| 49 | // --- Helper: compute PSNR between two RGBA buffers --- |
| 50 | |
| 51 | static double computePSNR(const uint8_t* a, const uint8_t* b, int w, int h) |
| 52 | { |
| 53 | double mse = 0; |
| 54 | int n = w * h * 4; |
| 55 | for (int i = 0; i < n; ++i) |
| 56 | { |
| 57 | double d = static_cast<double>(a[i]) - static_cast<double>(b[i]); |
| 58 | mse += d * d; |
| 59 | } |
| 60 | mse /= n; |
| 61 | if (mse == 0.0) |
| 62 | return 100.0; |
| 63 | return 10.0 * std::log10(255.0 * 255.0 / mse); |
| 64 | } |
| 65 | |
| 66 | // --- Image construction --- |
| 67 |