The R-value of Contrast-phys+ on UBFC-RPPG is low

[Harry2345]

Hello! Recently, I have been replicating Contrast-phys+ and following the steps to train and test it on UBFC-RPPG. The heart rate values are very close, but the calculated R-value always seems to be low. Do you know why? Here is the method I used to calculate the metrics:

subject:/home/zhixin_yan/project/contrast-phys/contrast-phys+/results/default/23/1/44.npy hr_rppg:89.0 hr_bvp:89.0 MAE:0.7537042662656902 MSE:0.8300663503050997 RMSE:0.9110797716474116 R:0.5596756484461523

subject:/home/zhixin_yan/project/contrast-phys/contrast-phys+/results/default/23/1/49.npy hr_rppg:87.0 hr_bvp:86.0 MAE:0.7199145203866735 MSE:0.7962145399996426 RMSE:0.8923085452911692 R:0.5253803322031185

subject:/home/zhixin_yan/project/contrast-phys/contrast-phys+/results/default/23/1/45.npy hr_rppg:112.0 hr_bvp:112.0 MAE:0.7285037279791446 MSE:0.7469296112617089 RMSE:0.8642508960144091 R:0.7825049275582626

subject:/home/zhixin_yan/project/contrast-phys/contrast-phys+/results/default/23/1/46.npy hr_rppg:94.00000000000001 hr_bvp:93.0 MAE:0.7080922650721068 MSE:0.7148581794156879 RMSE:0.8454928618360346 R:0.44332718968619483

subject:/home/zhixin_yan/project/contrast-phys/contrast-phys+/results/default/23/1/39.npy hr_rppg:86.0 hr_bvp:86.0 MAE:0.6574607328649096 MSE:0.707239877504444 RMSE:0.8409755510741344 R:0.5742140765121817

subject:/home/zhixin_yan/project/contrast-phys/contrast-phys+/results/default/23/1/43.npy hr_rppg:99.99999999999999 hr_bvp:99.99999999999999 MAE:0.7248150684600015 MSE:0.7970786218834163 RMSE:0.892792597350256 R:0.6297846759769277

subject:/home/zhixin_yan/project/contrast-phys/contrast-phys+/results/default/23/1/38.npy hr_rppg:112.0 hr_bvp:112.0 MAE:0.7259880192697764 MSE:0.7252420109154502 RMSE:0.8516114201415163 R:0.8895395112121949

subject:/home/zhixin_yan/project/contrast-phys/contrast-phys+/results/default/23/1/42.npy hr_rppg:98.0 hr_bvp:98.0 MAE:0.715046724078873 MSE:0.7930097950294874 RMSE:0.8905109741207502 R:0.7976646616673656

subject:/home/zhixin_yan/project/contrast-phys/contrast-phys+/results/default/23/1/40.npy hr_rppg:88.0 hr_bvp:88.0 MAE:0.6873482923836377 MSE:0.7130528581768157 RMSE:0.8444245722246693 R:0.5340293702773984

subject:/home/zhixin_yan/project/contrast-phys/contrast-phys+/results/default/23/1/41.npy hr_rppg:99.99999999999999 hr_bvp:99.99999999999999 MAE:0.6872299273870676 MSE:0.676695129281339 RMSE:0.822614812218537 R:0.59450306089585

subject:/home/zhixin_yan/project/contrast-phys/contrast-phys+/results/default/23/1/47.npy hr_rppg:117.00000000000001 hr_bvp:117.00000000000001 MAE:0.6963591330861216 MSE:0.6587551545136888 RMSE:0.8116373294234863 R:0.6429711341256403

subject:/home/zhixin_yan/project/contrast-phys/contrast-phys+/results/default/23/1/48.npy hr_rppg:92.0 hr_bvp:92.0 MAE:0.803484226944761 MSE:0.8820074963485776 RMSE:0.9391525415759558 R:0.3685707944758343 MAE:0.7173289086815637 MSE:0.7534291353862799 RMSE:0.8680029581667794 R:0.5585138808441661