I. 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 gradual 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 applied to the traditional JPEG market, such as scanners, digital cameras, and other emerging fields, such as network transmission and wireless communication.
Second, TIFF format
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 store 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.
Thirdly, PSD format.
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.
Four. 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 promoted 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 begin to support this format, and it is becoming more and more popular on the Internet.
Verb (abbreviation for verb) SWF format
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.
SVG format of intransitive verb
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, which aims to make the metafile more acceptable.
5.LIC(FLI/FLC) format
Flic format was developed by Autodesk company. FLIC is a general term for FLC and FLI: FLI is an original animation file format based on 320×200 resolution, while FLC adopts a higher resolution. Although the compression ratio of LI is higher, its resolution has been 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.
Introduction to common picture formats
BMP (Window Standard Bitmap) is one of the most common bitmap formats, and it is also the standard format under the window system. It is a file that saves the bitmap displayed under the window in a lossless form. Its advantage is that it will not reduce the picture quality, but the file size is relatively large.
JPG/JPEG (Joint Graphics Expert Group Picture Format) is most suitable for true color or smooth transition photos and pictures. This format uses lossy compression to reduce the size of the picture, so users will see that the quality of the picture will decrease as the file shrinks. When a picture is converted to a. jpg file, the transparent areas in the picture will be converted to solid colors.
PNG (Portable Network Graphics Format) is suitable for any type of picture with any color depth. You can also use PNG to save pictures with color palettes. This format uses lossless compression to reduce the size of the picture, while retaining the transparent areas in the picture, so the file is slightly larger. Although this format is suitable for all pictures, some Web browsers do not support it.
GIF (Graphic Interchange Format) is most suitable for line drawing clip art (for example, up to 256 colors) and large solid color pictures. This format uses lossless compression to reduce the size of the picture. When the user wants to save the picture as. GIF, they can decide whether to save the transparent area or convert it to solid color. At the same time, through the conversion of multiple pictures, GIF format can also save animation files. However, it should be noted that GIF can only support 256 colors at most.
At present, there are two image compression formats widely used on web pages: gif and JPG. Because of their fast loading speed on the Internet, all newer image software supports GIF and JPG formats. Therefore, if you want to create a GIF or JPG image, you only need to save the image in these two formats in the image software.
But which is better, GIF or JPEG? The answer is that it depends on the graphics. Need to consider the size and download speed of graphics.
One of your basic considerations is the type of graphics you use. If the graphics use multiple colors, especially when different colors cross each other, it is best to use JPEG format. If the color of the graphic used is simple, it should be in GIF format.
Multicolor graphics are in JPEG format because JPEG can save millions of colors, while GIF is limited to 256 colors. Another important issue is the size of the file. JPEG allows greater compression ratio. GIF has a smaller compression ratio. For larger graphics, JPEG should be used. JPEG can almost keep the original appearance of graphics.
GIF can do things that JPEG can't. For example, you can stagger GIFs. Interlaced GIF graphics can be downloaded with low definition first, and then gradually clear. In this way, readers can quickly see what this number is at first. JPEG, on the other hand, is an intelligent line-by-line download, and you can only see the whole picture by downloading the whole picture.