A normal TV image consists of 480 lines. For standard broadcasts and videotapes, the television's electron beam scans this sequence of lines 30 times a second, but hitting only every other line: the odd-numbered lines when it scans from top to bottom, the even-numbered lines from bottom to top. This is called "interlace scanning." In "progressive scanning," the beam hits all the lines in each and every pass. This results in a more cohesive image, especially in scenes involving motion. However, progressive-scan images can be decoded only by digital TV sets. (Which is why DVD players with progressive-scan options also have outputs and circuitry for interlaced scanning.) Progressive-scan DVD players also have "component-video" outputs, which split the video signal into three parts—brightness, and two color-difference signals. (The outputs are marked Y, Pb, and Pr.) Some non-digital televisions have component inputs. If yours does, it's worth buying a progressive-scan DVD player, even though you can't use the progressive-scan feature, just to get the more accurate color.