Digital zoom and image crop — both are widely used features in photography to enhance the attention accorded to the subject. The former is utilized while the image is being taken, while the latter is accomplished at post production. Which one is better? Let’s find out.
This feature is a restricted form of cropping usually found in digital point-and-shoot cameras and mobile phones with cameras. It is used to magnify the subject of interest further using the camera’s internal software. The digital zoom feature will operate after reaching the maximum optical zooming range of the camera.
For example, a camera may have an optical zooming range of 25-300mm. Supposing you want to zoom in further on the subject, you will either have to move closer or, if that is not possible, use the digital zoom feature. By using the digital zoom, the camera can magnify further by 2x, 3x or 4x and so on, depending on the camera’s specification. At 2x, you are viewing the subject at twice the maximum optical zoom rating or equivalent to 600mm (2 x 300mm). It does this by magnifying the center image focus and cropping the sides. You will end up with two results depending on your camera’s digital zoom capability:
- The cropped image is saved resulting in a smaller file size.
- The most common method is using interpolation software — the cropped image is magnified back to the original size of the uncropped image.
Using the second method, the digital zoom does not capture any additional detail. Instead it adds extra pixels during interpolation to make the image larger. In short, it guesses how it can add the new pixels to create an illusion of increased detail.
Some cameras have improved firmware which minimizes the noise created when the image is cropped and magnified. Usually this is guaranteed at 2x magnification. Beyond this range, the image degrades significantly in quality. Noise and pixelation becomes more apparent. Also at this magnified zoom range, a slight movement of the camera affects the image, causing significant blur.
This is usually done during post-production on the computer using photography software. This is carried out to enhance the composition of the subject by removing unnecessary details in the image. It also creates a zoomed or magnified effect. It can be of any size and can be taken from any part of the original image. Because the user has a choice of a variety of algorithms to use when interpolating the image compared to a camera, the results are usually better in quality. And if you end up not liking the result, it is still reversible. Also, since you are working on a copy, you can still retain the original image—something which is not possible using digital zoom.
Both the digital zoom and image cropping methods have advantages and disadvantages. It’s up to you as the user to choose which application best suits your purposes. Are you the type who uploads images on to social networking sites without post-processing your image? Then digital zoom may work for you. Or are you the type who has the time and the skill to enhance your images thru post-processing?
In the end you as the user may have to weigh which method works best for you. And which one produces the desired results you want.