I. BMP format
BMP is the abbreviation of English Bitmap, which is the standard image file format in Windows operating system and can be supported by many Windows applications. With the popularity of Windows operating system and the development of rich Windows applications, BMP bitmap format is naturally widely used. This format is characterized by rich image information and almost no compression, but this leads to its inherent defect-occupying too much disk space. So BMP is popular on stand-alone computers at present.
Second, the GIF format
GIF is the abbreviation of English graphic interchange format. As the name implies, this format is used to exchange pictures. Actually, it's the same. In 1980s, CompuServe, a famous online information service organization in the United States, developed this GIF image format for the limitation of network transmission bandwidth at that time.
GIF format is characterized by high compression ratio and less disk space, so this image format has been widely used soon. At first, GIF was only used to store a single still image (called GIF87a). Later, with the development of technology, several still images can be stored at the same time to form a continuous animation, which became one of the few formats that supported 2D animation at that time (called GIF89a). In GIF89a, you can specify a transparent area to make the image have an extraordinary display effect and make GIF more beautiful. At present, a large number of color animation files used on the internet are mostly files in this format, also known as GIF89a format files.
In addition, considering the actual situation in network transmission, the GIF image format also adds a gradual display mode, that is, in the process of image transmission, users can first see the general outline of the image, and then gradually see the details of the image as the transmission process continues, thus adapting to the user's viewing psychology of "from hazy to clear". At present, a large number of color animation files used on the Internet are mostly files in this format.
However, GIF has a small disadvantage, that is, it can't store pictures with more than 256 colors. Nevertheless, this format is still widely used on the Internet, which is inseparable from the advantages of short GIF image files, fast download speed and animation composed of many image files of the same size.
Third, JPEG format.
JPEG is also a common image format, which was developed by the Joint Photographic Experts Group and named as "ISO10918-1". JPEG is just a common name. The extension of JPEG files is. Jpg or. Jpeg, its compression technology is very advanced. It uses lossy compression to remove redundant image and color data, and can display very rich and vivid images at the same time, in other words, it can get better image quality with the least disk space.
At the same time, JPEG is a very flexible format, which has the function of adjusting the image quality, allowing you to compress this file with different compression ratios. For example, we can compress the BMP bitmap file of 1.37MB to 20.3KB at most. Of course, we can find a balance between image quality and file size.
JPEG is widely used because of its excellent quality and performance, especially on the Internet and CD-ROM. At present, all kinds of browsers support JPEG as an image format. Because of its small file size and fast download speed, the web page can provide a large number of beautiful images in a short download time, and JPEG has naturally become the most popular image format on the network.
Fourthly, JPEG2000 format.
JPEG 2000 is also formulated by JPEG organization, and its official name is "ISO 15444". Compared with JPEG, JPEG 2000 has higher compression rate and is a new generation of still image compression technology with more new functions.
As an upgraded version of JPEG, JPEG2000 has a compression ratio about 30% higher than JPEG. Unlike JPEG, JPEG2000 supports both lossy and lossless compression, while JPEG can only support lossy compression. Lossless compression is very useful for saving some important pictures. An extremely important feature of JPEG2000 is that it can realize progressive transmission, which is similar to the progressive display of GIF, that is, the outline of the image is transmitted first, and then the data is transmitted step by step, so as to continuously improve the image quality and make the image display from hazy to clear, instead of slowly displaying from top to bottom as JPEG does now.
In addition, JPEG2000 also supports the so-called "region of interest" function. You can arbitrarily specify the compression quality of the region of interest in the image, or you can choose to decompress the specified part first. Compared with JPEG, JPEG 2000 has obvious advantages and backward compatibility, and it is just around the corner to replace the traditional JPEG format.
JPEG2000 can be used in traditional JPEG market, such as scanners and digital cameras, and also in emerging fields, such as network transmission and wireless communication.
TIFF (Tag Image File Format) is a widely used image format in Mac. Developed jointly by Aldus and Microsoft, it was originally designed for cross-platform storage of scanned images. It is characterized by complex image format and much information stored. It is precisely because it stores a lot of subtle information of the image and the quality of the image is also improved, so it is very conducive to the reproduction of the original.
