Abstract: The present invention relates to a digital data filtering circuit. This digital data filtering circuit is able to implement the calculation steps of a discrete transform of a set of 8 original data (w), and calculating an inverse discrete transform of the set of transformed data thus obtained. For this purpose, it comprises a first filtering module (FILo1) intended to filter the odd transformed data or the 3 odd transformed data items having the highest frequencies in the set of transformed data, and a second filtering module (FILo2) connected to the first filtering module and intended to filter the 2 odd transformed data having the highest frequencies in the set of transformed data.