void triangularSmooth(unsigned char *grayImage, unsigned char *smoothImage, const int width, const int height, const float *filter, NSTimer &timer) {
NSTimer kernelTime = NSTimer("kernelTime", false, false);
kernelTime.start();
// Kernel
for ( int y = 0; y < height; y++ ) {
for ( int x = 0; x < width; x++ ) {
unsigned int filterItem = 0;
float filterSum = 0.0f;
float smoothPix = 0.0f;
for ( int fy = y - 2; fy < y + 3; fy++ ) {
for ( int fx = x - 2; fx < x + 3; fx++ ) {
if ( ((fy < 0) || (fy >= height)) || ((fx < 0) || (fx >= width)) ) {
filterItem++;
continue;
}
smoothPix += grayImage[(fy * width) + fx] * filter[filterItem];
filterSum += filter[filterItem];
filterItem++;
}
}
smoothPix /= filterSum;
smoothImage[(y * width) + x] = static_cast< unsigned char >(smoothPix);
}
}
// /Kernel
kernelTime.stop();
cout << fixed << setprecision(6);
cout << "triangularSmooth (kernel): \t" << kernelTime.getElapsed() << " seconds." << endl;
}
void contrast1D(unsigned char *grayImage, const int width, const int height, unsigned int *histogram, const unsigned int HISTOGRAM_SIZE, const unsigned int CONTRAST_THRESHOLD, NSTimer &timer) {
unsigned int i = 0;
NSTimer kernelTime = NSTimer("kernelTime", false, false);
while ( (i < HISTOGRAM_SIZE) && (histogram[i] < CONTRAST_THRESHOLD) ) {
i++;
}
unsigned int min = i;
i = HISTOGRAM_SIZE - 1;
while ( (i > min) && (histogram[i] < CONTRAST_THRESHOLD) ) {
i--;
}
unsigned int max = i;
float diff = max - min;
kernelTime.start();
// Kernel
for ( int y = 0; y < height; y++ ) {
for (int x = 0; x < width; x++ ) {
unsigned char pixel = grayImage[(y * width) + x];
if ( pixel < min ) {
pixel = 0;
}
else if ( pixel > max ) {
pixel = 255;
}
else {
pixel = static_cast< unsigned char >(255.0f * (pixel - min) / diff);
}
grayImage[(y * width) + x] = pixel;
}
}
// /Kernel
kernelTime.stop();
cout << fixed << setprecision(6);
cout << "contrast1D (kernel): \t\t" << kernelTime.getElapsed() << " seconds." << endl;
}
void histogram1D(unsigned char *grayImage, unsigned char *histogramImage, const int width, const int height, unsigned int *histogram, const unsigned int HISTOGRAM_SIZE, const unsigned int BAR_WIDTH, NSTimer &timer) {
unsigned int max = 0;
NSTimer kernelTime = NSTimer("kernelTime", false, false);
memset(reinterpret_cast< void * >(histogram), 0, HISTOGRAM_SIZE * sizeof(unsigned int));
kernelTime.start();
// Kernel
for ( int y = 0; y < height; y++ ) {
for ( int x = 0; x < width; x++ ) {
histogram[static_cast< unsigned int >(grayImage[(y * width) + x])] += 1;
}
}
// /Kernel
kernelTime.stop();
for ( unsigned int i = 0; i < HISTOGRAM_SIZE; i++ ) {
if ( histogram[i] > max ) {
max = histogram[i];
}
}
for ( int x = 0; x < HISTOGRAM_SIZE * BAR_WIDTH; x += BAR_WIDTH ) {
unsigned int value = HISTOGRAM_SIZE - ((histogram[x / BAR_WIDTH] * HISTOGRAM_SIZE) / max);
for ( unsigned int y = 0; y < value; y++ ) {
for ( unsigned int i = 0; i < BAR_WIDTH; i++ ) {
histogramImage[(y * HISTOGRAM_SIZE * BAR_WIDTH) + x + i] = 0;
}
}
for ( unsigned int y = value; y < HISTOGRAM_SIZE; y++ ) {
for ( unsigned int i = 0; i < BAR_WIDTH; i++ ) {
histogramImage[(y * HISTOGRAM_SIZE * BAR_WIDTH) + x + i] = 255;
