151 lines
5.1 KiB
C++
151 lines
5.1 KiB
C++
|
|
#include <sys/time.h> /* gettimeofday() */
|
|
#include <omp.h>
|
|
#include <iostream>
|
|
#include <string.h>
|
|
#include <stdlib.h>
|
|
#include "BMP.h"
|
|
using namespace std;
|
|
|
|
void usage(const char * progName);
|
|
void squashAndPadData(unsigned char * raw_data, unsigned char * padded_data,
|
|
int width, int height);
|
|
void applyEdgeDetection(unsigned char * padded_data, unsigned char * edge_data,
|
|
int width, int height, int threshold);
|
|
|
|
/**************************************************************************
|
|
* Print some basic usage information for the program *
|
|
*************************************************************************/
|
|
void usage(const char * progName)
|
|
{
|
|
cout << "Usage: " << progName << " [options] <input-BMP-file>" << endl;
|
|
cout << " Options:" << endl;
|
|
cout << " -l level : apply threshold at level" << endl;
|
|
exit(42);
|
|
}
|
|
|
|
/**************************************************************************
|
|
* The main method is the entry point of our program *
|
|
*************************************************************************/
|
|
int main(int argc, char * argv[])
|
|
{
|
|
int argi;
|
|
string inputFileName;
|
|
string outputFileName;
|
|
int threshold_level = -1;
|
|
|
|
for (argi = 0; argi < argc; argi++)
|
|
{
|
|
if (!strcmp(argv[argi], "-l"))
|
|
{
|
|
if (argi >= argc - 1)
|
|
usage(argv[0]);
|
|
argi++;
|
|
threshold_level = atoi(argv[argi]);
|
|
}
|
|
else
|
|
{
|
|
inputFileName = argv[argi];
|
|
outputFileName = string(argv[argi], strlen(argv[argi]) - 4);
|
|
outputFileName += "-edges.bmp";
|
|
}
|
|
}
|
|
|
|
if (inputFileName == "")
|
|
usage(argv[0]);
|
|
|
|
BMP inputImage(inputFileName.c_str());
|
|
int width = inputImage.getWidth();
|
|
int height = inputImage.getHeight();
|
|
int num_pixels = width * height;
|
|
unsigned char * bmp_data =
|
|
new unsigned char[num_pixels * 3];
|
|
inputImage.read(bmp_data);
|
|
|
|
unsigned char * padded_data =
|
|
new unsigned char[(width + 2) * (height + 2)];
|
|
squashAndPadData(bmp_data, padded_data, width, height);
|
|
delete[] bmp_data;
|
|
|
|
unsigned char * edge_data = new unsigned char[width * height * 3];
|
|
|
|
struct timeval before, after;
|
|
gettimeofday(&before, NULL); /* Start timing */
|
|
|
|
applyEdgeDetection(padded_data, edge_data, width, height, threshold_level);
|
|
|
|
gettimeofday(&after, NULL); /* Stop timing */
|
|
|
|
/* Write the output BMP image */
|
|
BMP outputImage(outputFileName.c_str(),
|
|
width,
|
|
height,
|
|
edge_data);
|
|
|
|
double time_before = before.tv_sec + before.tv_usec / 1000000.0;
|
|
double time_after = after.tv_sec + after.tv_usec / 1000000.0;
|
|
double diff = time_after - time_before;
|
|
cout << "Elapsed time: " << diff << " seconds." << endl;
|
|
|
|
delete[] padded_data;
|
|
delete[] edge_data;
|
|
}
|
|
|
|
/**************************************************************************
|
|
* Convert the 24-bpp BMP data pointed to by raw_data to a 8-bpp *
|
|
* grayscale representation *
|
|
*************************************************************************/
|
|
void squashAndPadData(unsigned char * raw_data, unsigned char * padded_data,
|
|
int width, int height)
|
|
{
|
|
for (int i = 0; i < width + 2; i++)
|
|
*padded_data++ = 0;
|
|
for (int i = 0; i < height; i++)
|
|
{
|
|
*padded_data++ = 0;
|
|
for (int j = 0; j < width; j++)
|
|
{
|
|
*padded_data++ = (raw_data[0] + raw_data[1] + raw_data[2]) / 3;
|
|
raw_data += 3;
|
|
}
|
|
*padded_data++ = 0;
|
|
}
|
|
for (int i = 0; i < width + 2; i++)
|
|
*padded_data++ = 0;
|
|
}
|
|
|
|
/**************************************************************************
|
|
* Apply the actual edge detection algorithm on the grayscale data *
|
|
*************************************************************************/
|
|
void applyEdgeDetection(unsigned char * padded_data, unsigned char * edge_data,
|
|
int width, int height, int threshold)
|
|
{
|
|
unsigned char (*in)[height+2][width+2] =
|
|
(unsigned char (*)[height+2][width+2]) padded_data;
|
|
unsigned char (*out)[height][width][3] =
|
|
(unsigned char (*)[height][width][3]) edge_data;
|
|
#pragma omp parallel for
|
|
for (int y = 0; y < height; y++)
|
|
{
|
|
for (int x = 0; x < width; x++)
|
|
{
|
|
/* Apply the Sobel operator on the in to
|
|
* produce an out value. */
|
|
int gradY = (*in)[y][x] + 2 * (*in)[y][x+1] + (*in)[y][x+2]
|
|
- (*in)[y+2][x] - 2 * (*in)[y+2][x+1] - (*in)[y+2][x+2];
|
|
int gradX = (*in)[y][x+2] + 2 * (*in)[y+1][x+2] + (*in)[y+2][x+2]
|
|
- (*in)[y][x] - 2 * (*in)[y+1][x] - (*in)[y+2][x];
|
|
int grad = gradX + gradY;
|
|
if (grad < 0)
|
|
grad = 0;
|
|
else if (grad > 255)
|
|
grad = 255;
|
|
if (threshold >= 0)
|
|
grad = grad < threshold ? 0 : 255;
|
|
(*out)[y][x][0] = grad;
|
|
(*out)[y][x][1] = grad;
|
|
(*out)[y][x][2] = grad;
|
|
}
|
|
}
|
|
}
|