| 摘要 |
The invention relates to a de-emphasis filter for a SECAM decoder to convert an input image data sequence into filtered image data, comprising at least one recursion register (1) to store an auxiliary value obtained on the basis of an inputted image data value. The invention further comprises an arithmetic circuit (3, 5, 7, 9, 11) which generates a new auxiliary value to replace the content of the recursion register on the basis of both the auxiliary value and the new inputted image data value and also generates a filtered image data value. In order to carry out the task of determining achromatic values in addition to that of performing de-emphasis filtering, the filter is also provided with a device (15, 17) to store and output a value which represents the estimated value of the achromatic value of the SECAM signal. Said filter also has a first switch (13) to include and register the outputted estimated value in the recursion register (1) at the beginning of each burst gate period of the SECAM signal. The arithmetic circuit (3, 5, 7, 9, 11) outputs an estimated value that is updated on the basis of said burst signal value and that is calculated on the basis of the registered estimated value and at least one value of the burst signal. |
