Table 1 Parameters set for the original BM3D
| Â | Symbol | Description | Fast BM3D | Normal BM3D | |
|---|---|---|---|---|---|
|  |  |  |  | σ≤40 | σ≥40 |
Step 1 (hard) parameters | \(T_{\text {hard}}^{\mathrm {2D}}\) | 2D transform | Bior1.5 | Bior1.5 | DCT |
| Â | \(T_{\text {hard}}^{\mathrm {3D}}\) | 3D transform | Haar | Haar | Haar |
| Â | \(N_{1}^{\text {hard}}\) | Patch size | 8 | 8 | 12 |
| Â | \(N_{2}^{\text {hard}}\) | 3D array size | 16 | 16 | 16 |
| Â | \(N_{\mathrm {step1}}^{\text {hard}}\) | Patch step | 6 | 3 | 4 |
| Â | \(N_{\text {search}}^{\text {hard}}\) | Window size | 25 | 39 | 39 |
| Â | \(N_{\mathrm {step2}}^{\text {hard}}\) | Window step | 6 | 1 | 1 |
|  | \(N_{\mathrm {Prev.}}^{\text {hard}}\) | Small window | 3 | – | – |
|  | β hard | Kaiser window | 2.0 | 2.0 | 2.0 |
|  | λ 2D | 2D thresholding | 0 | 0 | 2.0 |
|  | λ 3D | 3D thresholding | 2.7 | 2.7 | 2.8 |
| Â | \(T_{\text {match}}^{\text {hard}}\) | Distance | 2500 | 2500 | 5000 |
Step 2 (Wiener) parameters | \(T_{\text {Wiener}}^{\mathrm {2D}}\) | 2D transform | DCT | DCT | DCT |
| Â | \(T_{\text {Wiener}}^{\mathrm {3D}}\) | 3D transform | Haar | Haar | Haar |
| Â | \(N_{1}^{\text {Wiener}}\) | Patch size | 8 | 8 | 11 |
| Â | \(N_{2}^{\text {Wiener}}\) | 3D array size | 16 | 32 | 32 |
| Â | \(N_{\mathrm {step1}}^{\text {Wiener}}\) | Patch step | 5 | 3 | 6 |
| Â | \(N_{\text {search}}^{\text {Wiener}}\) | Window size | 25 | 39 | 39 |
| Â | \(N_{\mathrm {step2}}^{\text {Wiener}}\) | Window step | 5 | 1 | 1 |
|  | \(N_{\mathrm {Prev.}}^{\text {Wiener}}\) | Small window | 2 | – | – |
|  | β Wiener | Kaiser window | 2.0 | 2.0 | 2.0 |
| Â | \(T_{\text {match}}^{\text {Wiener}}\) | Distance | 400 | 400 | 3500 |