C语言实现BMP图像处理（边缘检测）

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以Sobel算子为例，其余模板算子卷积代码部分同Sobel算子。如：高斯算子、拉普拉斯算子等

#include <stdio.h>
#include <stdlib.h>
#include <Windows.h>
#include <math.h>

int main(int* argc, char** argv)
{
	FILE* fp = fopen("./01.bmp", "rb");
	if (fp == 0)
		return 0;
	BITMAPFILEHEADER fileHead;
	fread(&fileHead, sizeof(BITMAPFILEHEADER), 1, fp);

	BITMAPINFOHEADER infoHead;
	fread(&infoHead, sizeof(BITMAPINFOHEADER), 1, fp);
	int width = infoHead.biWidth;
	int height = infoHead.biHeight;
	int biCount = infoHead.biBitCount;

	int lineByte = (biCount*width / 8 + 3) / 4 * 4;
	RGBQUAD* pColorTable;
	pColorTable = new RGBQUAD[256];
	fread(pColorTable, sizeof(RGBQUAD), 256, fp);

	unsigned char* pBmpBuf;
	pBmpBuf = new unsigned char[lineByte*height];
	fread(pBmpBuf, lineByte*height, 1, fp);
	fclose(fp);

	// 新图
	FILE* fop = fopen("sobel.bmp", "wb");
	if (fop == 0)
		return 0;
	unsigned char *pBmpBuf2;
	// 初始化
	pBmpBuf2 = new unsigned char[lineByte*height];
	for (int i = 0; i < height; ++i){
		for (int j = 0; j < width; ++j){
			*(pBmpBuf2 + i*lineByte + j) = *(pBmpBuf + i*lineByte + j);
		}
	}


	int ul, uc, ur, dl, dc, dr;
	int lu, lc, ld, ru, rc, rd;
	double hir, vec;
	for (int i = 1; i < height - 1; ++i){
		for (int j = 1; j < width - 1; ++j){
			// 垂直梯度算子：检测水平边缘
			vec = 0;
			ul = *(pBmpBuf + (i + 1)*lineByte + (j - 1))*(-1);
			uc = *(pBmpBuf + (i + 1)*lineByte + j)*(-2);
			ur = *(pBmpBuf + (i + 1)*lineByte + j)*(-1);
			dl = *(pBmpBuf + (i - 1)*lineByte + (j - 1)) * 1;
			dc = *(pBmpBuf + (i - 1)*lineByte + j) * 2;
			dr = *(pBmpBuf + (i - 1)*lineByte + j) * 1;
			vec = ul + uc + ur + dl + dc + dr;
			// 水平梯度算子：检测垂直边缘
			hir = 0;
			lu = *(pBmpBuf + (i + 1)*lineByte + (j - 1))*(-1);
			lc = *(pBmpBuf + (i - 0)*lineByte + (j - 1))*(-2);
			ld = *(pBmpBuf + (i - 1)*lineByte + (j - 1))*(-1);
			ru = *(pBmpBuf + (i + 1)*lineByte + (j + 1)) * 1;
			rc = *(pBmpBuf + (i - 0)*lineByte + (j + 1)) * 2;
			rd = *(pBmpBuf + (i - 1)*lineByte + (j + 1)) * 1;
			hir = lu + lc + ld + ru + rc + rd;
			*(pBmpBuf2+i*lineByte+j) = round(sqrt(hir*hir + vec*vec));
		}
	}

	fwrite(&fileHead, sizeof(BITMAPFILEHEADER), 1, fop);
	fwrite(&infoHead, sizeof(BITMAPINFOHEADER), 1, fop);
	fwrite(pColorTable, sizeof(RGBQUAD), 256, fop);
	fwrite(pBmpBuf2, lineByte*height, 1, fop);
	fclose(fop);

	system("pause");
	return 0;
}

实验结果：

           原图                             效果图

         

实验结果分析：边缘检测是采用计算梯度的方式进行计算。注意边缘有一圈白色的，产生原因是没有对图像最外圈像素处理。