What is the graphic format that can produce animation effects in web page files?

In web page files, the graphics format that can produce animation effects is the gif format; the full name of gif is "Graphics Interchange Format", which is the graphics exchange format, used to display indexed color images in hypertext markup language. gif uses the "Lempel-Zev-Welch" compression algorithm and supports up to 256 colors.

The operating environment of this tutorial: Windows 10 system, DELL G3 computer.

In web page files, the graphics format that can produce animation effects is GIF

The full name of GIF is Graphics Interchange Format, which can be translated as Graphics Interchange Format, used to use Hypertext Markup Language (Hypertext Markup Language) Markup Language) method to display indexed color images, which is widely used on the Internet and other online service systems. GIF is a public image file format standard, the copyright of which belongs to Compu Serve.

The name of the GIF format is the abbreviation of Graphics Interchange Format. It was developed by Compu Serve in 1987 to fill the gap in cross-platform image formats. GIF can be supported on multiple platforms such as PC and Macintosh.

GIF is a bitmap. The general principle of bitmap is: a picture is composed of many pixels, each pixel is assigned a color, and these pixels are combined to form a picture. GIF uses the Lempel-Zev-Welch (LZW) compression algorithm and supports up to 256 colors. Due to this characteristic, GIF is more suitable for pictures with less color, such as cartoon shapes, company logos, etc. If you encounter situations where true colors are needed, the expressive power of GIF will be limited. GIF usually comes with a palette that stores the various colors that need to be used. In web applications, the file size of images will obviously affect the download speed. Therefore, we can optimize the palette according to the characteristics of GIF with palette and reduce the number of colors used in the image (some images cannot use it. colors can be dropped) without affecting the quality of the picture.

The biggest difference between the GIF format and other image formats is that it is completely designed as a public standard. Due to the popularity of the Compu Serve network, many platforms support the GIF format. Compu Serve promotes GIF by distributing format instructions for free, but requires software that uses the GIF file format to include a description of its copyright information.

The image file structure in GIF format is as shown in the figure.

(1) The file header is a data block with a data stream identifying the GIF format to distinguish earlier versions from new versions.

(2) The logical screen description area defines the image plane size and color depth related to the image data, and indicates whether the subsequent palette data area belongs to the global palette or the local palette. If a global palette is used, a 24-bit RGB global palette is generated, in which one primary color occupies one byte.

(3) Palette data area. Divided into general palette and local palette. The general palette is suitable for all images in the file, and the local palette is only suitable for a certain image.

(4) There are two types of content in the image data area, one is pure image data, and the other is data blocks for special purposes (including special application code and non-printable annotation information). In GIF89a format image files, if a file contains multiple images, the image data area will repeat the sequence of data blocks in sequence.

(5) The end flag area is mainly used to mark the end of the entire data flow.

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