122 lines
3.7 KiB
C++
122 lines
3.7 KiB
C++
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#include <iostream>
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#include <string.h>
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#include <stdlib.h>
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#include "BMP.h"
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using namespace std;
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void usage(const char * progName);
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void squashAndPadData(unsigned char * raw_data, unsigned char * padded_data,
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int width, int height);
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void applyEdgeDetection(unsigned char * padded_data, unsigned char * edge_data,
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int width, int height, int threshold);
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void usage(const char * progName)
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{
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cout << "Usage: " << progName << " [options] <input-BMP-file>" << endl;
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cout << " Options:" << endl;
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cout << " -l level : apply threshold at level" << endl;
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exit(42);
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}
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int main(int argc, char * argv[])
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{
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int argi;
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string inputFileName;
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string outputFileName;
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int threshold_level = -1;
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for (argi = 0; argi < argc; argi++)
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{
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if (!strcmp(argv[argi], "-l"))
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{
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if (argi >= argc - 1)
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usage(argv[0]);
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argi++;
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threshold_level = atoi(argv[argi]);
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}
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else
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{
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inputFileName = argv[argi];
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outputFileName = string(argv[argi], strlen(argv[argi]) - 4);
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outputFileName += "-edges.bmp";
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}
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}
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if (inputFileName == "")
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usage(argv[0]);
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BMP inputImage(inputFileName.c_str());
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int width = inputImage.getWidth();
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int height = inputImage.getHeight();
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int num_pixels = width * height;
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unsigned char * bmp_data =
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new unsigned char[num_pixels * 3];
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inputImage.read(bmp_data);
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unsigned char * padded_data =
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new unsigned char[(width + 2) * (height + 2)];
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squashAndPadData(bmp_data, padded_data, width, height);
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delete[] bmp_data;
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unsigned char * edge_data = new unsigned char[width * height * 3];
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applyEdgeDetection(padded_data, edge_data, width, height, threshold_level);
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BMP outputImage(outputFileName.c_str(),
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width,
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height,
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edge_data);
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delete[] padded_data;
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delete[] edge_data;
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}
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void squashAndPadData(unsigned char * raw_data, unsigned char * padded_data,
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int width, int height)
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{
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for (int i = 0; i < width + 2; i++)
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*padded_data++ = 0;
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for (int i = 0; i < height; i++)
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{
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*padded_data++ = 0;
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for (int j = 0; j < width; j++)
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{
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*padded_data++ = (raw_data[0] + raw_data[1] + raw_data[2]) / 3;
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raw_data += 3;
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}
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*padded_data++ = 0;
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}
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for (int i = 0; i < width + 2; i++)
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*padded_data++ = 0;
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}
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void applyEdgeDetection(unsigned char * padded_data, unsigned char * edge_data,
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int width, int height, int threshold)
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{
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unsigned char (*in)[height+2][width+2] =
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(unsigned char (*)[height+2][width+2]) padded_data;
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unsigned char (*out)[height][width][3] =
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(unsigned char (*)[height][width][3]) edge_data;
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for (int y = 0; y < height; y++)
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{
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for (int x = 0; x < width; x++)
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{
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/* Apply the Sobel operator on the in to
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* produce an out value. */
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int gradY = (*in)[y][x] + 2 * (*in)[y][x+1] + (*in)[y][x+2]
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- (*in)[y+2][x] - 2 * (*in)[y+2][x+1] - (*in)[y+2][x+2];
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int gradX = (*in)[y][x+2] + 2 * (*in)[y+1][x+2] + (*in)[y+2][x+2]
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- (*in)[y][x] - 2 * (*in)[y+1][x] - (*in)[y+2][x];
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int grad = gradX + gradY;
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if (grad < 0)
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grad = 0;
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else if (grad > 255)
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grad = 255;
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if (threshold >= 0)
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grad = grad < threshold ? 0 : 255;
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(*out)[y][x][0] = grad;
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(*out)[y][x][1] = grad;
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(*out)[y][x][2] = grad;
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}
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}
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}
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