Meta data (MetaData)

Metadata is the data that is used to describe the data (that is, describes other). It's not a good idea to say this alone, but let me give you an example.

The following is a section of Chekhov's novel, "A Man in the set," depicting a woman named Lotus card:

age is not light, 30-year-old, tall, tall, shapely, black eyebrows, red face--a word, not a girl, but jelly, she was so active, noisy, constantly humming a little Russian lyric songs, loud laughter, and then issued a series of loud laughter: ha, ha, ha!

This passage provides the following information: Age (30 years old), height (tall), appearance (shapely, black eyebrows, red face), character (lively, noisy, constantly humming small Russian lyric songs, Loud laughter). With this information, we can imagine what kind of person a Lotus card is. By the way, we can also extrapolate the look of other people as long as we provide these kinds of information.

The "Age", "height", "look", and "character" in this example are metadata, as they are data/information used to describe specific data/information.

Of course, these meta-data are not accurate enough to portray a personal situation. Each of us from small to large, have filled out the "Personal Status registration form" and other things, including name, gender, ethnicity, political appearance, one-inch photos, education, title and so on ... This set of meta-data is fairly complete.

In daily life, meta data is ubiquitous. A class of things, you can define a set of meta-data.

Friends who like to take digital photos should know that each digital photo contains EXIF information. It is a meta-data used to describe digital images. In accordance with the EXIF 2.1 standard, which mainly contains such information:

Image Description Description, source. Refers to the tool that generates the image

Artist author Some cameras can enter the user's name

Make producer refers to the product manufacturer

Model model refers to the type of equipment

Orientation direction of some camera support, and some do not support xresolution/yresolution x/Y direction Resolution This column has a special article to explain this issue.

Resolutionunit resolution units are typically PPI software software displays firmware firmware version datetime date and time

Ycbcrpositioning Hue locates the Exifoffsetexif information location, defines the EXIF write in the file, and some software does not display. Exposuretime exposure time is the shutter speed fnumber aperture factor Exposureprogram Exposure program refers to the setting of program AE, each camera is different, may be Sutter priority (shutter first), aperture Priority (shutter first) and so on.

ISO Speed Ratings Sensitivity

Exifversionexif version

Datetimeoriginal creation Time

Datetimedigitized Digital Time

Componentsconfiguration Image Construction (multi-finger color combination scheme)

Compressedbitsperpixel (BPP) compression per pixel color position refers to the degree of compression

Exposurebiasvalue exposure compensation.

Maxaperturevalue Maximum aperture

Meteringmode metering method, average metering, center-weighted metering, spot metering, etc.

LightSource light source refers to the white balance setting whether Flash uses Flash.

Focallength focal length, generally showing the lens physical focal length, some software can define a coefficient, thus showing the equivalent of 35mm camera focal length Makernote (User Comment) author tag, description, record Flashpixversionflashpix version (individual models supported) ColorSpace color gamut, color space exifimagewidth (Pixel X Dimension) image width refers to the number of landscape pixels

Exifimagelength (Pixel Y Dimension) Image height refers to the number of longitudinal pixels interoperability IFD commonality extension definition pointers and TIFF file related, unspecified

Filesource source file compression compression ratio.

Let me cite one more example. You can find information about each movie in the Movie Database IMDb. The IMDB itself also defines a set of metadata that is used to describe each movie. Here is its first-level metadata, each level below is also listed two levels of metadata, combined together, can be described in more than 100 aspects of a movie:

cast and Crew (cast), company Credits (Related companies), Basic Data (Basic), Plot & Quotes (plots and quotations), fun Stuff (interesting information), Links to other Sites (external link), Box Office and Business (office box and commercial development), Technical info (technical information), literature (written content), other data (additional information).

The greatest benefit of metadata is that it enables the description and categorization of information to be formatted, thus creating the possibility for machine processing.

Finish

Original address: http://www.ruanyifeng.com/blog/2007/03/metadata.html

Meta data (MetaData)