How to set css opacity: first create an HTML sample file; then use the img tag to introduce the image; finally add the css style to the style tag as "opacity: 0.5;" to set the transparency of the image.
The operating environment of this article: Windows7 system, HTML5&&CSS3 version, DELL G3 computer
css can use two methods: filter:alpha() and opacity Set the opacity. When you directly use opacity to set the opacity, the size range is 0-1. When you use filter:alpha(), the size range is between 1-100.
filter:alpha() and opacity both set transparency, but opacity is incompatible in IE8 and below; so the filter attribute must be set
a:hover { opacity: 1; filter: alpha(opacity=100);}When opacity is used to set transparency directly, the size range is between 0-1, and when it is 1, it is opaque. When filter:alpha() is used to set opacity, the size range is between 0-100, which is 100. It is opaque when
Basic attributes of filter:alpha()
filter：alpha（opacity，finishopacity，style，startX，startY，finishX，finishY）.
opacity: Transparency level, the range is 0-100, 0 represents completely transparent, 100 represents completely opaque.
finishopacity: When setting the transparency effect of the gradient, it is used to specify the transparency at the end, and the range is also 0 to 100.
style: Set the gradient transparent style. A value of 0 represents a uniform shape, 1 represents a linear shape, 2 represents a radial shape, and 3 represents a rectangle.
startX and startY: represent the starting X and Y coordinates of the gradient transparency effect.
finishX and finishY: represent the X and Y coordinates of the end of the gradient transparency effect.
opacity attribute:
opacity: value|inherit;
value specifies opacity. From 0.0 (fully transparent) to 1.0 (fully opaque).
inherit The value of the opacity attribute should be inherited from the parent element.
Example:
<!DOCTYPE html>
<html>
<head>
<style>
img {
opacity: 0.5;
}
</style>
</head>
<body>
<h1 id="图像透明度">图像透明度</h1>
<p>opacity 属性规定元素的透明度。值越低，越透明：</p>
<p>50% 不透明度的图像：</p>
<img src="/static/imghwm/default1.png" data-src="/i/photo/tulip-red.jpg" class="lazy" alt="Tulip" style="max-width:90%" style="max-width:90%">
</body>
</html>Effect:
Recommended study: "css video tutorial"
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