In all television standards, the television picture is interlaced to reduce flicker. In the full-frame process, two fields are created: one consisting of only the odd lines and a second consisting of only the even lines, called fields. These fields are called fields
. Two of these fields add up to a full picture, a television picture with all lines, the even and the odd. In the PAL television standard, the fields work with a frame rate of 50 Hz, the full picture thus has 25 Hz.