What is the best way to make black and white images for posts in WP?

Question

WordPress

I have a layout task, to display posts on Wordpress with black and white thumbnails (pictures), but when you hover over a post, the post picture should become color, that is, there should be both color and black and white photos in the gallery, how best to implement this ? given that it is better not to load the site with plugins and so on? thank you in advance

Answer 1

https://developer.mozilla.org/en/docs/Web/CSS/filter
Apply a black and white filter to CSS. All.