This is a tonal rotation filter.
Assuming your original picture is yellow, this code will make your yellow picture purple.
The complete code is style="filter: hue-rotate(270deg);"
You can use star.png as a test.
I have given the picture here, you will understand if you try to do it.
Demo:
<p><img alt="" src="/upload/images/star.png" /></p>
<p><img alt="" src="/upload/images/star.png" style="filter: hue-rotate(270deg);" /></p>
Nice!
This means you don't need to use two pictures to express the color changes of the same object.
Saved bandwidth.