Exif， This word is believed that many friends who are interested in photography have often heard or discussed it. What does Exif mean, how to view and get the data, and what is its purpose? Are the displayed parameters absolutely correct? Now let's understand it slowly.

Since Du Niang has already had a detailed explanation of the terms, we will not repeat it, but directly post it:

Exif is the abbreviation of the English Exchangeable Image File, originally formulated by the Japanese Electronic Industry Development Association (JEIDA). The current latest version is version 2.21 published in April 2002. The DCF -- Design role for Camera File system, which is being developed by the International Organization for Standardization (ISO), may be based on Exif2.1.

Exif file is actually a kind of JPEG file. It complies with the JPEG standard and only adds the content and index map of shooting information to the file header information. So you can use any image tool software that supports JPEG format to view or modify Exif files, but you may not see Exif information when you open it. Once you modify it, Exif information may be lost.

In brief, EXIF information is a series of information collected by digital camera during shooting, and then placed on the head of the well-known JPEG/TIFF file, that is, EXIF information is a group of shooting parameters embedded in the JPEG/TIFF image file format, mainly including aperture, shutter ISO、 Time and other information related to the photography conditions at that time, camera brand and model, color coding, sound recorded during shooting, global positioning system (GPS) and other information. In short, it is like the date printing function of a point and shoot camera, but the EXIF information records more detailed and complete information.

(The above paragraph is taken from Baidu Encyclopedia)

OK, after a brief understanding of Exif, how can we obtain these data in daily use?

If your shooting device is a mobile phone, we can directly open the sample you need to view in the mobile phone album, click the details to see the Exif of the sample in more detail. Usually we pay more attention to the manufacturer, aperture ISO、 Shutter speed. Note that the focal length here is not equivalent to 35mm focal length, but only the focal length corresponding to this sensor.

What's the use of obtaining the data of these samples? Maybe these data are really meaningless for ordinary users. However, small editors often compare the performance of samples under different parameters, so these parameters become important comparison data.

If you have seen the shooting evaluation articles written by Xiao Bian, you will often see that Xiao Bian will print the Exif information of each sample in the lower right corner of the photo, so that you can distinguish the samples to be compared, and also compare the samples taken by two hand-operated machines under the same or similar shooting parameters.

In addition, when you see a beautiful picture on the network, you can query the relevant Exif information through some methods, and also know what machine was used to take the picture, ISO、 If you adjust the shutter speed and aperture, you can take such pictures and other information.

However, using HDR and night view modes in some mobile phones may cause their Exif to be lost. This is because some mobile phones will modify the sample after using these modes, which may be processing such as smearing noise, improving brightness, and reducing shadows. This will change the original sample data, thus losing Exif information. For example, the above two pictures were taken by Samsung Note 3 Neo and used HDR mode. Since Samsung HDR mode can choose to keep the original picture, the small editor will keep it first. However, Samsung HDR and night view mode will process the samples, so the samples taken in these two modes cannot be found Exif.

The most common and convenient one is to import it into the computer to view it. We can view the Exif information of this sample in detail by opening the corresponding photo folder on the computer, right clicking the properties, and selecting the details column. In this way, the sample is taken in full manual mode using Lumia 1020.

Of course, some samples still cannot see Exif information in this way. At this time, we can reveal this information through other image viewing software.

For example, software such as "X-ray image viewing" does not display Exif information by default. We can view the Exif of this photo by pressing F12 on the keyboard.

Although it is easy to view the Exif of the sample by right clicking the property of the sample, the Exif can also be easily changed, including the camera model and ISO. If you want to cheat you with some fake samples, you can cheat you by directly changing the model.

The changed information is also retained as valid information. For example, for this sample taken by Lumia 1020, we changed the camera model to Lumia 1990 (this model does not exist) in the attribute details. After saving, Exif will show that this sample is from Lumia 1990 (pay attention to Exif in the lower right corner of the sample).

Sometimes, in order to get better publicity, some mobile phone manufacturers even use some samples taken by high-end SLRs or digital cameras to pretend to be samples taken by mobile phones.

The recent classic case of falsification of samples is the previous samples taken by the subsidiary brand IUNI U2 of Jinli. At that time, the official announced that these samples were all real samples taken by IUNI U2, but the temporary workers were not able to do their best, and the Exif information was not changed when the original picture was released, which eventually led to the Exif of the sample being viewed by the eye-catching netizens, It was originally taken by Shima camera, not U2. From Exif here, we can see that the aperture of this photo is 10, the shutter speed is 1/200 second, and the ISO is 100. It was taken on September 13, 2008. So if you know how to view Exif information, you can know whether these samples are real or not.

In addition, in fact, many mobile phone manufacturers have such cases of false propaganda. For example, Nokia has previously publicized the optical anti shake function of its Lumia mobile phone and other demonstration videos, which were finally found to be actually shot using SLR and anti shake head.

Recently, there is a big controversy, including the sample of the Hammer mobile phone. This sample is really good, with little noise, very clean, but a little heavy sense of smearing. However, for the hammer evaluation machine available to the media at present, it seems that it has not achieved such effect. It is generally reflected that the performance is good in the daytime, but it is not so good at night, which is far from the effect of the propaganda sample. Of course, it can also be inferred that the engineering machine has not been optimized well enough, but if not, how can these beautiful samples be shot? We won't have to make more guesses.

It was said that it was questioned mainly because the Exif information of these samples at that time contained traces that were suspected to have been modified by ACDSee Pro 6. But just such a small detail has attracted many suspicions.

So Lao Luo also published a long microblog for this matter (screenshot shows the content of the long microblog), claiming that it was deliberately made by the brothers in the camera department to confuse the public. Of course, this is what Lao Luo said on his microblog. As for whether you believe it or not... it's up to you.

However, you may think that the Exif of these samples is so normal that they should be real samples, right? In fact, whether this is a true proof is not really unknown to the party concerned, and even Lao Luo may be kept in the dark.

In fact, in addition to the above simple change of Exif information through attributes, some professional software can also be used to modify Exif information. This type of software can basically change all Exif information. For example, this picture taken by Lumia 1020 does not even have lens focus information in the changeable information.

But through this software, we can add the information we need in this software, and the values are filled in as we like. For example, Xiao Bian set the focal length of this sample to 35mm (in fact, the focal length of a mobile phone camera is not that long) and saved it.

We can also see that the focal length information of this sample is indeed changed to 35mm as we just modified it. In this way, you can also change a very beautiful and attractive sample taken by an SLR or high-end digital camera to a more reliable parameter related to the mobile camera, which can be very clever.

So before the real machine is available, the real machine shooting samples promoted by any manufacturer can be regarded as a joke to achieve the publicity effect. True or false, if you are willing to make false propaganda, how can you find evidence so easily (except for IUNI). If you are a conscientious manufacturer, you may really dare to use real samples for publicity, but the fact proves that there are not many such manufacturers, or they are both true and false, and what you see may not be true. You must experience it in person and make a conclusion after verification. If the real machine is available and the effect can still reach the level of propaganda, then take your beliefs to preach. But before that, please calm down.

Why be so serious about a sample? The reason why Xiao Bian competes with others is not because of feelings, but because he likes to be serious. After you see that the Exif of the sample can be changed so easily, will you still believe the "real sample" issued by the manufacturer?