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This article mainly introduces what picture formats are on the web web page, the article is very detailed, has a certain reference value, interested friends must read it!

Features of GIF format:

Transparency

Gif is a type of Boolean transparency, which can be either fully transparent or completely opaque, but it is not translucent (alpha transparent).

Animation

The format Gif supports animation.

Lossless property

Gif is a lossless image format, which means that you can do anything with gif images without compromising image quality.

Horizontal scanning

Gif is compressed using an algorithm called LZW. When compressing gif, pixels are compressed horizontally from top to bottom, which also means that horizontal gif images are smaller than vertical gif images under the same conditions. For example, a picture of 500: 10 is smaller than a picture of 10: 500.

Interval progressive display

Gif supports optional interval progressive display

From the above characteristics, we can see that only 256colors of gif pictures are not suitable for photos, it is suitable for graphics that do not require high colors.

Features of Jpeg format:

Transparency

It does not support transparency.

Animation

It also does not support animation.

Attrition

Except for some, such as rotation (only 90,180,270 degrees), trimming, from the standard type to the advanced type, editing the original data of the image, all other operations on the jpeg image processing will cause its quality loss. So we usually use png as the transition format in the editing process.

Interlaced progressive display

It supports progressive interlaced display (this property is not supported by ie browsers, but ie is displayed when the entire image information is fully arrived).

It can be seen from the above that Jpeg is the most suitable web for photographic pictures and digital cameras.

Features of Png format:

Transparency

Png fully supports alpha transparency (transparent, translucent, opaque), although there are two strange phenomena in ie6 (discussed in more detail below)

Animation

It does not support animation

Lossless property

Png is a lossless image format, which means that you can do anything with png images without compromising image quality. This also makes png a transitional format for jpeg editing.

Horizontal scanning

Like GIF, png scans horizontally, which means that horizontal repeating colors are smaller than vertically repeating colors.

Interval progressive display

It supports progressive display at intervals, but causes the picture to become larger in size

The first kind of PNG is called PNG8 (Boolean transparency), which can be understood simply as static GIF

They all have only 256 colors and also support index transparency, that is, to specify whether a pixel is transparent or not.

The second PNG, also known as PNG8 (Alpha transparency), specifies the transparency of pixels, such as 50% transparency.

This advantage is smaller than PNG24/32, but the effect is the same.

The disadvantage is that IE6 does not support well and will display translucent pixels into full transparency.

The third kind of PNG is called PNG24

PNG24 is opaque, but there are many colors, more than 256colors

And the png24 exported in Photoshop is actually png32.

The fourth kind of PNG is called PNG32

Like photoshop's PSD, it is the default source file format for Fireworks and contains layer and channel information

The difference with PNG24 is that there is more transparent information.

The disadvantage is that IE6 does not support well and will show transparent areas with a blue-gray background: AlphaImageLoader and need to be specially tagged (VML) only through methods that affect performance.

Note:

Boolean transparent png8 can be displayed normally in any browser (just like gif).

Alpha transparent png8 works well in all browsers except ie6 and the following browsers.

Photoshop can only export Boolean transparent PNG8. Some png8 may have rough edges under IE6, because words, rounded corners, etc., usually have the effect of weakening edges. Can be trimmed before export)

Fireworks can export both Boolean transparent PNG8 and alpha transparent PNG8.

Other image formats are compared with PNG:

It is well known that GIF is suitable for graphics, JPEG is suitable for photos, and the PNG series is suitable for both.

Compared to GIF

For the same color value, pictures in gif format are smaller than those in png32 format. But png8 is the best choice.

Except that PNG8 does not support animation, PNG8 has all the features of GIF, but what is more advantageous over GIF is that it supports alpha transparency and better compression. So, in most cases, you should use PNG8 instead of GIF (except for very small images GIF will have better compression).

Compared to JPEG

JPEG has better compression than panchromatic PNG, so it also makes JPEG suitable for photos, but it is easy to cause quality loss in the process of editing JPEG, so panchromatic PNG is suitable as a transitional format for editing JPEG.

The above is all the contents of the article "what are the picture formats on the web web page"? thank you for reading! Hope to share the content to help you, more related knowledge, welcome to follow the industry information channel!

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