✍️ HOW TO ENABLE PORTRAIT MODE ON YOUR SMARTPHONES

Abu_harib · 发表于 2019-05-12 05:04:23

Portrait mode :it’s all the rage. If you’ve been comparison shopping for a new top-of-the-line smartphone lately, you’ve probably seen “portrait mode” advertised in big, bold letters next to RAM, system-on-chip speed, and other headlining specifications. But just what is portrait mode, and what does it have to do with your phone’s camera? And more importantly, how do you enable portrait mode on any phone?[br][br]By [a href="https://www.xda-developers.com/author/kyle-wiggers/"]Kyle Wiggers[/a][br][br]What is portrait mode and how does it work?[br][br]“Portrait mode” isn’t a technical term — it’s marketing shorthand for shallow depth of field, or the range of focus that loses focus the further an object veers to either end of the focal plane (i.e., the plane that’s perpendicular to the axis of the camera lens). Normally, smartphone cameras, which have relatively small sensors compared to the average single-lens (SLR) and digital single-lens (DSLR) shooter, capture everything “in focus” — the background and the foreground of the image look sharp as opposed to blurry. When phone cameras snap a photo in portrait mode, though, they blur parts of the image for a neat stylistic effect.[br][br]On SLRs and DSLRs, shallow depth of field is achieved by narrowing or widening the aperture (the opening of the lens’s diaphragm through which light passes through), which in turn narrows or widens the focal plane. Shooting at a wider aperture, such as f/2.0, lets in more light and achieves more “blur” in front of and behind the subject of an image, while shooting at a narrower aperture, such as f/7.0, lets in less light and results in crisper pictures.[a href="https://en.wikipedia.org/wiki/Circle_of_confusion"]a[/a][br][br]It’s physics. Camera lenses can’t focus light rays perfectly; points of light are rendered as spots on the image sensor rather than points. These spots are called circles of confusion, and when a spot falls outside a range of sharpness (depth of field), it becomes blurred and defocused. Think about it this way: lenses refocus rays of light into cones, and if a ray of light falls perfectly within the focal plane, the resulting cone focuses on the camera’s image sensor really sharply. Narrower apertures allow less light to pass through the lens, focusing the cone and expanding the range at which spots on the image remain in focus.[br][br]You’ve likely heard the word bokeh tossed around in relation to portrait mode. It’s derived from the Japanese word boke, which roughly translates to “haze”, and it’s the aesthetic quality of the blur in the out-of-focus parts of a picture. Generally speaking, bokeh becomes more pronounced at wider apertures.[br][br]Dual Camera Portrait Mode vs. Software Portrait Mode[br][br]Portrait mode on smartphones comes in two flavors: dual-camera portrait mode and software portrait mode.[br][br]Dual-Camera Portrait Mode[br][br]Some smartphone dual-camera setups consist of an RGB sensor, which captures pictures in color, and a monochrome sensor, which snaps pics in black and white. The monochrome sensor works in wide aperture, recording light data that’s subsequently combined with image data from the RGB sensor to create depth of field.[br][br]Other dual camera systems, such as those found on the Samsung [a href="https://forum.xda-developers.com/galaxy-note-8"]Galaxy Note 8[/a] and [a href="https://forum.xda-developers.com/galaxy-s9"]Galaxy S9[/a]+, comprise two RGB lenses (a telephoto lens and wide-angle lens, in the Note 8 and S9+’s cases) with different apertures. They work on the same principle: the image data from the two sensors are combined, lending a degree of depth-of-field flexibility.[br][br]Software Portrait Mode[br][br][br]Portrait Mode on the [a href="https://forum.xda-developers.com/pixel"]Google Pixel[/a] 2. Source: [a href="https://research.googleblog.com/2017/10/portrait-mode-on-pixel-2-and-pixel-2-xl.html"]Google[/a][br][br]By definition, software portrait mode is hardware agnostic. Instead of relying on image data from two camera sensors, software depth of field filters and adjustment sliders use machine learning, computational photography, and algorithms to approximate bokeh effects.[br][br]The [a href="http://xda-developers.com/tag/google-camera"]Google Camera[/a] app on the [a href="http://xda-developers.com/tag/pixel-2"]Pixel 2[/a] and [a href="http://xda-developers.com/tag/pixel-2-xl"]Pixel 2 XL[/a] is one of the best (and most convincing) examples of software portrait mode. First, it captures a series of ten photographs at varying exposures– underexposed (dimly lit), overexposed (brightly lit), and levels in-between — and generates a composite image. That ensures that details and highlights aren’t lost during post-processing.[br][br]Next, the Google Camera uses machine learning to identify the subject of a portrait mode photo. It’s a little complicated, but essentially, Google’s trained artificial intelligence to recognize filter photos for facial features, clothing, and skin by detecting pixel-level differences in color and edges. The result is a stencil-like cutout — a “segmentation mask” — that separates the in-focus foreground subject from the out-of-focus background.[br][br]Finally, in order to mimic the way light behaves in the real world, the Google Camera app creates a depth map by combining imaging data from two sets of pixels on the phones’ camera sensors. The Pixel 2 and Pixel 2 XL’s cameras have Dual Pixel Auto Focus (DPAF) technology: each pixel is divided into two small sub-pixels that capture light from a slightly different angle, which the app uses to determine the distance of objects from the camera.[br][br]How to enable portrait mode on any smartphone[br][br]Now that you have a better understanding of what portrait mode is and how it works, you’re probably wondering how to enable it on your phone. If you have a smartphone with a dual-sensor camera module, you’re in luck: Your phone likely came with some form of portrait mode out of the box. But if you’re stuck with a single-sensor camera, not to worry. Chances are there’s a first-party or third-party software alternative.[br][br]Abu_harib[br][br]The future is now!!![br][br]