The range between lights and darks in an image. Proper contrast is important so that an image appears realistic. That act of adjusting contrast for proper visual results. Curve As in tone curve, or color correction curve. The lower left end of the curve typically represents the dark portions of a picture and an upward bend will typically lighten the shadows.
Similar capabilities exist by working with the middle or highlight parts of the curve.
In this way it is possible to alter only certain tone ranges of an image without making un-wanted changes in other parts of the image. DPI An improper expression of the resolution of a scanned image. Drum Scanner A type of scanner on which original artwork is attached to the outside of a spinning glass drum. This type of scanner gives the best quality result. An expression of the density difference between highlights and shadows.