Abstract: A process for adaptive quantization with quantization errors which have little disturbing visual effects, using a digital block-related process for data reduction in digital images or image sequences. It is provided in this process that an image to be transmitted is subdivided into a multiplicity of blocks, and that there is calculated for each block a parameter for setting the quantization assigned to this block. The calculation of this parameter is performed in this case with the aid of a subdivision of each block into subregions, there being calculated for each subregion an activity measure with the aid of which a quantization parameter is determined for each subregion. Finally, the quantization parameters of all subregions are summed up within the blocks in the case of all blocks and multiplicatively scaled.

Abstract: A method for reducing what are referred to as blocking artifacts in a video scene coding with discrete cosine transformation (DCT) at a low data rate is provided in a video signal transmission system, having a transmit-side video signal input to which a video signal to be transmitted is supplied. A transmit-side coder transmits frequency limitation parameters allocated to the individual blocks of the video signal to be divided into a plurality of blocks at a receive-side decoder, via a transmission channel, together with a block-associated video sub-signal that is coded by the coder. The frequency limitation parameters are used at the receive side to control a block filter function at the output of the decoder that outputs a decoded video signal, controlling this for postprocessing of the decoded video signal for the purpose of reducing the blocking artifacts.

Abstract: An improved method and apparatus for producing a cross sectional image of a body using a method where the distribution of the attenuation coefficients of ionizing rays passing through the body in a cross sectional plane is derived using a convolution method, in which a plurality of convolution kernels are permanently stored for use as desired and measured data obtained and convoluted therewith after which values are added and displayed on a display device permitting different settings of image constrast to thereby harmonize the cross sectional image of the body.