Double shot or mainstream: looking at 16 mobile phone photos from Xiaolong 820

IT 168 evaluation 15 thousand yuan mobile phone is very popular in China mobile phone market, and this sentence has been rotten by us, but we still have to mention that thousand yuan mobile phone not only has enough performance to meet daily use, but even elements such as press fingerprint identification and metal body design that were previously exclusive to flagship machine have been delegated to the thousand yuan mobile phone body. Does the popularity of the thousand yuan machine represent the decline of the flagship model? The answer is obviously no. At present, the polarization of the domestic mobile phone market is becoming more and more serious, and flagship models with a price of 3,000 yuan or even more than 4,000 yuan are accepted by more and more people. One of the important factors is the good photo effect. For example, taking photos, user experience, industrial design and other elements are too expensive to be decentralized to the thousand yuan machine market.

Speaking of taking photos, what determines the effect of taking photos with smartphones? In the past two years, consumers will think that pixel value is an intuitive indicator of photo quality. This view is obviously one-sided. As consumers find that there are many products with high pixel and low image quality on the market, there is a new answer to the question of what determines the photo effect of mobile phones: the lens. Technical terms such as Sony lens, IMX2XX, sapphire glass mirror and 6P module appeared at the press conferences of major mobile phone manufacturers. But can a good lens be equated with a good photo? In fact, taking photos with a smart phone is the same as taking photos with a professional camera. Simply put, the decisive factors are: photosensitive element, lens module, processor and algorithm. That is to say, in addition to the hardware such as the lens mentioned earlier, the processor and algorithm are also important factors to determine whether a good photo can be taken.

Can the processor determine the level of photography? This statement may not be familiar to everyone. To give a few simple examples, the dual cameras of HTC One M series are actually the product of cooperation and optimization between HTC and Qualcomm engineers. The laser focusing function of LG G3 is also the hardware support function of Opteron processor ISP. In fact, many mobile phone manufacturers talked about cool camera gameplay at the press conference, which requires the silent support of the processor. As the flagship product of Qualcomm 16, Xiaolong 820 has basically confirmed that many flagship phones of 16 are equipped with this SoC chip. Today, taking this processor as an example, I look forward to the development direction of 16 smartphone photography. You are welcome to leave a message to discuss which aspect of mobile photography disappoints you the most.

Multi-cameras have great potential, and the optical anti-shake function may be gradually popularized.

There have been rumors that the iPhone 7 will be equipped with a rear dual camera configuration, and mobile phones including Qikuo mobile phone and Glory 6 Plus have started to use dual cameras. However, looking at the existing multi-camera mobile phones, the main function is basically to take pictures first and then focus, and the final effect is not very satisfactory. Taking Glory 6plus as an example, Zhao Ming, president of Glory, said that the performance of Glory 6 Plus dual cameras has only released less than 20%. In the early stage, I gave you a large aperture effect and a super night scene mode, and the subsequent software version will release more surprises. Combined with what we said earlier, iPhone 7 will soon be equipped with dual cameras. What breakthroughs will be made in the dual-camera mobile phone in 16?

▲ Dual cameras or solving the optical zoom problem of mobile phones

Optical zoom: In fact, optical zoom is a basic function of SLR cameras and card machines. However, limited by the size of the body, the smart phone can only add optical zoom function at the expense of the thickness of the body, which obviously runs counter to the portable characteristics of the mobile phone. But the addition of dual cameras can skillfully solve this problem. For example, Corephotonics previously claimed that through two different lens groups (a wide-angle lens and a macro lens), three times optical zoom can be achieved without increasing the lens thickness. Corephotonics is also one of the heroes behind HTC's dual cameras.

▲ new features of ▲Spectra ISP

Spectrisp built into Xiaolong 820 processor is also the first image processing engine in the industry that natively supports three cameras to take photos and process at the same time. In other words, mobile phone manufacturers can carry dual cameras without much independent development. In fact, this function has been reflected in Snapdragon 8 10/808 before, which is also an important reason why Qikuo mobile phone and Cool Burton can be equipped with dual cameras.

Fast focusing will become the standard.

