Apparatus for combining an auxiliary image and a main image includes a source of a main image video signal and a source of samples representing an auxiliary image video signal having successive fields. A quincunx subsampler is coupled to the auxiliary image sample source and subsamples the auxiliary image samples in either a first sample pattern in which samples are taken at a first set of horizontal locations, or a second sample pattern in which samples are taken at a second set of horizontal locations substantially midway between the first set, all in response to a control signal. A signal combiner is coupled to the quincunx subsampler and the main image signal source, and combines the main image signal and a signal representing the quincunx subsampled auxiliary image samples to generate a signal representing a combine image of the main and auxiliary images. A control circuit generates the quincunx subsampler control signal so that the quincunx subsampler takes samples in one of the sample patterns at the beginning of each auxiliary image video signal field, and in the other sample pattern after a switch time calculated so that the quincunx subsampled auxiliary image samples in the combined image all are taken by the same sample pattern.