How to reduce the noise of mobile phone photos

Lead: Mobile phone photography has developed very fast in recent years, and taking photos casually has become something that everyone can easily do now. Although speaking of the professionalism in the field of photography, mobile phones are at best a drop in the bucket in front of SLR cameras, but mobile phones are better than wide penetration rates and can be carried around. Then, if you can only use the mobile phone as the most important daily life recording tool, you must first learn to overcome the interference of noise on image quality. If you just don't know much about noise, please follow the photographer's steps to analyze everything for you.

How to reduce the noise of mobile phone photography 1 Mobile photography: Noise is inevitable?

For many friends who just started shooting with their mobile phones, the shooting method is nothing more than turning on their mobile phones, starting the photo program, and then shooting. This traditional method is adopted in a sunny environment, which is very fast and easy to get the best results. But when you go indoors or come back to take pictures after sunset, you will start to feel a little tired. This kind of fatigue is mainly manifested in the huge delay when the screen of the mobile phone moves. What caused this?

The small size of mobile phone sensor is the main reason.

Facts have proved that even if the manufacturer claims to have achieved a large aperture of f/2.2 or even f/ 1.8, it is not enough for mobile phone sensors with only 1/3 inches. Xiao Di? The fact that it hurts badly. The light signal absorbed between units is limited, and all the details of the picture can be obtained instantly under the condition of sufficient ambient light during the day; In a dark environment, it needs to receive the same rich details, and it takes longer. If you switch from bright environment to dark environment at the same mobile phone speed, the mobile phone sensor will delay the picture due to insufficient light in dark environment. Once you stabilize the phone, you will find that the phone gradually begins to restore clear and bright images, even in a dark environment. Due to the limited area of the small sensor, even if it carries tens of millions of pixels, the unit pixel area is extremely small, and the recordable image details are very general.

How did the noise come about? Why do you always feel that the noise problem of mobile phones is much more serious than that of cameras? In photography, we know that the higher the ISO sensitivity, the worse the noise will be. ? Xiao Di? The reason is that we don't say it's a serious injury. In general, when shooting in automatic mode, in order to maximize the shutter speed, the sensitivity will be enhanced and the noise will be increased. On the premise of consistent exposure, we can only slow down the shutter speed if we want to reduce noise. However, if the shutter delay is slow, the hand-held shooting picture will be unclear. If you can only choose one, I guess you will choose the one with more noise and clear image!

Second, the way to reduce noise: soft and hard combination

If you accept it? Is this the only way to take pictures with a mobile phone? In fact, noise has no effect on you. In most cases, we just share a circle of friends, regardless of the magnification of 100%, and see how fine the picture quality is. When shooting, just hold it with both hands and press the shutter. But if you want to make the noise in the picture as little as possible and make the picture look better, here are two pre-and post-methods for your reference.

Method 1: Reduce exposure value. Every mobile phone reduces exposure in a different way. Take the iPhone as an example. Click on the focus, and then pull it down next to the little sun. The more you pull, the darker the whole picture becomes. Other Android phones can generally set exposure value in manual mode. The following is an example of the Bund.

Exposure value's renderings are undiminished.

As shown in the above figure, after opening the camera program of the mobile phone, the camera will take photos after global metering by default. When zooming in 100%, there will obviously be a lot of noise at the junction of light and dark. As the author mentioned above, after the camera program is started, the highest shutter speed is used by default to ensure that you get clear imaging. In night shooting, it is necessary to increase noise and improve ISO. If we want to have less noise and a purer picture, we can lower the exposure value to achieve the goal, as shown below.

After slightly lowering the exposure value, the overall picture is dark, but it is more attractive to the night view of the city. In automatic mode, the overall exposure is reduced, and of course the ISO value can also be reduced to achieve the purpose of noise reduction. But this method is by no means omnipotent. In the case that there are not many light sources in the picture itself (such as entering a dark room), even if the exposure is reduced, the noise cannot be reduced, as shown in the following figure.

Therefore, if you want to reduce noise by reducing exposure, the prerequisite is that at least the light source distribution area accounts for about 1/3 of the picture (such as night scene), which will be effective. If there is no light source, it will not only reduce the noise, but also make the whole picture extremely dim, which is really undesirable. Maybe you will ask, after reducing the exposure, the noise is reduced. Can you continue to improve the brightness through the later period? If you use a SLR camera, I can tell you that there is no problem at all. However, if you use a mobile phone, I suggest you give it up, because what you shoot with a mobile phone is a lossy JPG file, and you can't record the original data like the RAW format.

Add 1.35EV to the photo with the later software Adobe CameraRAW, and the exposure is the same as the original image. Although it seems that the details have increased slightly, the noise is very touching, which is equivalent to doing nothing.

If you pull back through ACR later, the details will be seriously lost (early left and late left)

Method 2: Manual gear+tripod. I believe this method is also the most familiar to everyone. All you need is a prop that can stabilize the mobile phone (portable tripod is recommended). After setting it, choose manual mode and set ISO to 100 to shoot. Shoot with a tripod, and the effect is immediate. 30100 can definitely guarantee the purest picture quality and the least noise under the current limited ambient light.

? The use of tripod is not omnipotent, especially for shooting moving objects. It is only suitable for still life or landscape photos. There are not many light sources. What if I want a moving object with pure picture quality? Well, then we can only use our ultimate killing method, PS post-processing. Photographers recommend two most commonly used methods here: the first one is to denoise by using the sharpening and noise reduction function of cameraRAW(ACR), and the second one is to denoise by using the PS plug-in Noiseware.

In the details tab of ACR, first sharpen the image, and all values should be increased. You can press alt to observe the effect of increasing the numerical size. The purpose of sharpening is actually to make the noise more obvious. After the noise appears, it can be removed by noise reduction function. Pay attention to the adjustment of brightness details. After the above operations are completed, denoising is completed.

As can be seen from the above figure, the noise reduction function of the later software is really powerful enough, and noise can be easily removed by dragging a few sliders. Sure enough, there is nothing PS can't do. If you think PS is still too professional to use, the last lazy artifact is the plug-in Noiseware. The plug-in can be downloaded, with a free trial period of 15 days, and friends who like it may wish to buy it for long-term use.

Lightroom mobile

In addition, since it is a mobile phone to take pictures, why can't there be software that the mobile phone can handle? Photographers here recommend Lightroom for iPhone/iPad, which is also easy to operate.

finally

At this point, you are already very clear about the front and back denoising in mobile phone photography, and it is estimated that it is only your own practice. Mobile phone photography always focuses on convenience. We can't bring a SLR or a single camera to the event at any time, but the mobile phone can really provide photo service all day. It is our goal and direction to do all aspects of mobile phone photography to the extreme. The pictures without noise are clean and beautiful. Try the method provided by the photographer as soon as possible!