mark/small-image-descriptors
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Move DCT calculation

Browse Source
This commit is contained in:
Mark Hoekveen
2019-03-18 16:45:15 +01:00
parent b314edb83f
commit 49cb8fa194
1 changed files with 93 additions and 51 deletions
Download Patch File Download Diff File Expand all files Collapse all files
Descriptor.h
+93 -51
View File
@@ -40,50 +40,50 @@ public:
//Helper functions
//TODO: Move these somewhere else. Maybe a friend-class?
double* CalculateDCT(Image* img) {
double pi = 3.14159265359;
img->type(GrayscaleType);
img->sample(Geometry("8x8!")); //64 pixels
ssize_t n = 8;
ssize_t m = 8;
Pixels view(*img);
int chan = (int)img->channels(); //should be 1, just intensity
const Quantum *p = view.getConst(0, 0, n, m); //entire image
bitset<64> retval(0);
int N = n*m;
Image* newimg = new Image(Geometry(n, m), Color("white"));
newimg->type(GrayscaleType);
Pixels conview(*newimg);
Quantum *c = conview.get(0, 0, n, m); //entire converted image
// double* CalculateDCT(Image* img) {
// double pi = 3.14159265359;
// img->type(GrayscaleType);
// img->sample(Geometry("8x8!")); //64 pixels
// ssize_t n = 8;
// ssize_t m = 8;
// Pixels view(*img);
// int chan = (int)img->channels(); //should be 1, just intensity
// const Quantum *p = view.getConst(0, 0, n, m); //entire image
// bitset<64> retval(0);
// int N = n*m;
// Image* newimg = new Image(Geometry(n, m), Color("white"));
// newimg->type(GrayscaleType);
// Pixels conview(*newimg);
// Quantum *c = conview.get(0, 0, n, m); //entire converted image
static double converted[64];
double* q = converted;
for (ssize_t j = 0; j < m; j++) {
for (ssize_t i = 0; i < n; i++) {
double sum = 0;
int k = (j*m) + i;
const Quantum *p_s = view.getConst(0, 0, n, m); //entire image
for (ssize_t x = 0; x < m; x++) {
for (ssize_t y = 0; y < n; y++) {
int n = (x*m) + y;
double pixel = ((double)p_s[0] / QuantumRange); //rescaled to [0..1]
sum += pixel * std::cos((pi / N)*(n + 0.5)*k);
p_s = p_s + chan;
}
}
q[0] = sum;
q = q++;
p = p + chan;
}
}
for (int i = 0; i < 64; i++) {
c[0] = converted[i] * 255.0;
c++;
}
delete newimg;
//newimg->write("Out.png"); //for debugging purposes
return converted;
}
// static double converted[64];
// double* q = converted;
// for (ssize_t j = 0; j < m; j++) {
// for (ssize_t i = 0; i < n; i++) {
// double sum = 0;
// int k = (j*m) + i;
// const Quantum *p_s = view.getConst(0, 0, n, m); //entire image
// for (ssize_t x = 0; x < m; x++) {
// for (ssize_t y = 0; y < n; y++) {
// int n = (x*m) + y;
// double pixel = ((double)p_s[0] / QuantumRange); //rescaled to [0..1]
// sum += pixel * std::cos((pi / N)*(n + 0.5)*k);
// p_s = p_s + chan;
// }
// }
// q[0] = sum;
// q = q++;
// p = p + chan;
// }
// }
// for (int i = 0; i < 64; i++) {
// c[0] = converted[i] * 255.0;
// c++;
// }
// delete newimg;
// //newimg->write("Out.png"); //for debugging purposes
// return converted;
// }
};
//Average color of the image.
@@ -314,17 +314,13 @@ public:
bitset<64> retval(0);
for (ssize_t j = 0; j < m; j++) {
for (ssize_t i = 0; i < n; i++) {
//LTR scanning
//cout << p[0] << " ";
if(p[0] != 0)
retval |= bitset<64>(1); //XOR
retval <<= 1;
p = p + chan;
}
//cout << endl;
}
//cout << "----" << endl << endl;
delete local_image;
return retval;
}
@@ -340,10 +336,50 @@ public:
}
};
//subclass of descriptor which has a DCT converstion function
//to be subclassed by all descriptors that use DCT.
class DCTDescriptor : public Descriptor {
public:
double* CalculateDCT(Image* pimg) {
//make a local copy of the image and convert to 8x8 grayscale:
Image* img = new Image(*pimg);
double pi = 3.14159265359;
img->type(GrayscaleType);
img->sample(Geometry("8x8!")); //64 pixels
ssize_t n = 8;
ssize_t m = 8;
int N = n*m;
//make pointers and views of the image
Pixels view(*img);
int chan = (int)img->channels(); //should be 1, just intensity
double* converted = new double[64];
for (ssize_t j = 0; j < m; j++) {
for (ssize_t i = 0; i < n; i++) {
double sum = 0;
const Quantum *p_s = view.getConst(0, 0, n, m); //entire image
int k = (i*m) + j;
for (ssize_t x = 0; x < m; x++) {
for (ssize_t y = 0; y < n; y++) {
int n = (y*m) + x;
double pixel = (((double)p_s[0] / QuantumRange)-0.5)*255; //rescaled to [-127..128]
sum += pixel * std::cos((pi / N)*(n + 0.5)*k);
p_s = p_s + chan; //next pixel
}
}
converted[k] = sum;
}
}
return converted;
}
};
//Uses an adaptive thresholding algorithm on an 8*8
//images. Re-calculates the threshold for each 2*2
//neighbourhood and stores it in a LTR map
class DCTPearson : public Descriptor {
class DCTPearson : public DCTDescriptor {
public:
bitset<64> feature(Image* img) {
Image* local_image = new Image(*img);
@@ -374,15 +410,21 @@ public:
void preview(Image* img){
Image* dct = new Image(*img);
Image* local_image = new Image(*img);
//double* converted = CalculateDCsT(dct);
double* converted = CalculateDCT(dct);
cout << "---" << endl;
for (int i = 0; i < 64; i++) {
cout << setw(11) << converted[i] << " | ";
if ( i % 8 == 7) cout << endl;
}
cout << "---" << endl;
//Write transformed image
local_image->type(GrayscaleType);
local_image->sample(Geometry("8x8!")); //64 pixels
local_image->write("DCTPearson.png");
}
};
class DCTMedian : public Descriptor {
class DCTMedian : public DCTDescriptor {
public:
bitset<64> feature(Image* img) {
Image* local_image = new Image(*img);