}
}
}
cout << fixed << setprecision(6);
cout << "histogram1D (kernel): \t\t" << kernelTime.getElapsed() << " seconds." << endl;
}
void rgb2gray(unsigned char *inputImage, unsigned char *grayImage, const int width, const int height, NSTimer &timer) {
NSTimer kernelTime = NSTimer("kernelTime", false, false);
kernelTime.start();
// Kernel
for ( int y = 0; y < height; y++ ) {
for ( int x = 0; x < width; x++ ) {
float grayPix = 0.0f;
float r = static_cast< float >(inputImage[(y * width) + x]);
float g = static_cast< float >(inputImage[(width * height) + (y * width) + x]);
float b = static_cast< float >(inputImage[(2 * width * height) + (y * width) + x]);
grayPix = (0.3f * r) + (0.59f * g) + (0.11f * b);
grayImage[(y * width) + x] = static_cast< unsigned char >(grayPix);
}
}
// /Kernel
kernelTime.stop();
cout << fixed << setprecision(6);
cout << "rgb2gray (kernel): \t\t" << kernelTime.getElapsed() << " seconds." << endl;
}
int main(int argc, char *argv[]) {
NSTimer total = NSTimer("total", false, false);
if ( argc != 2 ) {
cerr << "Usage: " << argv[0] << " <filename>" << endl;
return 1;
}
// Load the input image
CImg< unsigned char > inputImage = CImg< unsigned char >(argv[1]);
if ( displayImages ) {
inputImage.display("Input Image");
}
if ( inputImage.spectrum() != 3 ) {
cerr << "The input must be a color image." << endl;
return 1;
}
// Image is loaded, start timing
total.start();
// Convert the input image to grayscale
CImg< unsigned char > grayImage = CImg< unsigned char >(inputImage.width(), inputImage.height(), 1, 1);
rgb2gray(inputImage.data(), grayImage.data(), inputImage.width(), inputImage.height(), total);
total.stop();
if ( displayImages ) {
grayImage.display("Grayscale Image");
}
if ( saveAllImages ) {
grayImage.save("./grayscale.bmp");
}
total.start();
// Compute 1D histogram
CImg< unsigned char > histogramImage = CImg< unsigned char >(BAR_WIDTH * HISTOGRAM_SIZE, HISTOGRAM_SIZE, 1, 1);
unsigned int *histogram = new unsigned int [HISTOGRAM_SIZE];
histogram1D(grayImage.data(), histogramImage.data(), grayImage.width(), grayImage.height(), histogram, HISTOGRAM_SIZE, BAR_WIDTH, total);
total.stop();
if ( displayImages ) {
histogramImage.display("Histogram");
}
if ( saveAllImages ) {
histogramImage.save("./histogram.bmp");
}
total.start();
// Contrast enhancement
contrast1D(grayImage.data(), grayImage.width(), grayImage.height(), histogram, HISTOGRAM_SIZE, CONTRAST_THRESHOLD, total);
total.stop();
if ( displayImages ) {
grayImage.display("Contrast Enhanced Image");
}
if ( saveAllImages ) {
grayImage.save("./contrast.bmp");
}
total.start();
delete [] histogram;
// Triangular smooth (convolution)
CImg< unsigned char > smoothImage = CImg< unsigned char >(grayImage.width(), grayImage.height(), 1, 1);
triangularSmooth(grayImage.data(), smoothImage.data(), grayImage.width(), grayImage.height(), filter, total);
// Job done, stop timing
total.stop();
if ( displayImages ) {
smoothImage.display("Smooth Image");
}
smoothImage.save("./smooth.bmp");
// Wrap up
cout << fixed << setprecision(6) << endl;
cout << "Execution time: \t\t" << total.getElapsed() << " seconds." << endl << endl;
return 0;
}