Application of filters is seldom necessary for editing cross-sectional images. Most commonly, filters are used for images scanned from textbooks or for damaged films or slides. Commonly employed filters include Dust and Scratches, Despeckle, Blur, Gaussian Blur, Sharpen, Unsharp Mask, and Sharpen Edges. When needed retouching price can found by selecting the Filter menu and choosing the desired filter. Some practice and trial and error are necessary, and the History palette is useful here.