Digital zoom
When digital zoom is in contrast to a zoom lens to one on a mathematical method based enlarged by a digital camera or a digital camcorder .
Mode of action
Only part of the active image sensor area and thus the optical image field of the lens is used for the image to be saved , which means that fewer pixels are available. The image section is then often extrapolated back to the nominal image resolution of the image sensor by the firmware , with the missing pixels having to be determined from the adjacent existing pixels (see scaling (computer graphics) ). In the simplest case, this is done by copying an adjacent pixel. By interpolating several neighboring pixels, better results are achieved, but the computational and thus time expenditure for the calculation is sometimes considerably higher. Even if the optical imaging of the lens used is flawless, this is associated with a loss of resolution and thus image quality. The images appear blurred or even pixelated when the view is enlarged accordingly.
Image sensor zoom
Cameras with a large number of pixels and of good optical quality can implement a digital zoom when using image sections without the subsequent image enlargement by the firmware - i.e. with a reduced number of pixels in the saved image. Although the images are not blurred than the corresponding section of the overall picture, the size of the image section and the number of pixels used are reduced, and this procedure does not replace the use of a lens with a larger focal length.
An enlargement corresponding to the digital zoom can also be achieved retrospectively through digital image processing. The disadvantage of this variant is that a slight loss of quality can result from recompressing the images if they were not recorded in a lossless format.
The digital zoom factor is calculated from the ratio of the total available image diagonal to the actually used image diagonal.
A technology is marketed under the name Smart Zoom , which works identically in principle and actually only represents one variant in the operation of the camera.
See also
Web links
- Digital zoom - software magnifier , digital imaging processes , digital images , de.wikibooks.org