technoguy

As a unit of measurement for resolution, "television lines" or TVL refers to the maximum number of alternating black dots and intervening white spaces that can occur and be distinguished in a straight line whose length is equal to the diameter of the largest circle that fits in the screen or other area of reference. Photographers, when they refer to lines of resolution on film, count only the black lines or dots in a row in a test pattern, ignoring the intervening white spaces. The term TV Lines was introduced as an advertising gimmick to make TV, which has significantly less resolution than photographic film, seem to have more resolution than it does.