Method and apparatus for coding/decoding picture data

The disclosure relates to a method for encoding image data, the method including intra-predicting, or predicting by combining inter-prediction and intra-prediction, a first block of the image data by using an intra-prediction mode using a first single transformation obtained by taking account of the first block size. The disclosure also relates to a method for encoding image data, a variable coding length being used for signaling a plurality of Prediction Modes by the encoding, the method comprising:-intra-predicting a first block of the image data by using an intra-prediction mode using a first transformation, the first transformation being obtained by taking account of the first block size, -encoding information signaling a use of the intra-prediction mode in a bitstream, the information being encoded as one of the plurality of Prediction Modes. The disclosure further relates to the corresponding decoding methods, devices and media.