Abstract: An image signal processing apparatus is provided and includes a YC separator circuit for extracting a chrominance signal from an image signal, a signal level detector circuit for outputting a signal level detecting signal by detecting a signal level of the chrominance signal and a signal level corrector circuit for correcting a signal level of the signal level detecting signal to generate a key signal according to the chrominance signal, the signal level corrector circuit including an oversampler circuit.

Abstract: Image switching apparatus for selecting first or second video signals to be broadcasted, displayed or recorded, thereby producing special video effects. The output of a random noise generator is filtered by a filtering device having a variable filter characteristic that is controlled by an adjustable filter control signal. The filtered random noise signal is compared with a reference level that changes with respect to time, and the output of the comparator controls a switch to select one or the other of the video signals, depending upon whether the filtered random noise signal exceeds the changing reference level, thus producing special image switching effects.