| 摘要 |
<p>The invention relates to a method of concealing errors in an image signal 101 transmitted in a macroblock compressed form. The method comprises a decoding step 102, a step 103 of detecting an erroneous macroblock, a classifying step and a correcting step 109 of correcting the erroneous macroblock in accordance with its class. The invention provides a cost effective classifying step. To this end, the classifying step consists of computing a gradient, in step 104, for each valid surrounding macroblock, for each pixel of a line or a column adjacent to the erroneous macroblock, evaluating the number of direction changes Cdir of the gradient in step 107, comparing the gradients with a first and a second threshold in steps 105 and 106, and classifying the erroneous macroblock in step 108 in accordance with the results of steps 104 to 107. The present invention is particularly relevant for correcting MPEG-compressed video signals, especially in systems where resource problems occur, for example, in mobile phones.</p> |
