In this contribution, an alternative simple gradient calculation is proposed for the samples on CU boundaries without interpolation of the prediction samples in the extended area. After CU boundary samples are directly copied into the extended area, the gradients for the samples on the CU boundaries are calculated with the same gradient filter as that for the samples inside CU. It is reported that the average luma BD-rate is reportedly 0.11% with encoding times of 99% and decoding times of 98% for RA configuration compared to VTM-3.0. Compared to CE9.1.1.c, it is reported that average luma BD-rate is reportedly 0.01% with encoding times of 100% and decoding times of 100% for RA configuration.