Abstract: Noise reduction is an important feature in consumer television. This is realized by spatial, temporal or spatio-temporal filters. Spatial filters require pixels from within one image, while temporal filters require samples from two or more successive images. The spatio-temporal filter unit (100) integrates spatial and implicit motion-compensated temporal noise reduction in one filter. For the motion compensation, no motion vectors are required. The spatio-temporal filter unit (100) is provided with a sigma filter (112) having one filter kernel (107) designed to operate on the pixels from both a current image and from the output of the spatio-temporal filter unit, being a temporally recursive filtered image. The operation of the spatio-temporal filter unit (100) can be adjusted by varying the thresholds of the sigma filter (112) and the selection of pixels. The adjustments can be controlled by a motion estimator (222), a motion detector (224) and a noise estimator (220).

Abstract: Noise reduction is an important feature in consumer television. This is realized by spatial, temporal or spatio-temporal filters. Spatial filters require pixels from within one image, while temporal filters require samples from two or more successive images. The spatio-temporal filter unit (100) according to this invention integrates spatial and implicit motion-compensated temporal noise reduction in one filter. For the motion compensation no motion vectors are required. The spatio-temporal filter unit (100) is provided with a sigma filter (112) comprising one filter kernel (107) designed to operate on the pixels from both a current image and from the output of the spatio-temporal filter unit, being a temporally recursive filtered image. The operation of the spatio-temporal filter unit (100) can be adjusted by varying the thresholds of the sigma filter (112) and the selection of pixels. The adjustments can be controlled by a motion estimator (222), a motion detector (224) and a noise estimator (220).

Abstract: Character generator which provides the displayed characters, when displayed simultaneously with a video picture, with a shadow in a complimentary or programmable color so that the readability is optimum under all circumstances without any unnecessary blanking of the video picture. To this end the character generator (43) is adapted to alternately address both the pixel to be displayed and at least one adjacent pixel in a character memory (171). A blanking signal (FBL), which blanks the received video picture dependent on both the pixel to be displayed and the adjacent pixel, is generated in a blanking circuit (20). While the video picture is being blanked, the characters are displayed in a foreground color and the shadow is displayed in a background color. The invention is applicable in television receivers, camera recorders and the like, using a character generator for displaying locally generated operating information (On Screen Display) or information supplied by an external source (Teletext).