There are two forms of this format: compressed and uncompressed, in which compressed can be stored as LZW lossless compression scheme. However, due to the complex structure and poor compatibility of TIFF format, sometimes your software may not correctly identify TIFF files (most software has solved this problem now). At present, it is also very convenient to transplant TIFF files on Mac and PC, so TIFF is now one of the most widely used image file formats on microcomputers.
PSD format of intransitive verbs
This is a Photoshop document (PSD), which is a special format of Photoshop, the image processing software of the famous Adobe company. PSD is actually a "draft" of graphic design in Photoshop, which contains samples of various designs such as layers, channels and masks, so that the final design can be modified when the file is opened next time. Among the various image formats supported by Photoshop, PSD has much faster access speed and more powerful functions than other formats. With the wider application of Photoshop, we have reason to believe that this format will gradually become popular.
Seven. PNG format
PNG (Portable Network Graphics) is a new network image format. At the end of 1994, because Unysis announced that GIF had a patented compression method, the author of GIF software was required to pay a certain fee, which prompted the birth of free png image format. PNG combines the advantages of GIF and JPG from the beginning, and intends to replace these two formats in one fell swoop. 1 996 65438+1October1was proposed by PNG to the international network alliance and was recommended and recognized. Most drawing software and browsers began to support PNG image browsing. Since then, the PNG image format has been full of vitality.
PNG is the most undistorted format at present, which absorbs the advantages of GIF and JPG, has rich storage forms and has two color modes of GIF and JPG. Another feature of PNG is that it can compress image files to the limit of network transmission, but it can retain all information related to image quality, because PNG uses lossless compression to reduce file size, which is different from JPG sacrificing image quality for high compression rate. Its third feature is that the display speed is very fast. Downloading the image information of 1/64 can display a low-resolution preview image. Fourthly, PNG also supports the production of transparent images, which is very useful when making web images. We can set the image background to be transparent, and replace the transparent color with the color information of the webpage itself, so that the image and the webpage background can be harmoniously integrated.
The disadvantage of PNG is that it does not support animation application effects. If it can be strengthened in this respect, it can completely replace GIF and JPEG. The default format of Macromedia's Fireworks software is PNG. Now, more and more software is beginning to support this format, and the eighth and SWF formats are becoming more and more popular on the Internet.
With Flash, we can make an animation with the suffix SWF(Shockwave format), which can express rich multimedia forms in a relatively small volume. In image transmission, you don't have to wait until all files have been downloaded before you can watch them, but you can watch them while downloading them, so it is especially suitable for network transmission, especially when the transmission rate is not good, and you can get better results. Facts have also proved this point. SWF has been widely used in multimedia presentation and interactive design of web pages. In addition, SWF animation is made by vector technology, so no matter how many times the screen is enlarged, the screen will not be damaged. To sum up, the works in SWF format are favored by more and more web designers because of their high-definition image quality and compact size, and have become the mainstream of web animation and web picture design and production, and now they have become the de facto standard of network animation.
Nine, SVG format
SVG can be regarded as the hottest image file format at present. Its full English name is Scalable Vector Graphics, which means extensible vector graphics. It is based on XML (Extensible Markup Language) and developed by World Wide Web Consortium (W3C). Strictly speaking, it should be an open standard vector graphics language, which allows you to design exciting and high-resolution Web graphics pages. Users can draw images directly with codes, open SVG images with any word processing tools, and make the images interactive by modifying some codes, and they can be inserted into HTML at any time and viewed by browsers.
It provides the advantages that GIF and JPEG, the popular formats on the Internet, do not have: you can enlarge the graphic display at will, but never at the expense of image quality; Text remains editable and searchable in SVG images; Generally speaking, SVG files are much smaller than JPEG and GIF files, so the download speed is very fast. It is believed that the development of SVG will provide a new image standard for the Web. Other non-mainstream image formats:
1, PCX format
PCX format is a compressed format developed by ZSOFT when developing the image processing software Paintbrush, which occupies less disk space. Because this format has been around for a long time and has the ability of compression and full color, it is still popular now.
2.DXF format
DXF (Autodesk Graphic Interchange Format) is a vector file format in AutoCAD. It stores files in ASCII code, which is very accurate in representing the size of graphics. Many softwares support input and output in DXF format.
