Digital zoom

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Zooming
Digital zoom was used to make the middle photo from the top photo, image quality is lost, while the lens was zoomed-in optically for the bottom photo, no quality is lost. Typically, the digital zoom would not be available until after the optical zoom had been exhausted.

Digital zoom is a method of decreasing (narrowing) the apparent angle of view of a digital photographic or video image, quality is reduced except for optical zoom. Digital zoom is accomplished by cropping an image down to a centered area with the same aspect ratio as the original, and usually also interpolating the result back up to the pixel dimensions of the original. It is accomplished electronically, with no adjustment of the camera's optics, and no optical resolution is gained in the process. This enlargement of the pixels also creates a pixelation/mosaic effect in the image.

When comparing the image quality achieved by digital zoom with image quality achieved by resizing the image in post-processing, there's a difference between cameras that perform potentially lossy image compression like JPEG, and those that save images in an always lossless Raw image format. In the former case, digital zoom tends to be superior to enlargement in post-processing, because the camera may apply its interpolation before detail is lost to compression. In the latter case, resizing in post-production yields results equal or superior to digital zoom.

Some digital cameras rely entirely on digital zoom, lacking a real zoom lens, as on most camera phones. Other cameras do have a real zoom lens, but apply digital zoom automatically once its longest focal length has been reached. Professional cameras generally do not feature digital zoom.

Since 2012 high end Nokia smartphones have used advance digital zoom, called by Nokia as PureView which use data binning or to combine more than one pixels which near each other into a single pixel. With megapixel and data binning, so we can produce digital zoom image quality same with the optical zoom, but the resolution certainly decreasing depends on the magnifications. It is useful to produce a good quality small size zoom image.

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