Most filters are a perfect complement to post-processing. However, the digital world has often made us forget that filters can also be creatively used tools without a computer. Impressionistic effects like those created with the painter's tubes of paint, brushes, and varnish. Custom-made rainbows. Black masks and counter-masks for double and multiple exposures (e.g., doppelgänger photos). Romantic symbols, hearts, and cheeky keyholes as picture frames. Psychedelic color effects with colored filter films.