3.WMF format
WMF(Windows Metafile Format) is a common metafile format in Windows, which belongs to vector file format. It has the characteristics of short file and modeling mode, and the whole graph is often spliced by various independent components, and its graph is often rough.
4.EMF format
EMF(Enhanced Metafile) is a Windows 32-bit extended metafile format developed by Microsoft to make up for the shortage of using WMF. It also belongs to the vector file format, in order to make the metafile more acceptable. 5.LIC(FLI/FLC) format
Flic format was developed by Autodesk Company, and FLC is the collective name of FLC and FLI: FLI is an original animation file format based on 320×200 resolution, and FLC adopts a more efficient data compression technology, so the compression ratio is higher than FLI, and the resolution is also improved a lot.
6.EPS format
EPS(Encapsulated PostScript) is a format rarely seen by PC users, while users of Apple Mac computers use it more. It is an ASCII file format described in PostScript language, which is mainly used for typesetting, printing and other output work.
7.TGA format
TGA(Tagged Graphics) file is an image file format developed by American Truevision Company for its graphics card, which has been accepted by the international graphics and image industry. TGA has a simple structure, belongs to the general format of graphics and image data, has great influence in the field of multimedia, and is the preferred format for converting computer-generated images into TV.
At present, video formats can be divided into two categories: local video suitable for local play and network streaming video suitable for network play. It is worth mentioning that although the latter may not be as good as the former in terms of playback stability and playback quality, the wide spread of online streaming video makes it widely used in the fields of Internet information services such as video on demand, network demonstration, distance education and online video advertising.
I. Local video
●AVI format: its English full name is Audio Video Interleaved, that is, audio and video interleaved format. It was introduced by Microsoft in 1992, and is known and familiar with people together with Windows3. 1. The so-called "audio and video interleaving" means that video and audio can be intertwined and played simultaneously. The advantage of this video format is that it has good picture quality and can be used across multiple platforms. Its disadvantage is that it is too big, and what is worse is that the compression standard is not uniform. The most common phenomenon is that the high version of Windows media player can't play the video in AVI format edited in the early stage, and the low version of Windows media player can't play the video in AVI format edited in the latest stage. Therefore, when we play some videos in AVI format, there are often some puzzling problems. For example, the video can't be played because of the video coding problem, or even if it can be played, there are some puzzling problems, such as the inability to adjust the playback progress, and only sound without images when playing. If users encounter these problems when playing video in AVI format, they can solve them by downloading the corresponding decoder.
●nAVI format: nAVI is the abbreviation of newAVI, which is a new video format developed by an underground organization called ShadowRealm (it has little to do with the AVI format mentioned above). It is modified from Microsoft ASF compression algorithm, but it is different from the ASF video format in the network video introduced below. It greatly improves the definition of ASF video files by increasing the frame rate at the expense of the video "streaming" characteristics of the original ASF video files.
●DV-AVI format: The full English name of DV is Digital Video Format, which is a family digital video format jointly proposed by Sony, Panasonic, JVC and other manufacturers. At present, very popular digital cameras use this format to record video data. It can transmit video data to the computer through the IEEE 1394 port of the computer, and can also record the edited video data from the computer back to the digital camera. The file extension of this video format is usually. Avi, so it is also called DV-AVI format.
●MPEG format: Its full English name is Moving Picture Expert Group, that is, moving picture expert group format, which is the format of VCD, SVCD and DVD that people often watch at home. MPEG file format is the international standard of moving image compression algorithm. It uses lossy compression method to reduce redundant information in moving images. To put it more clearly, MPEG compression method is based on the fact that two adjacent images are mostly the same, and the redundant parts in the latter image and the previous image are removed, so as to achieve the purpose of compression (the maximum compression ratio can reach 200: 1). At present, there are three compression standards of MPEG format, namely MPEG- 1, MPEG-2 and MPEG-4. In addition, MPEG-7 and MPEG-2 1 are still in the research and development stage.
MPEG- 1: formulated in 1992, it is an international standard designed for digital storage media moving images and audio coding with data transmission rate below 1.5Mbps, which is also the VCD production format we usually see. Using the compression algorithm of MPEG- 1, a movie with the length of 120 minutes can be compressed to the size of1.2gb. The file extensions of this video format include. mpg，。 mlv，。 mpe，。 Mpeg and. Dat file in VCD.
