void Image::Shift(double sx, double sy)
{
for(int y = 0; y < height; y++) {
int y_ = (0 < sy) ? height - 1 - y : y;
for(int x = 0; x < width; x++) {
int x_ = (0 < sx) ? width - 1 - x : x;
if(sx == floor(sx) && sy == floor(sy))
GetPixel(x_, y_) = (ValidCoord(x_ - (int) sx, y_ - (int) sy))
? GetPixel(x_ - (int) sx, y_ - (int) sy) : Pixel(0, 0, 0);
else {
if(sampling_method == IMAGE_SAMPLING_HAT) {
if(ValidCoord(x_ - (int) sx, y_ - (int) sy)) {
float h_r, h_g, h_b, h_all, h_tmp;
h_r = h_g = h_b = h_all = 0.0f;
for(int c = -1; c < 2; c++) {
for(int r = -1; r < 2; r++) {
if(ValidCoord(x_ - (int) sx + r, y_ - (int) sy + c)) {
h_tmp = hat(-((int) sx) + r + (float) sx)
* hat(-((int) sy) + c + (float) sy);
h_all += h_tmp;
h_r += (float) GetPixel(x_ - (int) sx + r, y_ - (int) sy + c).r * h_tmp;
h_g += (float) GetPixel(x_ - (int) sx + r, y_ - (int) sy + c).g * h_tmp;
h_b += (float) GetPixel(x_ - (int) sx + r, y_ - (int) sy + c).b * h_tmp;
}
}
}
GetPixel(x_, y_).SetClamp(h_r / h_all, h_g / h_all, h_b / h_all);
}
else GetPixel(x_, y_) = Pixel(0, 0, 0);
}
else if (sampling_method == IMAGE_SAMPLING_MITCHELL) {
if (ValidCoord(x_ - (int) sx, y_ - (int) sy)) {
float h_r, h_g, h_b, h_all, h_tmp;
h_r = h_g = h_b = h_all = 0.0f;
for(int c = -4; c < 5; c++) {
for(int r = -4; r < 5; r++) {
if(ValidCoord(x_ - (int) sx + r, y_ - (int) sy + c)) {
h_tmp = mitchell(-((int) sx) + r + (float) sx)
* mitchell(-((int) sy) + c + (float) sy);
h_all += h_tmp;
h_r += (float) GetPixel(x_ - (int) sx + r, y_ - (int) sy + c).r * h_tmp;
h_g += (float) GetPixel(x_ - (int) sx + r, y_ - (int) sy + c).g * h_tmp;
h_b += (float) GetPixel(x_ - (int) sx + r, y_ - (int) sy + c).b * h_tmp;
}
}
}
GetPixel(x_, y_).SetClamp(h_r / h_all, h_g / h_all, h_b / h_all);
}
else GetPixel(x_, y_) = Pixel(0, 0, 0);
}
}
}
}
}
static float catmull_rom_filter(float t)
{
return mitchell(t, 0.0f, .5f);
}
static float mitchell_filter(float t)
{
return mitchell(t, 1.0f / 3.0f, 1.0f / 3.0f);
}
static Resample_Real catmull_rom_filter(Resample_Real t)
{
return mitchell(t, 0.0f, .5f);
}
static Resample_Real mitchell_filter(Resample_Real t)
{
return mitchell(t, 1.0f / 3.0f, 1.0f / 3.0f);
}
Pixel Image::Sample (double u, double v, double sx, double sy)
{
// To sample the image in scale and shift
// This is an auxiliary function that it is not essential you fill in or
// you may define it differently.
// u and v are the floating point coords of the points to be sampled.
// sx and sy correspond to the scale values.
// In the assignment, it says implement MinifyX MinifyY MagnifyX MagnifyY
// separately. That may be a better way to do it.
// This hook is primarily to get you thinking about that you have to have
// some equivalent of this function.
if (sampling_method == IMAGE_SAMPLING_POINT) {
// Your work here
return GetPixel((int) round(u / sx), (int) round(v / sy));
}
else if (sampling_method == IMAGE_SAMPLING_HAT) {
int sumr, sumg, sumb;
sumr = sumg = sumb = 0;
float xdif = 0;
float ydif = 0;
if (sx < 1)
xdif = 1 / sx;
else
xdif = 1;
if (sy < 1)
ydif = 1 / sy;
else
ydif = 1;
float n = 0;
for (int x = round(u / sx - xdif); x <= round(u / sx + xdif); x++) {
float hu = hat((x - u / sx) / xdif);
for (int y = round(v / sy - ydif); y <= round(v / sy + ydif); y++) {
float hv = hat((y - v / sy) / ydif);
float h = hu * hv;
n += h;
if (!ValidCoord(x, y))
continue;
Pixel curr = GetPixel(x, y);
sumr += h * curr.r;
sumg += h * curr.g;
sumb += h * curr.b;
}
}
sumr /= n;
sumg /= n;
sumb /= n;
if (sumr > 255)
sumr = 255;
else if (sumr < 0)
sumr = 0;
if (sumg > 255)
sumg = 255;
else if (sumg < 0)
sumg = 0;
if (sumb > 255)
sumb = 255;
else if (sumb < 0)
sumb = 0;
return Pixel(sumr, sumg, sumb);
}
else if (sampling_method == IMAGE_SAMPLING_MITCHELL) {
int sumr, sumg, sumb;
sumr = sumg = sumb = 0;
float xdif = 0;
float ydif = 0;
if (sx < 1)
xdif = 1 / sx;
else
xdif = 1;
if (sy < 1)
ydif = 1 / sy;
else
ydif = 1;
float n = 0;
for (int x = round(u / sx - xdif); x <= round(u / sx + xdif); x++) {
float hu = mitchell((x - u / sx) / xdif);
for (int y = round(v / sy - ydif); y <= round(v / sy + ydif); y++) {
float hv = mitchell((y - v / sy) / ydif);
float h = hu * hv;
n += h;
if (!ValidCoord(x, y))
continue;
Pixel curr = GetPixel(x, y);
sumr += h * curr.r;
sumg += h * curr.g;
sumb += h * curr.b;
}
}
sumr /= n;
sumg /= n;
sumb /= n;
if (sumr > 255)
sumr = 255;
else if (sumr < 0)
sumr = 0;
if (sumg > 255)
sumg = 255;
else if (sumg < 0)
sumg = 0;
if (sumb > 255)
sumb = 255;
else if (sumb < 0)
sumb = 0;
return Pixel(sumr, sumg, sumb);
}
else {
fprintf(stderr,"I don't understand what sampling method is used\n") ;
exit(1) ;
}
return Pixel() ;
}