Metadata (metadata)

I feel that metadata is always vague and there is no clear concept. Here is a simple arrangement.

Definition of Wikipedia everyone on Earth knows that metadata is the data used to describe data attributes. It is used to support functions such as storage locations, historical data, resource searches, and file records.

But what is data that describes data? Instead, the metadata concept is more abstract. Here is an image example:

In the graduation season, everyone is looking for a job. They need to fill in their resumes to find a job. What do I have on my resume? Name, gender, ethnicity, political outlook, local place, education background, project experience, internship experience, and blab. Of course, each person's information is different, but through such a characterization, the company's HR can quickly have a systematic understanding of a person. Your specific age (26), specific gender (male), specific nationality (Han nationality) and other specific information constitute your personal information, the name, age, gender, and so on are descriptions of specific information such as you are 26 years old, male, and Han nationality. Because the resume template is actually a set of metadata.

In fact, you can make a very simple distinction, No matter what system, there will be a variety of data. What we need to do is to strip the specific information, and the rest is the metadata.

For example, what is left after the specific information stored in the data table is removed? Table module. These are metadata.

In the database system, what is left besides the specific information? Database IP address, port, dialect, and other configuration information, as well as the modules of each database.

Here are some examples of life:

Friends who like to take digital photos should know that each digital photo contains EXIF information. It is a metadata used to describe digital images. According to the EXIF 2.1 standard, this includes the following information:

Image Description: Image Description and source. It refers to the image generation tool.
Artist author some cameras can enter users' names
Make producer refers to the product manufacturer
Model indicates the device model.
Orientation supports some cameras, and some do not.
Xresolution/yresolution x/y direction resolution this topic already has a special item to explain this problem.
Resolutionunit resolution unit is generally PPI
The software displays the firmware version.
Datetime Date and Time
Ycbcrpositioning color phase Positioning
Exifoffsetexif information location, defines the write of EXIF information in the file, some software does not show.
Exposuretime: shutter speed
Fnumber aperture Coefficient
Exposureprogram specifies the program-based Automatic exposure settings. Different cameras may have Suter priority (SHUTTER first), aperture priority (SHUTTER first), and so on.
ISO speed ratings sensitivity
Exifversionexif version
Datetimeoriginal Creation Time
Datetimedigitized digitization time
Componentsconfiguration Image Construction (Multi-finger color combination solution)
Compressedbitsperpixel (BPP) indicates the degree of compression of each pixel color bit.
Exposurebiasvalue exposure compensation.
Maxaperturevalue maximum aperture
Meteringmode: Average, central, and point.
Lightsource light source refers to white balance settings
Whether or not Flash is used.
Focallength focal length. Generally, the physical focal length of the lens is displayed. Some software can define a coefficient to display the author Mark, description, and record of the makernote (User comment) equivalent to the focal length of 35mm cameras.
Flashpixversionflashpix version (supported by some models)
Colorspace Color Gamut and Color Space
Exifimagewidth (pixel x dimension) Image Width refers to the number of horizontal dimensions
Exifimagelength (pixel y dimension) Image Height refers to the number of vertical dimensions
Interoperability IFD generic extended item definition pointer is related to the TIFF file, the specific meaning is unknown
The compression ratio of the filesource File compression.

Let me give another example. You can find information about each movie in the Movie Database IMDB. IMDB also defines a set of metadata to describe each movie. Below is its level-1 metadata. The level-2 metadata is listed below each level. In total, a movie can be characterized from over 100 aspects:

Cast and crew, company credits, basic data, plot & quotes, and fun stuff) links to other sites (external links), box office and business (box office and commercial development), Technical Info (technical information), literature (written content) and other data (other information ).

The biggest benefit of metadata is that it allows the description and classification of information to be formatted, which creates a possibility for machine processing.

References:

Wikipedia-http://zh.wikipedia.org/wiki/%E5%85%83%E6%95%B0%E6%8D% AE

Http://www.ruanyifeng.com/blog/2007/03/metadata.html

Metadata (metadata)