by computationally expensive algorithms which sometimes involves artificial intelligence.<ref>{{cite web | url=https://ieeexplore.ieee.org/abstract/document/8500290/keywords#keywords |title= Image Zooming Using Corner Matching |access-date=May 5, 2018}}</ref> In cameras that perform [[lossy compression]], digital zoom is preferred to enlargement in post-processing, as the zooming may be applied before detail is lost to compression. In cameras that save in a lossless format, resizing in post-production yields results equal or superior to digital zoom.{{Citation needed|date=August 2021}} Lower-end [[camera phone]]s use only digital zoom and do not have optical zoom, while many higher-end phones have [[Smartphone#Cameras|additional rear cameras]], including fixed telephoto lenses that allow for the simulation of optical zoom. Full-sized cameras generally have an [[optical zoom]] lens, but some apply digital zoom automatically once the longest optical [[focal length]] possible has been reached. Professional cameras generally do not feature digital zoom.{{Citation needed|date=August 2021}} ==Not-deteriorated zoom limit== An [[optical zoom]] camera can be zoomed to its optical limit, and further zooming is sometimes allowed by digital zoom. Digital zoom uses the centre area of the optical image to enlarge the image. By reducing the image size, digital zoom occurs without image deterioration of the output image, and some cameras have a "not-deteriorated image" mode or an image deterioration indicator.<ref>{{cite |title=Casio EXILIM EX-H50 User Manual: Shooting With Zoom}}</ref><ref>{{cite |title=Casio EXILIM EX-H50 User Manual |page= 43 }}</ref> The table below shows the not-deteriorated zoom limit for some [[Pixel#Megapixel|megapixel]] (MP) image sizes of a particular camera with optical zoom 24x, and digital zoom 4x for its maximum capability: {| class="wikitable" align="center" style="text-align: center" ! Image size ! Maximum zoom factor ! Not-deteriorated zoom limit ! Magnification of digital zoom |- | 16 MP | 96.0Γ | 24.0Γ | 1.0Γ |- | 10 MP | 121.2Γ | 30.2Γ | 1.3Γ |- | 5 MP | 172.8Γ | 43.2Γ | 1.8Γ |- | 3 MP | 215.5Γ | 54.0Γ | 2.25Γ |- | VGA | 382.6Γ | 172.8Γ | 7.2Γ |} <gallery mode="nolines"> File:Zoom10x.JPG|Handheld. Zoom 10Γ, Optical zoom 10Γ, 2 MP from 16 MP maximum, ISO 800, 1/420, F/14.0, image is clear File:Zoom28x.JPG|Handheld. Zoom 28Γ, Optical zoom 10Γ, and Digital zoom 2.8Γ, 2 MP from 16 MP maximum, ISO 800, 1/420, F/14.0, initial of deteriorated digital zoom, image is still clear File:Zoom40x.JPG|Handheld. Zoom 40Γ, Optical zoom 10Γ, and Digital zoom 4.0Γ, 2 MP from 16 MP maximum, ISO 800, 1/500, F/14.0, image is still clear with some noise. Magnification in deteriorated digital zoom zone is 40Γ : 28 = 1.4Γ File:Zoom72x.JPG|Handheld. Zoom 72Γ, Optical zoom 10Γ, and Digital zoom 7.2Γ, 2 MP from 16 MP maximum, ISO 800, 1/640, F/14.0, more noise, but the detail is still clear. Magnification in deteriorated digital zoom zone is 72Γ : 28 = 2.6Γ File:Zoom72xFullResolutionResize.JPG|Handheld. Zoom 72Γ, Optical zoom 10Γ and Digital zoom 7.2Γ taken in full resolution 16 MP, but resize to 2 MP for uploading, ISO 800, 1/680, F/14.0, more noise, but the detail is more clear. Magnification in deteriorated digital zoom zone is 72Γ: 10 = 7.2Γ, the bigger the number, the worse the image </gallery> Some camera [[firmware]]s store lossily digitally zoomed images with accordingly reduced dimensions (width and height) rather than upscaling it to the original [[Raster graphics|raster]] resolution. The benefits are reduced file sizes and the ability to calculate the zoom level from the image's dimensions, if not included in its [[meta data]].