One of several strategies used in deinterlacing video. Bobbing is where each field is displayed all by itself in sequence. The intermediate lines are created by interpolating from the lines above and below it. This has the effect of reducing the vertical resolution at any instant of time by half (but it doesn't seem as bad as this, thanks to the interpolation), but smoothing pans because the two fields are displayed one fiftieth of a second apart. This is useful for video sourced material, in which the two interlaced fields constituting the full video frame were actually captured at slightly different times from each other, causing a combed effect on vertical lines. Compare weave.