More and more people like to take photos with smart phones, and even some professional photographers have begun to create with mobile phones. The main reason is that the mobile phone is suitable for shooting at will and does not need complicated settings. Fast focusing is an important factor to ensure the simple camera experience of mobile phones. With the popularity of terms such as phase focusing, contrast focusing and laser focusing at the press conference of 15 mobile phone manufacturers, consumers began to have a strong interest in the focusing methods of smart phones.

The so-called contrast focusing principle is that when the lens module is randomly moved, the contrast of the picture will increase first and then decrease when the picture becomes clear and then blurred. When ISP recognizes that the contrast drops from the highest point, it drives the lens module back to the state with the highest contrast, thus completing focusing. Phase focusing is to directly perceive the light quantity of the focused object by adding photosensitive pixels on the sensor, so as to directly focus on the accurate position. Although the speed is faster, the disadvantage of phase focusing can also be found in principle: it is difficult to distinguish the light quantity of focused objects and unfocused objects in weak light environment, which leads to the difficulty of focusing. Therefore, even the products such as Apple and Huawei, which currently adopt phase focusing, adopt the dual focusing mode of phase focusing and contrast focusing to ensure fast and accurate focusing.

The principle of laser-assisted focusing is also very simple. When the camera is turned on, the laser transmitter will continuously emit infrared laser, and the receiver is responsible for receiving the light reflected by the infrared laser when it meets the object, and realizing fast focusing by calculating the measurement distance. The principle is very simple. In fact, laser focusing has been used for many years, including ranging telescopes and laser rangefinders. Laser focusing has been used in cameras for a long time. Sony F707 launched on 200 1 has been equipped with holographic laser focusing assistance system. However, due to the excessive power of the laser transmitter, it is easy to cause damage to the photographer's eyes, and it has not been used in subsequent products. Also through the principle, the disadvantage of laser focusing is obvious: distance. The power of laser transmitter directly affects the working distance of laser focusing. The laser focusing sensor of existing mobile phones in the market has low power, which means that the focusing speed of near objects is obviously improved, but the effect on far objects is weak. This is why the word auxiliary should be added before laser focusing.

In 16, the mode of multiple focusing modes and mixed focusing to improve the focusing speed has basically become the mainstream in the smart phone market. For example, phase focusing, contrast focusing, laser focusing and even dual-camera triangle focusing are expected to appear on the same mobile phone and become the standard configuration of flagship smartphones. Xiaolong 820 is also one of the most complete chips supporting focusing mode in the current flagship SoC chip. When everyone is watching the mobile phone manufacturers announce how powerful the focusing speed of their products is at the press conference, they also know that the credit behind the processor is actually huge.

Better dark photo experience

When we evaluate mobile phones, we often say that the sample level is good when the light intensity is good during the day, but it is still unsatisfactory when the light is low at night. It is not because manufacturers do not attach importance to the night shooting experience of mobile phones. But it is limited by the lens hardware itself. Simply put, the larger the photosensitive element and aperture of the camera, the stronger the photographic strength in low illumination. The internal space of the mobile phone can be described as an inch of land, basically leaving no room to increase the size of the camera. So it is not easy to make a breakthrough in taking pictures at night. The author summarizes the following feasible methods:

Breakthrough in camera module structure: In the case that the volume of a single camera module cannot be increased, the industry is developing in two aspects. One is to change the structure of photosensitive element and produce a single photosensitive element similar to Sigma X3 multilayer sensor. The principle is to "change" a layer of photosensitive elements into three layers, respectively sensing three colors of red, green and blue, so that the light input can be tripled when the thickness of the camera module is slightly increased. Another method is the multi-lens shooting mentioned above. In fact, Qikuo mobile phone has achieved the effect of using black and white camera to reduce the noise of shooting at night, increase the luminous flux and improve the white balance. A more radical idea is that the camera groups of the three cameras respectively identify the three primary colors of red, green and blue, and then synthesize them through software algorithms, so as to finally achieve the effect of increasing the brightness purity of the picture in low light.

Software algorithm improvement: Xiaolong 820 has also been specially optimized in low illumination, supporting similar dynamic contrast adjustment function, and automatically improving dark details by recognizing night scenes while ensuring that the bright parts are not exposed. This function has nothing to do with camera hardware.

4K shooting has become mainstream.

