##Browser Compatibility
CSS filters are not currently supported in all browsers:
http://caniuse.com/#search=filters
For cross-browser compatibility, the image needs to be modified and uploaded in final form. CSS filters do, however, allow for quick testing of different filtering combos before editing an image with photo-editing software.
##Resources
CSS-Tricks article on CSS filters (including examples):
https://css-tricks.com/almanac/properties/f/filter/
w3schools article on CSS filters:
http://www.w3schools.com/cssref/css3_pr_filter.asp
UI for generating CSS filters:
http://html5-demos.appspot.com/static/css/filters/index.html