Effects of camera aperture correction on keying of broadcast video

This contribution discusses the effects of camera aperture correction in broadcast video on colour-based keying. The aperture correction is used to 'sharpen' an image and is one element that distinguishes the 'TV-look' from 'film-look'. If this sharpening is done excessively, as is the case in many TV productions then this significantly shifts the colours around object boundaries with high contrast. This paper discusses these effects and their impact on keying and describes a simple low-pass filter to compensate for them. Tests with two segmentation algorithms show that the proposed compensation is effectively decreasing the keying artefacts on object boundaries.