If the popularity of the 1080P era is due to the vigorous development of the film and television industry, then the driving force for the arrival of the 4K era comes from the mobile terminals in the hands of every consumer. 13 years, the price of a 4K TV was as high as 20000 RMB, but today, in just two years, the price of 4K TV has dropped to about 4000 RMB. 4K can bring more realistic viewing and reading effects to users, and consumers' viewing and reading behaviors are gradually transferred to mobile terminals, so the arrival of 4K era on mobile terminals is unstoppable. After Snapdragon supported 4K, Samsung, MediaTek and other manufacturers began to support 4K, but so far, the shooting and playback of 4K in H.265(HEVC) format is still exclusive to Qualcomm Snapdragon.

With the support of SOC in Snapdragon, Sony has just launched the world's first commercial 4K screen mobile phone-Sony Z5 Premium. Many consumers say that installing a 4K screen on a smartphone is a waste. In fact, this has returned to the old concept. Hardware is always ahead of software development, and software will optimize hardware. With the gradual popularization of 4K film sources, 4K screens have been used in mobile phones, and large-scale games and software will be optimized for 4K later. With the improvement of network bandwidth and the popularization of 4K TV intelligence, more and more video websites begin to support the playback of 4K film sources, and mobile phones are becoming the main producers of video content.

More and more attention has been paid to low-magnification shooting.

When it comes to the power consumption of mobile phones, the scenes that people think of may be playing games, watching videos on the screen for a long time and so on. In fact, photography and video shooting are also one of the "electric tigers". In fact, the reason is very simple. For example, shooting 4K 60FPS video will process more than 3860 * 2160 * 60 = 500 million pixels per second. Such a big project obviously consumes a lot of electricity. In the past, ISP cooperated with CPU and GPU without a single low-power module, which would lead to high power consumption and low performance. The situation is somewhat similar to the soft decoding and hard decoding of video playback. Soft decoding can't guarantee the smoothness of video while consuming a lot of performance, while hard decoding specializes in decoding several common video coding formats, with low power consumption and smooth image quality. 16 years, with the increase of 4K video, multiple cameras shoot at the same time, and the number of pixels processed per unit time has doubled, so low-power shooting will be paid more and more attention by major mobile phone manufacturers.

Xiaolong 820 also has a layout "early" in low-magnification shooting. Qualcomm has a long history in computing DSP, and the new computing DSP adds support for video function. Another brand-new DSP is a low-power DSP located on a low-power island: LPI). Through the new Hexagon 680 DSP, Qualcomm introduced a new Hexagon architecture, including video function and low power island, and extended the Hexagon architecture to support some new functions (such as video), while previous generations of Hexagons were mainly used to support audio functions. Hexagon has powerful development tools and is supported by more than 100 partners. At present, nearly 1000 partners plan to migrate CPU codes or functions to Hexagon in order to reduce power consumption.

Hexagon 680 integrates Hexagon Vector eXtensions:HVX) in DSP, which enables DSP to process a large amount of data simultaneously with one instruction. Combined with Spectra ISP in Qualcomm, this function can bring many differentiated functions, such as low-light video enhancement, which can improve performance by up to 3 times and save energy by up to 10 times. Proprietary low-power island and a set of infrastructure support sensor detection applications. Qualcomm's previous chips also have the function of supporting sensor sensing, but the new architecture can save up to 3 times of power. When the low power island is running, other parts of the chip can be turned off. We also introduced a set of sensor software solutions through DSP, which fully supported Android L.

Lens manufacturers will focus on lens modules with high pixels and low thickness.

As we said earlier, the principle of taking pictures of smart phones and professional cameras is basically the same, and the development goals are the same. Throughout the field of camera photography, high pixels are like jewels in the crown. Although many consumers have begun to accept the concept that high pixels do not represent high image quality. But high pixel is not a useless parameter. In short, high pixels can bring high-resolution effects and make photos more detailed and sharp. But at the same time, limited by the size of mobile phones, camera hardware suppliers led by Sony began to focus on photosensitive elements with more pixels in the same area at the end of 15.

In order to achieve more pixels in the same area, it is necessary to solve the problem of tail color interference between sub-pixels in dark light, which is what we often call photo noise. This requires improvement on the hardware level of photosensitive elements, such as ISOCELL, to distinguish sub-pixels from each other, or to improve the image quality by using software algorithms.