According to reviewer’s comment, we added Discussion Section. Discussion The previously proposed fast methods were mainly addressed to reduce complexity in the video encoder with the BD-rate loss. In [29], a fast intra mode decision algorithm was proposed and the result showed the encoding time savings of 51%~53% with BD-rate loss of 0.93%~1.08%. A low-complexity CTU (Coding Tree Unit) partition structure decision and fast intra mode decision were proposed in [30] and showed the average encoding time saving of 63% with the BD-rate loss of 1.93%. The fast encoders for video coding reduce only the encoder complexity but the BD-rates were always increased without decreasing the decoder complexity. However, the proposed fast inverse transform is different from the fast encoders in that it reduces the complexity in both the encoder and decoder while maintaining the BD- rate of the VVC standard. In the RA configuration, the proposed method reduces the average encoding and decoding times by approximately (4, 10) %, respectively, while maintaining average BD-rates. If the proposed inverse transform using the number of non-zero coefficients is applied to the VVC standard, the inverse transform of the VVC standard should be changed to include the proposed method. This fact can be demerit. However, the proposed method can be considered in the next-generation video coding standards because it achieves decoding run-time saving, while maintaining average BD-rate. In addition to that, the proposed method is more effective in high QP value than in low QP value, because the higher the QP value is, the fewer no-zero coefficients there are.
The authors should add a section where they discuss comparing their results with those of existing research. Also, they should clarify the limitations of the proposed method. Discussion Section: The authors did not respond accurately to this comment.