In photography, Bokeh is the aesthetic quality of the blur produced in the out-of-focus parts of an image produced by a lens. Bokeh has been defined as “the way the lens renders out-of-focus points of light”. This has become one of the most popular subjects in photography today, mostly due to the fact that many smartphones now are trying to implement a form of taking such photos. Another reason why it is so popular could be because Bokeh makes photographs visually appealing, forcing us to focus our attention on a particular area of the image, the subject.
A few things we need to know about Bokeh, bokeh is the quality of out-of-focus or “blurry” parts of the image rendered by a camera lens – it is NOT the blur itself or the amount of blur in the foreground or the background of a subject. The blur that you are so used to seeing in photography that separates a subject from the background is the result of shallow “depth of field” and is generally simply called “background blur”.
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All lenses are capable of producing out of focus blur, but not all lenses are capable of rendering beautiful bokeh. Generally, portrait and telephoto lenses with large maximum apertures yield more pleasant-looking bokeh than zoom lenses. While this is true for dedicated DSLR cameras, the same principle applies to smartphones.
Bokeh in Smartphones
Of course, we may not be able to cram in full-size lenses on our smartphones so Bokeh in smartphones is achieved using other methods. One of the ways this can be achieved is the reason you have been seeing tons of new devices with two or even three camera lenses at the back. Also, over the past several years, smartphones have learned to create a background blur effect via software.
Also Read: Why New Smartphones come with Dual Camera
Using two cameras with different apertures and focal length
I know most of you are familiar with the effect ‘Close one eye and your depth perception only works to a limited degree.’ We need both eyes to perceive depth. Similarly, for phones to be able to do any variable depth/focusing tasks, they need two cameras.
The dual cameras of Huawei, Honor, Nokia and Motorola use identical focal lengths for each of the two sensors, making bokeh functionality available for wide-angle photos. But this isn’t the only purpose for these secondary cameras. Flagships have an additional purpose for the camera: For instance, on the Huawei Mate 10 Pro, the second sensor takes high-resolution black-and-white photos to supplement the rear camera’s RGB shots with additional brightness information. Its purpose is to improve image quality, particularly when using digital zoom. On the other hand, the second camera on the OnePlus 5T is intended to provide assistance when taking nighttime shots.
Bokeh with one lens
The first phone that comes to mind is the Google Pixel 2, the smartphone that disapproved everyone by being able to put out exceptional quality Bokeh shots with just one camera in a world where everyone else needed two lenses to take any form of Bokeh shot.
One feature of the IMX362 image sensor is helpful here, namely the dual-pixel autofocus. It divides every single pixel on the sensor into two halves and, like on dual cameras, this process makes it possible to generate two slightly shifted images. However, the technological implementation is more complex than with the two individual sensors, since the offset is not in the centimetre range, but rather equal to half of the lens diameter.
The actual pixel generation process here combines a complete set of photos from the depth map and furthermore uses AI-supported image analysis.
For a long time, beautiful Bokeh effect photos were exclusive to the expensive DSLR cameras. That isn’t the case anymore. There are now many different ways to take background blurs, even with small image sensors and the mini-lenses found in smartphone cameras. With better sensors and richer software to support, these smartphones are only going to get better at taking these DSLR-like shots. I might not be much of a photographer but I really am excited for the future of mobile photography.