Digital zoom is a method of decreasing the precise

angle of view The angle of view is the decisive variable for the visual perception of the size or projection of the size of an object. Angle of view and perception of size The perceived size of an object depends on the size of the image projected onto the ...

of a

digital photograph Digital photography uses cameras containing arrays of electronic photodetectors interfaced to an analog-to-digital converter (ADC) to produce images focused by a lens, as opposed to an exposure on photographic film. The digitized image is s ...

or video image. It is accomplished by cropping an image down to an area with the same aspect ratio as the original, and 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 Optical resolution describes the ability of an imaging system to resolve detail, in the object that is being imaged. An imaging system may have many individual components, including one or more lenses, and/or recording and display components. ...

is gained. Digital zooming may be enhanced by computationally expensive algorithms which sometimes involves artificial intelligence. In cameras that perform

lossy compression In information technology, lossy compression or irreversible compression is the class of data compression methods that uses inexact approximations and partial data discarding to represent the content. These techniques are used to reduce data size ...

, 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. Lower-end

camera phone A camera phone is a mobile phone which is able to capture photographs and often record video using one or more built-in digital cameras. It can also send the resulting image wirelessly and conveniently. The first commercial phone with color cam ...

s use only digital zoom and do not have optical zoom, while many higher-end phones have 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 The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power. A positive focal length indicates that a system converges light, while a negative foca ...

possible has been reached. Professional cameras generally do not feature digital zoom.

Not-deteriorated zoom limit

optical zoom A zoom lens is a mechanical assembly of lens elements for which the focal length (and thus angle of view) can be varied, as opposed to a fixed-focal-length (FFL) lens (see prime lens). A true zoom lens, also called a parfocal lens, is one th ...

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. The table below shows the not-deteriorated zoom limit for some

megapixel In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device. In most digital display devices, pixels are the smal ...

(MP) image sizes of a particular camera with optical zoom 24x, and digital zoom 4x for its maximum capability: File:Zoom10x.JPG, Handheld. Zoom 10×, Optical zoom 10×, 2 MP from 16 MP maximum, ISO 800, 1/420, F/14.0, image is clear File:Zoom28x.JPG, Handheld. Zoom 28×, Optical zoom 10×, and Digital zoom 2.8×, 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 40×, Optical zoom 10×, and Digital zoom 4.0×, 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 40× : 28 = 1.4× File:Zoom72x.JPG, Handheld. Zoom 72×, Optical zoom 10×, and Digital zoom 7.2×, 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 72× : 28 = 2.6× File:Zoom72xFullResolutionResize.JPG, Handheld. Zoom 72×, Optical zoom 10× and Digital zoom 7.2× 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 72×: 10 = 7.2×, the bigger the number, the worse the image Some camera

firmware In computing, firmware is a specific class of computer software that provides the low-level control for a device's specific hardware. Firmware, such as the BIOS of a personal computer, may contain basic functions of a device, and may provide h ...

s store lossily digitally zoomed images with accordingly reduced dimensions (width and height) rather than upscaling it to the original

raster Raster may refer to: * Raster graphics, graphical techniques using arrays of pixel values * Raster graphics editor, a computer program * Raster scan, the pattern of image readout, transmission, storage, and reconstruction in television and compu ...

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 Metadata is "data that provides information about other data", but not the content of the data, such as the text of a message or the image itself. There are many distinct types of metadata, including: * Descriptive metadata – the descriptive ...

. Cameras may have an intelligent zoom feature that allows an additional magnification of 2.0× on top of its optical zoom. Many cameras have 2 options: 1.4× and 2.0×. The intelligent zoom only uses the centre of the

image sensor An image sensor or imager is a sensor that detects and conveys information used to make an image. It does so by converting the variable attenuation of light waves (as they pass through or reflect off objects) into signals, small bursts of curr ...

and does not interpolate the original resolution, so the resulting image quality is good in reduced resolution. 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. Smartphones with optical zoom have lenses with 3× or 5× 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 cameras, 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. This means that, for example, if implemented correctly by the camera hardware and software, a

2160p 4K resolution refers to a horizontal display resolution of approximately 4,000 pixels. Digital television and digital cinematography commonly use several different 4K resolutions. In television and consumer media, 38402160 (4K UHD) is the dominan ...

image sensor would enable up to 2× lossless digital zoom for

1080p 1080p (1920×1080 progressively displayed pixels; also known as Full HD or FHD, and BT.709) is a set of HDTV high-definition video modes characterized by 1,920 pixels displayed across the screen horizontally and 1,080 pixels down the screen vert ...

video recording, 3× for

720p 720p (1280×720 px; also called HD ready, standard HD or just HD) is a progressive HDTV signal format with 720 horizontal lines/1280 columns and an aspect ratio (AR) of 16:9, normally known as widescreen HDTV (1.78:1). All major HDTV broadcast ...

video, and 4.5× for

480p 480p is the shorthand name for a family of video display resolutions. The p stands for progressive scan, i.e. non-interlaced. The ''480'' denotes a vertical resolution of 480 pixels, usually with a horizontal resolution of 640 pixels and 4:3 ...

video by using image sensor cropping. The terms among camera and image sensor manufacturers are "Smart Zoom" (

Sony , commonly stylized as SONY, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan. As a major technology company, it operates as one of the world's largest manufacturers of consumer and professional ...

), "Safe Zoom" (

Canon Canon or Canons may refer to: Arts and entertainment * Canon (fiction), the conceptual material accepted as official in a fictional universe by its fan base * Literary canon, an accepted body of works considered as high culture ** Western ca ...

), "Sensor Crop" (

Cisco Cisco Systems, Inc., commonly known as Cisco, is an American-based multinational digital communications technology conglomerate corporation headquartered in San Jose, California. Cisco develops, manufactures, and sells networking hardware, ...

)''Getting lossless zoom with sensor crop'' - Cisco Meraki blog
/ref> and "Intelligent Zoom" (

Panasonic formerly between 1935 and 2008 and the first incarnation of between 2008 and 2022, is a major Japanese multinational corporation, multinational Conglomerate (company), conglomerate corporation, headquartered in Kadoma, Osaka, Kadoma, Osaka P ...

and others). There are also cameras with digital zoom functions as high as 7.2× and Smart Zoom with approximately 30× total zoom (optical zoom 20× and digital zoom 1.5×) for 7MP from 16MP total resolution, and also 144× total zoom (optical zoom 20× and digital zoom 7.2×) for VGA 640x480.

Aesthetic

Photographers can purposefully employ digital zoom for the characteristic low-fidelity appearance of the images it produces. 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.

References

Digital photography {{Photo-stub

Not-deteriorated zoom limit

Aesthetic

See also

References