{{Citation needed|date=August 2021}} Cameras may have an intelligent zoom feature that allows an additional magnification of 2.0Γ on top of its optical zoom. Many cameras have 2 options: 1.4Γ and 2.0Γ.{{Citation needed|date=May 2020}} The intelligent zoom only uses the centre of the [[image sensor]] and does not interpolate the original resolution, so the resulting image quality is good in reduced resolution.<ref name=cisco /> Hybrid zoom is a concept used in smartphones that takes advantage of optical zoom, digital zoom, and software to get improved results when zooming in further than the lens' physical capabilities.<ref>{{Cite web|date=2020-05-05|title=Camera zoom explained: How optical, digital, and hybrid zoom work|url=https://www.androidauthority.com/camera-zoom-optical-digital-hybrid-1021264/|access-date=2020-07-16|website=Android Authority|language=en-US}}</ref> Smartphones with optical zoom have lenses with 3Γ or 5Γ magnification. Trying to zoom in further than this limit may result in loss of quality as the camera switches to digital zoom, though hybrid zoom may mitigate this. Many cameras, including [[mobile phone camera]]s, also employ lossless digital zoom for video recording by using the spare resolution of the image sensor for cropping by taking advantage of used video frame resolutions often being significantly below the available resolution of the image sensors.<ref name="cisco" /> This means that, for example, if implemented correctly by the camera hardware and software, a [[2160p]] image sensor would enable up to 2Γ lossless digital zoom for [[1080p]] video recording, 3Γ for [[720p]] video, and 4.5Γ for [[480p]] video by using image sensor cropping. The terms among camera and image sensor manufacturers are "Smart Zoom" ([[Sony]]), "Safe Zoom" ([[Canon Inc.|Canon]]), "Sensor Crop" ([[Cisco]])<ref name=cisco>[https://meraki.cisco.com/blog/2018/11/getting-lossless-zoom-with-sensor-crop/ ''Getting lossless zoom with sensor crop'' - Cisco Meraki blog]</ref> and "Intelligent Zoom" ([[Panasonic]] and others).<ref>{{cite web |url=http://www.photoxels.com/digital-photography-tutorials/optical-digital-zoom/ |title=Optical vs. Digital Zoom |access-date=February 27, 2015}}</ref> There are also cameras with digital zoom functions as high as 7.2Γ and Smart Zoom with approximately 30Γ total zoom (optical zoom 20Γ and digital zoom 1.5Γ) for 7MP from 16MP total resolution, and also 144Γ total zoom (optical zoom 20Γ and digital zoom 7.2Γ) for VGA 640x480.<ref>{{cite web | url=http://www.tabloidpulsa.co.id/kamera/compact-digital/pentax/3808-pentax-optio-vs20 | title=Pentax Optio VS20Hot | access-date=June 6, 2015 | archive-date=February 2, 2015 | archive-url=https://web.archive.org/web/20150202232449/http://www.tabloidpulsa.co.id/kamera/compact-digital/pentax/3808-pentax-optio-vs20 | url-status=dead }}</ref> ==Aesthetic== Photographers can purposefully employ digital zoom for the characteristic low-fidelity appearance of the images it produces.<ref>{{cite web |url=http://nymag.com/selectall/2016/07/how-i-learned-to-love-digital-zoom.html |title=How I Learned to Love Digital Zoom |access-date=October 14, 2016 |date=July 12, 2016 }}</ref> The appearance of poor quality in photographs can be intentionally used to imply carelessness on the part of the photographer and a sense of candidness in the photograph. == See also == * [[Image scaling]] * [[Teleside converter]] β a secondary lens made for fixed lenses that increases the focal length, uses as a filter * [[Zoom lens]] ==References== {{Reflist}} {{DEFAULTSORT:Digital Zoom}} [[Category:Digital photography]]
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