A software routine that changes the appearance of an image or part of an image by altering the shades and colors of the pixels in some manner. Filters are used to increase brightness and contrast as well as to add a wide variety of textures, tones and special effects to a picture. See graphics filter and Photoshop plug-in.
The original painting was photographed and scanned into the computer. The following images were created in Photoshop by applying a filter to the original. (From "Moonlit Gladiolas" by Barbara Postel. Image courtesy of Pyramid Studios, www.artistexpo.com)
Gaussian Blur Filter
Find Edges Filter
Glowing Edges Filter
Image editing can also make subtle changes. Look at the eyes in the original photo (top) compared to the bottom, which was changed in Corel's PhotoPaint using the Mesh Warp filter. (Image courtesy of Corel Corporation.)
Enhance, Send and Post
With a couple of taps on the Instagram app in the iPhone, the original photo (top) was greatly enhanced. Instagram includes a variety of image filters that users can choose before sending and posting their photos to Facebook, Twitter, foursquare or Tumblr.