What is EXIF

Xif is an English exchangeable Image
The abbreviation of file (interchangeable image files) was initially developed by the Japanese electronics Industry Development Association (jeida)
-- Japan Electronic Industry Development Association)
Developed, the latest version is 2.21
. DCF-design
Role for camera file system) may be based on exif2.1.

EXIF
A file is actually a type of JPEG file. It complies with the JPEG standard, but adds the content and index of the shooting information to the file header information. Therefore, you can use any image tool software that supports JPEG format to view or modify EXIF files. However, EXIF information may not be displayed when you open the file. Once modified, EXIF information may be lost.

In short, EXIF
Information is a series of information collected by a digital camera during the shooting process, and then stored in the well-known information
The header of the JPEG/TIFF file, that is, the EXIF information is embedded in JPEG/tiff.
A set of shooting parameters in the image file format, including the aperture, shutter, ISO, date and time of photography and other information related to the photography conditions at that time, camera brand model, color encoding, the recorded sound and GPS information during shooting. Simply put, it is like the date printing function of a dummies camera,
EXIF information records more detailed and complete information.
Exif21.pdf (580 K) official EXIF 2.1 standard set by jeida. (1998.6.12)
Exif22.pdf (750 k) official EXIF 2.2 standard set by jeida. (2002.4)
Exif file format
For more information, see the English document.
EXIF ID

All JPEG files start with the string "0xffd8" and end with the string "0xffd9. The file header contains a series of "0xff ??" A string in the format of "identifier ",
Used to mark the information segment of a jpeg file. "0xffd8" indicates that the image information starts, and "0xffd9" indicates that the image information ends. The two identifiers do not have any information, while other identifiers keep up with some information.
Character.

0xffe0 --
The identifier between 0xffef is called the "Application tag" and is not used by common JPEG files. EXIF records the shooting information such as the shutter speed and aperture value by using this information string. It can even include
Ball positioning information. According to the definition of these identifiers according to exif2.1 standards, digital cameras can record all kinds of shooting information into digital images, applications can read the data, and then follow the exif2.1 Standard
Accuracy:

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 resolution
This topic already has special entries 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 exposure Program
Specifies the setting of procedural Automatic Exposure. Different cameras may be Sutter.
Priority (shutter priority), aperture priority (shutter priority) 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 focal length equivalent to 35mm of the camera.
Makernote (User comment) author Mark, description, record
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 universal extended item definition pointer
It is related to the TIFF file. The specific meaning is unknown.
The compression ratio of the filesource File compression.