Fig. 1. SRCNN algorithm framework
Fig. 2. Proposed algorithm framework
Fig. 3. Function schematic. (a) ReLU; (b) e-ReLU
Fig. 4. Graph of train loss in the proposed method with the increase of iterations in the training process
Fig. 5. Comparison of the reconstruction of the baby_GT in Set 5. (a) Original image; (b) BI/33.91 dB; (c) ScSR/34.29 dB; (d) SRCNN/34.83 dB; (e) SRCNN-Ex/34.91dB; (f) proposed method/35.04 dB
Fig. 6. Comparison of the reconstruction of the butterfly_GT in Set 5. (a) Original image; (b) BI/24.04 dB; (c) ScSR/25.58 dB; (d) SRCNN/25.00 dB; (e) SRCNN-Ex/25.58 dB; (f) proposed method/27.91 dB
Fig. 7. Comparison of the reconstruction of the lenna in Set 14. (a) Original image; (b) BI/31.68 dB; (c) ScSR/32.64 dB; (d) SRCNN/32.53 dB; (e) SRCNN-Ex/32.78 dB; (f) proposed method/33.57 dB
Fig. 8. Comparison of the reconstruction of the pepper in Set 14. (a) Original image; (b) BI/32.38 dB; (c) ScSR/33.32 dB; (d) SRCNN/32.08 dB; (e) SRCNN-Ex/33.30 dB; (f) proposed method/34.57 dB
Fig. 9. Change graph of the average PSNR value for proposed algorithm in the Set 5 test set, with the number of iterations
Name | Size | Number | Stride | Padding |
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Conv1 | 5×5 | 64 | 1 | 0 | Conv2 | 3×3 | 32 | 1 | 0 | Deconv | 9×9 | 1 | 3 | 4 |
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Table 1. Parameter settings for each layer
Image | BI | ScSR | SRCNN | SRCNN-Ex | Proposed method |
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PSNR /dB | SSIM | PSNR /dB | SSIM | PSNR /dB | SSIM | PSNR /dB | SSIM | PSNR /dB | SSIM |
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Baby | 33.91 | 0.90 | 34.29 | 0.92 | 34.83 | 0.92 | 34.91 | 0.92 | 35.04 | 0.92 | Bird | 32.57 | 0.93 | 34.11 | 0.92 | 33.77 | 0.94 | 34.03 | 0.94 | 35.46 | 0.95 | Butterfly | 24.04 | 0.82 | 25.58 | 0.82 | 25.00 | 0.83 | 25.58 | 0.84 | 27.91 | 0.91 | Head | 32.88 | 0.80 | 33.17 | 0.80 | 33.42 | 0.82 | 33.42 | 0.82 | 33.67 | 0.83 | Women | 28.56 | 0.89 | 29.94 | 0.91 | 29.60 | 0.91 | 29.91 | 0.91 | 31.22 | 0.93 | Average | 30.39 | 0.87 | 31.42 | 0.87 | 31.32 | 0.88 | 31.57 | 0.89 | 32.66 | 0.91 |
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Table 2. PSNR and SSIM values on Set 5 test set
Image | BI | ScSR | SRCNN | SRCNN-Ex | Proposed method |
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PSNR /dB | SSIM | PSNR /dB | SSIM | PSNR /dB | SSIM | PSNR /dB | SSIM | PSNR /dB | SSIM |
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Baboon | 23.21 | 0.54 | 23.50 | 0.59 | 23.52 | 0.60 | 23.54 | 0.60 | 23.62 | 0.61 | Barbara | 26.25 | 0.75 | 26.39 | 0.75 | 26.76 | 0.78 | 26.84 | 0.78 | 26.57 | 0.78 | Bridge | 24.40 | 0.65 | 24.80 | 0.70 | 24.89 | 0.70 | 24.95 | 0.70 | 25.14 | 0.71 | Coastguard | 26.55 | 0.61 | 27.00 | 0.65 | 27.00 | 0.66 | 27.08 | 0.66 | 27.12 | 0.66 | Comic | 23.12 | 0.70 | 23.90 | 0.76 | 23.77 | 0.75 | 23.87 | 0.75 | 24.53 | 0.79 | Face | 32.82 | 0.80 | 33.10 | 0.81 | 33.38 | 0.82 | 33.40 | 0.82 | 33.71 | 0.83 | Flowers | 27.23 | 0.80 | 28.25 | 0.83 | 28.06 | 0.83 | 28.27 | 0.83 | 29.22 | 0.85 | Foreman | 31.16 | 0.91 | 32.04 | 0.91 | 32.09 | 0.91 | 32.01 | 0.91 | 33.65 | 0.94 | Lenna | 31.68 | 0.86 | 32.64 | 0.87 | 32.53 | 0.87 | 32.78 | 0.88 | 33.57 | 0.88 | Man | 27.01 | 0.75 | 27.76 | 0.78 | 27.56 | 0.78 | 27.72 | 0.78 | 28.33 | 0.80 | Monarch | 29.43 | 0.92 | 30.71 | 0.93 | 30.40 | 0.93 | 30.87 | 0.93 | 32.78 | 0.95 | Pepper | 32.38 | 0.87 | 33.32 | 0.87 | 32.08 | 0.88 | 33.30 | 0.88 | 34.57 | 0.89 | Ppt3 | 23.71 | 0.87 | 24.98 | 0.87 | 24.34 | 0.88 | 25.02 | 0.89 | 26.24 | 0.92 | Zebra | 26.63 | 0.80 | 27.95 | 0.82 | 27.74 | 0.84 | 28.37 | 0.84 | 29.11 | 0.85 |
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Table 3. PSNR and SSIM values on Set 14 test set
Method | 1000 times iteration | 105 times iteration | 2×105 times iteration | 8×108 times iteration |
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SRCNN | 477 | | | 381600000 | SRCNN-Ex | 1392 | | | 1113600000 | Proposed method | 141 | 14100 | 28200 | |
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Table 4. Comparison of training times