MPEG-2: Based on 1994, the design goal is advanced industrial standard image quality and higher transmission rate. This format is mainly used for DVD/SVCD production (compression), as well as some HDTV (high definition television broadcasting) and some demanding video editing and processing. With the compression algorithm of MPEG-2, a movie with a length of 120 minutes can be compressed to a size of 4 to 8GB. The file extensions of this video format include. mpg，。 mpe，。 mpeg，。 M2v and. Vob file on DVD.
MPEG-4:MPEG-4 was established by 1998 and is specially designed for playing high-quality video of streaming media. It can compress and transmit data with extremely narrow bandwidth through frame reconstruction technology, and obtain the best image quality with the least data. At present, the most attractive feature of MPEG-4 is that it can save small-capacity video files close to DVD quality. In addition, this file format also contains some special functions, such as bit rate scalability, animation wizard, interactivity and even copyright protection, which are not available in previous MPEG compression standards. The file extensions of this video format include. asf，。 Mov and DivX AVI
Tip: Careful users must have noticed that there is no MPEG-3 coding in the middle. In fact, the familiar MP3 is MPEG-3 (MPEG layeur 3) coding.
●DivX format: This is another video coding (compression) standard derived from MPEG-4, commonly known as DVDrip format. It adopts MPEG-4 compression algorithm and integrates MPEG-4 and MP3 technologies. To put it bluntly, it is a video format formed by using DivX compression technology to compress the video image of DVD with high quality, compressing the audio with MP3 or AC3, and then combining the video and audio with the corresponding plug-in subtitle files. Its picture quality is almost the same as that of DVD, and its volume is only a fraction of that of DVD. This kind of coding has low requirements for machines, so DivX video coding technology can be said to be a new video compression format that poses the greatest threat to DVD, and it is called DVD killer or DVD terminator.
●MOV format: A video format developed by Apple. The default player is Apple's QuickTimePlayer. It has the characteristics of high compression ratio and perfect video definition, but its biggest feature is cross-platform, that is, it can support not only MacOS but also Windows series.
Second, the network video
●ASF format: its English full name is Advanced Streaming format, which is a video format launched by Microsoft to compete with the current Real Player. Users can play directly with Windows Media Player that comes with Windows. Because it uses MPEG-4 compression algorithm, the compression rate and image quality are very good (high compression rate is beneficial to the transmission of video stream, but the image quality will definitely be lost, so sometimes the image quality of ASF format is not as good as that of VCD).
●WMV format: Its full English name is Windows Media Video, which is also a file compression format introduced by Microsoft. It adopts independent coding mode and can directly watch video programs online in real time. The main advantages of WMV format include: local or network playback, extensible media types, component download, extensible media types, stream priority, multilingual support, environmental independence, rich inter-stream relationships and scalability.
●RM format: The audio and video compression standard developed by Real Networks Company is called Real Media. Users can use RealPlayer or RealOne Player to play network audio and video resources that meet the technical specifications of RealMedia. RealMedia can set different compression ratios according to different network transmission rates, so as to realize real-time transmission and playback of image data on low-rate networks. Another feature of this format is that users can use RealPlayer or RealOne Player to realize play online without downloading audio and video content. In addition, RM, as the mainstream network video format at present, can also convert videos in other formats into RM videos through its Real Server server, which is responsible for publishing and playing. RM and ASF formats can be said to have their own advantages. Generally, RM video is soft, while ASF video is relatively clear.
●RMVB format: This is a new video format, which is upgraded and expanded from RM video format. Its advantage lies in that the RMVB video format breaks the average compressed sampling mode of the original RM format, and makes reasonable use of the code rate resources on the basis of ensuring the average compression ratio, that is to say, static scenes with little action can leave more bandwidth space, and when there are fast-moving scenes, these bandwidths will be utilized. In this way, on the premise of ensuring the quality of still images, the image quality of moving images is greatly improved, thus achieving a delicate balance between image quality and file size. In addition, compared with DVDrip format, RMVB video also has obvious advantages. If a DVD movie of about 700MB is transcribed into RMVB format with the same audio-visual quality, its size will be about 400MB at most. Not only that, this video format also has the unique advantages of built-in subtitles and no plug-in support. If you want to play this video format, you can use RealOne Player2.0 or RealPlayer8.0 plus RealVideo9.0 or above.