When you add a image to your site, your code will look like this :
Now add style="opacity:0.4;filter:alpha(opacity=40)" to your code as below.
Now your code will look like this:
Note: You can change 40 as your choice.
<img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhHcMwwxSqoLdqS5b3IJoAINWDBt7dlrD4X9z64DN6pvfBqfQBf_gBUtfQBYsuaKbT1h76CylmbgJ_L4nms4j6sKBROxJm9CPK2I9jHdZwp5twl7_RQWfdt2I5Py0NuVCXHjITjCaEdxuU/" alt="leaves" height="300" width="400" />Result:
Now add style="opacity:0.4;filter:alpha(opacity=40)" to your code as below.
Now your code will look like this:
<img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhHcMwwxSqoLdqS5b3IJoAINWDBt7dlrD4X9z64DN6pvfBqfQBf_gBUtfQBYsuaKbT1h76CylmbgJ_L4nms4j6sKBROxJm9CPK2I9jHdZwp5twl7_RQWfdt2I5Py0NuVCXHjITjCaEdxuU/" alt="leaves" height="300" width="400" style="opacity:0.4;filter:alpha(opacity=40)" />See the result:Note: You can change 40 as your choice.