| 386 | const DecimateAlpha* ytab, int ytab_size, const int* yofs); |
| 387 | |
| 388 | static inline void interpolate_lanczos4(float x, float* coeffs) { |
| 389 | static const double s45 = 0.70710678118654752440084436210485; |
| 390 | static const double cs[][2] = {{1, 0}, {-s45, -s45}, {0, 1}, {s45, -s45}, |
| 391 | {-1, 0}, {s45, s45}, {0, -1}, {-s45, s45}}; |
| 392 | |
| 393 | if (x < FLT_EPSILON) { |
| 394 | for (int i = 0; i < 8; i++) |
| 395 | coeffs[i] = 0; |
| 396 | coeffs[3] = 1; |
| 397 | return; |
| 398 | } |
| 399 | |
| 400 | float sum = 0; |
| 401 | double y0 = -(x + 3) * MEGCV_PI * 0.25, s0 = sin(y0), c0 = cos(y0); |
| 402 | for (int i = 0; i < 8; i++) { |
| 403 | double y = -(x + 3 - i) * MEGCV_PI * 0.25; |
| 404 | coeffs[i] = (float)((cs[i][0] * s0 + cs[i][1] * c0) / (y * y)); |
| 405 | sum += coeffs[i]; |
| 406 | } |
| 407 | |
| 408 | sum = 1.f / sum; |
| 409 | for (int i = 0; i < 8; i++) |
| 410 | coeffs[i] *= sum; |
| 411 | } |
| 412 | |
| 413 | template <typename T, typename WT, typename AT> |
| 414 | struct HResizeLanczos4 { |
no test coverage detected