Files
small-image-descriptors/Descriptor.h
T
2019-06-30 00:28:08 +02:00

388 lines
10 KiB
C++

#pragma once
#include <string>
#include <boost/filesystem.hpp>
#include <Magick++.h>
#include <bitset> //in which we store our feature vectors
#include <algorithm> //for sorting
using namespace std;
using namespace Magick;
namespace fs = boost::filesystem;
//Virtual base class
//Holds definitions for all common functions of descriptors,
//but should be overloaded by a child class
class Descriptor {
public:
virtual uint64_t feature(Image* img) = 0;
//Interpret the bitsets as integers and calculate their distance.
virtual uint64_t distance(uint64_t a, uint64_t b) {
return abs((int64_t)(a - b));
};
virtual string ToString() = 0;
virtual fs::path ToPath() {
return fs::path(this->ToString());
}
//should return true if a > b
virtual bool bigger(uint64_t a, uint64_t b) {
return true;
}
//Function which should output some example(s) to file
//that show how this descriptor works.
virtual void preview(Image* img) {
cout << "No preview defined. :-( " << endl;
}
};
//Average color of the image.
//the least significant 24 bits of the feature represent
//the color intensity of the average color in RGB
//with 8 bits per color.
class averageColor : public Descriptor {
public:
uint64_t feature(Image* img) {
ssize_t n = img->columns();
ssize_t m = img->rows();
Pixels view(*img);
const Quantum *p = view.getConst(0, 0, n, m); //entire image
uint64_t red = 0, green = 0, blue = 0;
float numpixels = (float)(n*m);
if (img->channels() < 3) return 0;
for (ssize_t j = 0; j < m; j++) {
for (ssize_t i = 0; i < n; i++) {
//LTR scanning
red += p[0];
green += p[1];
blue += p[2];
p = p + 3;
}
}
//get the color values.. implicit cast to int
int r = ((red/numpixels) / QuantumRange) * 255;
int g = ((green/numpixels) / QuantumRange) * 255;
int b = ((blue/numpixels) / QuantumRange) * 255;
//now store all this into a bitset.. assuming 8 bits per color, if everything went correctly.. which we should check.. probably..
uint64_t retval = r;
retval <<= 8;
retval += g;
retval <<= 8;
retval += b;
return retval;
}
uint64_t distance(uint64_t a, uint64_t b) {
//do some bit shifting magic to get ints back
int red_a = (a >> 16);
int green_a = (a << (64-16) >> (64-8));
int blue_a = (a << (64-8) >> (64-8));
int red_b = (b >> 16);
int green_b = (b << (64 - 16) >> (64 - 8));
int blue_b = (b << (64 - 8) >> (64 - 8));
return abs(red_a - red_b) + abs(green_a - green_b) + abs(blue_a - blue_b);
}
string ToString() {
return "averageColor";
}
};
//Counts the total number of colors
//and stores it in bit representation.
//Upper limit 16777216
//Only uses least significant 24 bits
class numColors : public Descriptor {
public:
uint64_t feature(Image* img) {
return img->totalColors()-1;
}
string ToString() {
return "numColors";
}
};
//Median descriptor. See relevant literature.
//Stores a map of the image (LTR scanned) with 1 iff
//higher than median and 0 otherwise.
class median : public Descriptor {
public:
uint64_t feature(Image* img) {
Image* local_image = new Image(*img);
local_image->type(GrayscaleType);
local_image->sample(Geometry("8x8!")); //64 pixels
ssize_t n = 8;
ssize_t m = 8;
Pixels view(*local_image);
float intensity = 0;
int numpixels = (int)(n*m);
const Quantum *p = view.getConst(0, 0, n, m); //entire image
int* intensities = new int[numpixels];
int index = 0;
int chan = (int)local_image->channels(); //should be 1, for a grayscale img
for (ssize_t j = 0; j < m; j++) {
for (ssize_t i = 0; i < n; i++) {
//LTR scanning
intensities[index] = p[0];
p = p + chan;
index++;
}
}
//Calculate median:
sort(intensities, intensities + numpixels);
//We know where the median is going to be:
intensity = (float)(intensities[31] + intensities[32]) / 2;
uint64_t retval = 0;
const Quantum *q = view.getConst(0, 0, n, m); //entire image
for (ssize_t j = 0; j < m; j++) {
for (ssize_t i = 0; i < n; i++) {
retval <<= 1;
if (q[0] > intensity)
retval++;
q = q + local_image->channels();
}
}
delete local_image;
delete intensities;
return retval;
}
uint64_t distance(uint64_t a, uint64_t b) {
return (uint64_t)__builtin_popcountll(a^b);
}
string ToString() {
return "median";
}
};
//Sobel descriptor
//Calculates average intensity of the image with
//sobel convolution applied in both directions
class sobel : public Descriptor {
public:
uint64_t feature(Image* img) {
Image* local_image = new Image(*img);
//TODO: Some preprocessing for this?
