CSS Opacity Property
The opacity-level describes the transparency-level, it ranges from 0.0 to 1.0. The level 0.0 is completely transparent, 0.5 is 50% see-through and level 1.0 is not transparent. Opacity has a default initial value of 1 (100% opaque).
img {
opacity: 0.5;
}
Example of Image Opacity by using CSS .class
<!DOCTYPE html>
<html>
<head> // Head section start
<style> // internal CSS code
.img_op {
opacity: 0.3;
height: 200px;
width; 200px;
}
</style>
</head> // Head section ended
<body> // Body section start
<img src="URL_image" class="img_op" />
</body> // Body section ended
</html>