Common picture formats

1. JPEG: Joint photo Expert Group (JPRG, Joint Photographic Expert Group) file suffix named ". jpg" or ". JPEG "
Features: lossy compression format, it is possible to compress the file to the smallest format
Use: For the internet, reduce image transmission time, for graphics that require continuous tone, is the most popular image format on the network today
Advantages: 1, photographic works or realistic works support advanced Compression 2, the use of variable compression ratio can control file size
3, support interleaving (for the asymptotic type JPEG file) 4, JPEG widely supports Internet standards.
Disadvantage: 1, lossy compression will reduce the quality of the original image data. 2, editing and re-saving will be mixed with the original image of the quality of data decline, this decline is cumulative.
3. JPEG is not suitable for simple pictures with very few colors, similar areas with large blocks, or very noticeable differences in brightness.

2. gif: Graphics Interchange Format (GIF, Graphics Interchange Format)
Features: Lossless compression format for continuous tones based on the LZW algorithm.
Use: Network dynamic diagram widely used
Advantages: 1, almost all relevant software support it, the public domain has a large number of software in the use of GIF image files
2, depth from 1bit to 8bit, that is, up to 2 of the 8 256 colors of the image
3, GIF files can be stored in a number of color images 4, GIF decoding faster, because the use of each row of GIF image 5, small size, relatively clear imaging
Cons: 1, GIF does not support alpha transparent channel

3. PNG: (Portable Network Graphics) portable Web graphic
Features: Supports high-level lossless compression.
Use: Attempt to replace GIF and TIFF file formats
Advantages: 1, support high-level lossless compression. 2, support alpha channel transparency. 3, support gamma correction. Support Interleaving. 4. Supported by the latest WEB browsers.
Cons: 1, older browsers and programs may not support PNG files. 2, with the JPEG lossy compression compared to less compression.
3, for multi-image files or animation files do not provide any support like GIF.

4. SVG: (Scalable Vector Graphics)
Features: Can be scaled in the case of image quality without degradation, based on XML developed by the World Wide Web Consortium, is an open standard vector graphics language
Use: Make maps (scalable, text searchable, optional), dynamic interactive images (respond to user actions such as highlighting, sounds, effects, animations, etc.), inline with XML documents, etc.
Advantages: 1, can be read and modified (such as Notepad), smaller size, and more compressible. 2, scalable, standard open. High-quality printing at any resolution
3, the text in the image can be selected, searchable. 4. File is pure XML, support DOM, such as <svg></svg>

5, PSD: (photoshopdocument) Photoshop image processing software dedicated file format
Feature: is a non-compressed original file save format, large capacity, but can retain the image of all the original information
Use: Save images in PhotoShop software all original information used

6. ICON:
Features: Icon is a form of icons for system icons, software icons, etc., this icon extension is *.icon, *.ico
Use: Small images, small icons, etc.

7, BMP: Bitmap (BMP, BitMaP)
Features: Hardware device independent, compression not supported, standard image file format in Windows operating system
Use: Windows system wallpaper, etc.
Pros: BMP supports 1-bit to 24-bit color depth. BMP format is widely compatible with existing Windows programs (especially older programs)
Disadvantage: BMP files occupy a large amount of space
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Image depth refers to the number of bits that are used to store each pixel, and also to measure the color resolution of the image.
Like a monochrome image, if each pixel has 8 bits, the maximum number of shades is 2 8, or 256.
such as: the size of a picture is 1024x768, the depth of 16, then its data volume is 1.5M
Calculation: 1024*768*16 (Bit)/8 (Byte) =1.57m
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8. tif: Tagged Image File Format (TIF, TIFF, Tagimage FileFormat)
Features: Image file format is the format for recording and storing image information. To store, process and propagate digital images, a certain image format must be used.
That is, the pixels of the image are organized and stored in a certain way, and the image data is stored as a file to get the image file. Image File Format
Determines what type of information should be stored in the file, how the file is compatible with various application software, and how the file exchanges data with other files.

9. Tag: Tagged graphics (Tagged graphics)
Features: A preferred format for computer-generated image-to-TV conversion, supports compression, and uses an undistorted compression algorithm
Advantages: The most important feature of TGA image format is the ability to make irregular shape graphics, image files

Common picture formats