int shomwarp(float *X, int W, int H, double M[9], float *x,
int w, int h, int o)
{
// if low order-interpolation, evaluate right away
if (o == 0 || o == 1 || o == 2 || o == -3)
return homwarp(X, W, H, M, x, w, h, o);
// otherwise, pre-filtering is required
bool r = prepare_spline(x, w, h, 1, o);
if (!r) return 2;
// warp the points
for (int j = 0; j < H; j++)
for (int i = 0; i < W; i++)
{
double p[2] = {i, j};
apply_homography(p, M, p);
p[0] += 0.5; // solve a mis-alignement convention
p[1] += 0.5;
float *out = X + (j*W + i);
evaluate_spline_at(out, x, w, h, 1, o, p[0], p[1]);
}
return 0;
}
int main(int c, char *v[])
{
if (c < 4 || c > 6)
return fprintf(stderr, "usage:\n\t"
"%s [-i {0|1|2|3}] hom w h [in [out]]\n", *v);
// 0 1 2 3 4 5
double H[9];
read_n_doubles_from_string(H, v[1], 9);
int ow = atoi(v[2]);
int oh = atoi(v[3]);
char *filename_in = c > 4 ? v[4] : "-";
char *filename_out = c > 5 ? v[5] : "-";
int w, h, pd;
float *x = iio_read_image_float_split(filename_in, &w, &h, &pd);
float *y = xmalloc(ow * oh * pd * sizeof*y);
for (int i = 0; i < pd; i++)
homwarp(y + i*ow*oh, ow, oh, H, x + i*w*h, w, h);
iio_save_image_float_split(filename_out, y, ow, oh, pd);
return 0;
}
