A mobile phone that has a camera function close to a part of our body. As such an important tool, in addition to some daily scanning codes, the most important thing is to take pictures. When we go out to travel, we will shoot, daily interesting will shoot, after a week of smog lifting the blue sky we will shoot, after the rain we will also shoot the rainbow, it has assumed an indispensable part of life function. This is why after the release of each mobile phone, in addition to the processor, battery, system, everyone is also very concerned about the camera. And when it comes to taking pictures, a headache is the night shooting ability of the mobile phone, either too much noise or black into a mess can not see clearly, there is another problem that can not be escaped - excessive explosion. Especially at night, when we want to try to shoot a street scene, after shooting, we find that the street lights and signs are overexposed, and the paste is a mess, which greatly affects the picture effect.
For example, the above one, I shot in the North Sea, the effect is very unsatisfactory, the problem of overburdening of the light is very serious, I wanted to take a beautiful night scene to put in the circle of friends, but this effect made me immediately dispel the idea.
But in addition to the overexposure of the entity itself, we carefully look at the sky will appear a "ghost", that is, the shadow reflected by the entity, which we call "glare", if not specifically to shoot the "ghost shadow", the appearance of this patch of light is also very influential. Let's analyze these two phenomena.
Local overexposure
First of all, let's talk about local overexposure, overexposure is due to the light difference of the object in the shooting screen caused by the local overexposure of the situation, generally we shoot the object, encounter the situation that the difference in light is too large, if you want to adjust the screen exposure, you can only reduce or improve the overall exposure of the picture, it is impossible to dim the place where the light is strong and the light is not enough to maintain the original exposure. We can only satisfy one of them, and the other needs to give sufficient conditions for the early or late stage to achieve the goal. This all depends on the tolerance of the camera sensor, which refers to the ability of the photosensitive material to correctly record the brightness range of the scene in proportion, that is, the difference between the brightest part and the darkest part of the surface of the subject being photographed. Night scene has always been a pain point for mobile phone photography, because the current sensor tolerance can not cover the dark night and the glowing lights together, which has led to the problem of local overexposure.
As just said, if you want to solve the problem of local overexposure in imaging, you can only achieve it through the early and post stages, and the camera itself cannot solve it. In the early stage, you can use the flash, that is, to increase the brightness of the shadows in the picture, so that there will be no local overexposure problems when adjusting the overall exposure, or direct post-adjustment. As a mobile phone manufacturer, you can only improve the night shooting effect through these two methods, such as adding flash to the mobile phone. But the flash is limited to shooting relatively close objects, if you want to shoot a relatively distant night scene, the flash of the mobile phone will not work, then it can only be solved through post-production. In response to this problem, mobile phone manufacturers began to add night mode, through the HDR algorithm to reflect the image of the best details corresponding to the exposure time, so as to achieve the best effect of a bright detail that is not exposed, and the dark details are also clearly displayed. For example, the Handheld Super Night Mode updated by Xiaomi Mi 8 and the Night Mode of the vivo NEX Dual Screen Version are handled very well in this regard.
The above is a sample taken with handheld night mode after the Xiaomi Mi 8 upgrade, which has been greatly improved. Taking the vivo NEX dual-screen version as an example, it will perform multi-frame synthesis of 12-16 frames when shooting night scenes, and improve the tolerance of the picture through algorithms. Let the night scene shooting no longer be a bright and mushy mess.
Ghost
The next thing to talk about is the "ghost" that has just appeared, which is a situation in the glare. What is glare? How did it happen?
All lenses are affected by certain non-ideal factors in the process of transmitting images, which cause aberration caused by light error deflection, which is glare. If such a phenomenon occurs, it does not mean that the mobile phone camera is broken or the hardware equipment is too poor, because this is due to the physical nature of the lens itself, and even the SLR lens cannot be avoided. The lens of the mobile phone is not a single piece of glass, but is composed of multiple layers of lenses.
In simple terms, you can paint the camera composition of the mobile phone as above, the lens is generally represented by P or G, which depends on the material of the lens, generally plastic material and glass material (resin), plastic referred to as P (plastic), glass referred to as G (glass), we often see many mobile phone manufacturers at the conference to declare that the mobile phone uses 6P lens is to say this. Plastic lens cost is low, the light transmission effect is not as good as glass, some manufacturers will take a combination of the two, such as 2G3P is two glass lenses and three plastic lenses combined. In general, the more lenses, the better the light gathering effect of the camera, but you can not simply pursue the number of lenses, the number of more thickness not only increases the penetration of the light, but also increases the thickness of the fuselage.
The glare problem that occurs in our mobile phones is due to the light passing through the glass cover, and then through the lens, infrared filter to reach the sensor, so it will produce an internal reflection and re-reflection between these layers, and the final presentation will present this deviation. The "ghost" we see is due to the reflection between the two after the light passes through the cover glass to the lens, and what we see is formed by the reflection of the cover glass.
This solution is usually to coat the lens, reduce reflection and improve the lens transmittance. If you want to make the "ghost" less, you can choose a glass lens with a higher cost and better light transmittance. We can also try to change the shooting angle when we shoot ourselves, but due to the physical reasons of the lens itself, the "ghost" cannot be removed, and can only be solved later.
There is also a type of glare that is the reflection of light formed between the lens and the lens.
Take a look at the picture below.
In the middle is a brighter "ghost", and there are several layers of halos outside the ghost, which is caused by the reflection between the lens and the lens. If you count carefully, you can see that the phone that took this photo uses a 6P lens.
There is also a kind of glare, according to the different angles of light into the light, the coating will also produce different degrees of offset, forming a red light. In order to ensure that the final imaging does not appear to be red light caused by shifts, many camera manufacturers will choose to use blue glass filters as a method of filtering infrared rays.
The above is why the mobile phone will appear glare principle analysis, simple summary, if you want to avoid glare, one is coated on the lens, the other is simply to choose a lens module with better materials, good lens material good coating technology, directly through the hardware to improve. Finally, a summary of the local overexposure and glare that appears in the mobile phone photo, if you want to take a good photo, buy a good mobile phone! Hardware and algorithms are awesome phones.