// evaluate the L2 distance between the image A and the image B translated by d
//
// A, B: input images
// w: width
// h: heigth
// d: translation vector
//
// return value: normalized L2 distance
//
float eval_displacement(float *A, float *B, int w, int h, int d[2])
{
long double r = 0;
int woff = w/16;
int hoff = h/16;
int npoints = (w-2*woff)*(h-2*hoff);
for (int j = hoff; j < h-hoff; j++)
for (int i = woff; i < w-woff; i++)
{
long double a = getpixel_0(A, w, h, i, j);
long double b = getpixel_0(B, w, h, i-d[0], j-d[1]);
r += (a - b) * (a - b);///(1.0*npoints);
}
r = sqrtl(r/npoints);
return r;
}
// zoom-out by a factor 2
//
// in: input image
// iw: input image width
// ih: input image height
// out: output image to be filled-in
// ow: output image width (supplied by the user)
// oh: output image height (supplied by the user)
//
static void zoom_out_by_factor_two(float *out, int ow, int oh,
float *in, int iw, int ih)
{
assert(abs(2*ow-iw) < 2);
assert(abs(2*oh-ih) < 2);
for (int j = 0; j < oh; j++)
for (int i = 0; i < ow; i++)
{
float a[4];
a[0] = getpixel_0(in, iw, ih, 2*i, 2*j);
a[1] = getpixel_0(in, iw, ih, 2*i+1, 2*j);
a[2] = getpixel_0(in, iw, ih, 2*i, 2*j+1);
a[3] = getpixel_0(in, iw, ih, 2*i+1, 2*j+1);
out[ow*j + i] = (a[0] + a[1] + a[2] + a[3])/4;
}
}
// apply a translation to the given image
//
// in: input image
// w: width
// h: height
// dx: horizontal displacement
// dy: vertical displacement
// out: output image, to be filled-in
void apply_translation(float *out, int dx, int dy, float *in, int w, int h)
{
for (int j = 0; j < h; j++)
for (int i = 0; i < w; i++)
{
int ii = i - dx;
int jj = j - dy;
out[j*w+i] = getpixel_0(in, w, h, ii, jj);
}
}
void cut_n_parts(float *im, int w, int h, int n, float **out)
{
int w1 = floor(w/n);
int h1 = floor(h/n);
for(int i = 0 ; i < n ; i++)
for(int j = 0 ; j < n ; j++)
for (int k = 0 ; k < w1 ; k++)
for (int l = 0 ; l < h1 ; l++)
{
out[j*n+i][l*w1+k] = getpixel_0(im, w, h, j*w1+k, i*h1+l);
}
}
