Set the white against a neutral or bold hue for a touch of texture or larger burst of color. Apply stripes of masking tape down the doors, and paint them a creamy neutral color or vibrant, saturated one. Elegant, subtle stripes of bold, dramatic tones can result. Paint the surrounding walls to provide contrast to the closet doors, or paint the trim if the doors have any.
Decals allow you to place a pattern or image on your doors on a temporary basis, so you can remove or rearrange them when you want something fresh. Place a repeating motif of a tiny design on the white surface. Bold primary colors create a mod look, or use soft, subtle pastels or earth tones for a muted effect. You can also place oversized decals of images like trees on the doors to create large wall art. If you'd like to break up a larger decal, cut it into sections, and apply it over the area of more than one door for a broken up image with negative space.
Depending on the type of closet doors you have, wall hangings or prints can liven them up. If your doors swing open, a cluster of framed wall art securely mounted on it can turn the closet doors into decorative wall space when you're not using the closet. Experiment with clustering different sizes, or simply place a large framed piece on each door. For pocket or accordion doors, mount posters, prints or photographs without frames, or matte them instead. Mount them with paint-safe putty or another adhesive that won't ruin the surface paint.
If your white closet doors don't seem to go with the rest of the room's design, you can paint over them and create an accent wall. You can also cover them in wallpaper and add faux hardware like crystal knobs or door pulls. Painting trim or scroll work on the perimeter of the doors can also make them look like a large armoire. Removing the closet doors and installing colorful curtains can also make the room seem larger and add texture.