Make Images Black & White

CSS

-webkit-filter: grayscale(1);
-moz-filter: grayscale(1);
-o-filter: grayscale(1);
-ms-filter: grayscale(1);
filter: grayscale(1);
filter: url("data:image/svg+xml;utf8,<svg xmlns=\'http://www.w3.org/2000/svg\'><filter id=\'grayscale\'><feColorMatrix type=\'matrix\' values=\'0.3333 0.3333 0.3333 0 0 0.3333 0.3333 0.3333 0 0 0.3333 0.3333 0.3333 0 0 0 0 0 1 0\'/></filter></svg>#grayscale");
filter: gray;

LESS

@filterString: ~"grayscale(1)";
-webkit-filter: @filterString;
-moz-filter: @filterString;
-o-filter: @filterString;
-ms-filter: @filterString;
filter: @filterString;
filter: url("data:image/svg+xml;utf8,<svg xmlns=\'http://www.w3.org/2000/svg\'><filter id=\'grayscale\'><feColorMatrix type=\'matrix\' values=\'0.3333 0.3333 0.3333 0 0 0.3333 0.3333 0.3333 0 0 0.3333 0.3333 0.3333 0 0 0 0 0 1 0\'/></filter></svg>#grayscale");
filter: gray;

To remove the grayscale effect:

-webkit-filter: grayscale(0);
-moz-filter: grayscale(0);
-o-filter: grayscale(0);
-ms-filter: grayscale(0);
filter: grayscale(0);
filter: url("data:image/svg+xml;utf8,<svg xmlns=\'http://www.w3.org/2000/svg\'><filter id=\'grayscale\'><feColorMatrix type=\'matrix\' values=\'1 0 0 0 0, 0 1 0 0 0, 0 0 1 0 0, 0 0 0 1 0\'/></filter></svg>#grayscale");

black / white / greyscale / filters / less / css