//img->reduceNoise(4.0);
local_image->type(GrayscaleType);
//Apply sobel convolution
local_image->convolve(3, sobelX);
local_image->convolve(3, sobelY);
ssize_t n = local_image->rows();
ssize_t m = local_image->columns();
Pixels view(*local_image);
const Quantum *p = view.getConst(0, 0, m, n); //entire image
uint64_t intensity = 0;
int chan = (int)local_image->channels();
for (ssize_t j = 0; j < m; j++) {
for (ssize_t i = 0; i < n; i++) {
//LTR scanning
intensity += p[0];
//cout << p[0] << " ";
p = p + chan;
}
//cout << endl;
}
uint64_t scaledIntensity = ((float)(intensity / (n*m)) / QuantumRange) * 255;
delete local_image;
return scaledIntensity;
}
string ToString() {
return "sobel";
}
private:
const double sobelX[9] = { 1, 0, -1, 2, 0, -2, 1, 0, -1 };
const double sobelY[9] = { 1, 2, 1, 0, 0, 0, -1, -2, -1 };
};
//Pearson code
//Creates a map of the 8*8 image which has 1
//iff the pixel is higher than the next pixel,
//0 otherwise
class pearson : public Descriptor {
public:
uint64_t feature(Image* img) {
Image* local_image = new Image(*img);
local_image->type(GrayscaleType);
local_image->sample(Geometry("8x8!")); //64 pixels
ssize_t n = 8;
ssize_t m = 8;
Pixels view(*local_image);
int chan = (int)local_image->channels();
const Quantum *p = view.getConst(0, 0, n, m); //entire image
uint64_t retval = 0;
int prev = p[0]; //so we always start with a 0
for (ssize_t j = 0; j < m; j++) {
for (ssize_t i = 0; i < n; i++) {
//LTR scanning
//NOTE: Scanning order might be quite relevant for this descriptor
int cur = p[0];
if(prev < cur) retval++;
retval <<= 1;
p = p + chan;
prev = cur;
}
}
delete local_image;
return retval;
}
uint64_t distance(uint64_t a, uint64_t b) {
return (uint64_t)__builtin_popcountll(a^b);
}
string ToString() {
return "pearson";
}
};
//Uses an adaptive thresholding algorithm on an 8*8
//images. Re-calculates the threshold for each
//neighbourhood and stores it in a LTR map
class threshold : public Descriptor {
public:
uint64_t feature(Image* img) {
Image* local_image = new Image(*img);
local_image->type(GrayscaleType);
local_image->sample(Geometry("8x8!")); //64 pixels
local_image->adaptiveThreshold(3, 3); //Thresholding in a moving neighborhood
ssize_t n = 8;
ssize_t m = 8;
Pixels view(*local_image);
int chan = (int)local_image->channels();
const Quantum *p = view.getConst(0, 0, n, m); //entire image
uint64_t retval = 0;
for (ssize_t j = 0; j < m; j++) {
for (ssize_t i = 0; i < n; i++) {
if(p[0] != 0) retval++;
retval <<= 1;
p = p + chan;
}
}
delete local_image;
return retval;
}
uint64_t distance(uint64_t a, uint64_t b) {
return (uint64_t)__builtin_popcountll(a^b);
}
string ToString() {
return "threshold";
}
};
//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;
}
}
delete img;
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 DCTDescriptor {
public:
uint64_t feature(Image* img) {
Image* local_image = new Image(*img);
double* converted = CalculateDCT(local_image);
double prev = 0;
uint64_t retval = 0;
for (int i = 0; i < 64; i++) {
if (converted[i] > prev) retval++;
retval <<= 1;
prev = converted[i];
}
delete local_image;
return retval;
}
uint64_t distance(uint64_t a, uint64_t b) {
return (uint64_t)__builtin_popcountll(a^b);
}
string ToString() {
return "DCTPearson";
}
void preview(Image* img){
Image* dct = new Image(*img);
Image* local_image = new Image(*img);
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 DCTDescriptor {
public:
uint64_t feature(Image* img) {
Image* local_image = new Image(*img);
double* converted = CalculateDCT(local_image);
double bullshit[64];
for (ssize_t i = 0; i < 64; i++) {
bullshit[i] = converted[i];
}
sort(bullshit, bullshit + 64);
float median = (float)(bullshit[31] + bullshit[32]) / 2;
uint64_t retval = 0;
for (ssize_t i = 0; i < 64; i++) {
retval <<= 1;
if (converted[i] > median) retval++;
}
delete local_image;
return retval;
}
uint64_t distance(uint64_t a, uint64_t b) {
return (uint64_t)__builtin_popcountll(a^b);
}
string ToString() {
return "DCTMedian";
}
};