Generally speaking, the current graphics (image) formats can be roughly divided into two categories: one is bitmap; the other is called drawing class, vector class or object-oriented graphics (image). The former describes graphics (images) in the form of lattices, and the latter describes graphics (images) composed of geometric elements mathematically. Generally speaking, the latter expresses images in a detailed and realistic manner, and the resolution of the graphics (images) after scaling remains unchanged, and is widely used in professional-level graphics (images).
Before introducing the graphics (image) format, it is necessary to understand some related technical indicators of graphics (images): resolution, number of colors, and grayscale of graphics.
Resolution: divided into screen resolution and output resolution, the former is expressed by the number of lines per inch, the larger the value, the better the quality of the graphics (image); the latter is the precision of the impulse output device, expressed by the number of pixels per inch;
Color number and graphic grayscale: expressed in bits, generally written as 2 to the nth power, where n represents the number of bits. When the graphics (image) reaches 24 bits, it can express 16.77 million colors, that is, true color. Grayscale representation class. Let’s learn about the current common graphic file formats one by one through the characteristic suffix name of the graphic file (that is, as shown in Figure .bmp): BMP, DIB, PCP, DIF, WMF, GIF, JPG, TIF, EPS, PSD, CDR, IFF, TGA, PCD, MPT.
BMP (bit map picture): the most commonly used bitmap format on PC has two forms, compressed and uncompressed. This format can express colors from 2-bit to 24-bit, and the resolution can also be from 480×320 to 1024×768. This format is quite stable in the Window environment and is widely used in occasions where the file size is not limited.
DIB (device independent bitmap): The ability to describe images is basically the same as that of BMP, and it can run on a variety of hardware platforms, but the file size is larger.
PCP (PC paintbrush): A compressed and disk space-saving PC bitmap format created by Zsoft, which can represent up to 24-bit graphics (images). There was a certain market in the past, but with the rise of JPEG, its status has gradually declined.
DIF (drawing interchange format): a graphic file in AutoCAD, which stores graphics in ASCII mode, and shows that the graphics are very accurate in size and can be edited by large software such as CorelDraw and 3Ds.
WMF (Windows metafile format): Microsoft windows metafile, which has the characteristics of short file and pattern modeling. Graphics of this type are crude and can only be edited in Microsoft Office.
GIF (graphics interchange format): A compressed graphics format that can be processed by various graphics processing software on various platforms. The disadvantage is that it can only store up to 256 colors.
JPG (joint photographic expert group): A graphic format that can greatly compress graphic files. For the same picture, the files stored in JPG format are 1/10-1/20 of other types of graphic files, and the number of colors can reach up to 24 bits, so it is widely used in homepages on the Internet or picture libraries on the Internet.
TIF (tagged image file format): The file size is huge, but the amount of stored information is also huge, and there are more subtle-level information, which is conducive to the reproduction of the tone and color of the original. The format has two forms, compressed and uncompressed, and the maximum number of supported colors can reach 16M.
EPS (encapsulated PostScript): An ASCII graphic file described in the PostScript language, which can print high-quality graphics (images) on a Postscript graphics printer, and can represent up to 32-bit graphics (images). The format is divided into Photoshop EPS format adobe illustrator EPS and standard EPS format, which can be divided into graphic format and image format.
PSD (Photoshop standard): The standard file format in Photoshop, a format optimized for toshop.
CDR (CorelDraw): The file format of CorelDraw. In addition, CDX is a graphics (image) file that can be used by all Coreldraw applications, and is a mature CDR file.
IF (image file format): It is used for large-scale super graphics processing platforms, such as AMIGA machines, and Hollywood special effects blockbusters are mostly processed in this IF format. Shape (image) effects, including color texture and other realistic reproduction of the original scene. Of course, the computer resources such as memory and external memory consumed by this format are also huge.
TGA (tagged graphic): It is a graphic file format developed by True vision for its display card at an earlier time, and the maximum color number can reach 32 bits. VDA, PIX, WIN, BPX, ICB, etc. belong to its collateral.
