图像增强处理-直方图均衡化与规定化

本方法用c/cpp实现，不依赖于opencv库

0.0.1. BMP图像读取：

  • _hxlbmp.h
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#ifndef hxlbmpfiledll_H
#define hxlbmpfiledll_H
#define _CRT_SECURE_NO_WARNINGS
#include <windows.h>
#include <math.h>
#include <stdio.h>

#ifdef BUILD_HXL_DLL
#define EXPORT __declspec(dllexport)
#else
#define EXPORT __declspec(dllimport)
#endif

class EXPORT HXLBMPFILE
{
  BYTE *Imagedata;

public:
  int imagew, imageh;
  int iYRGBnum;	//1 if grey; 3 if color
  RGBQUAD palette[256];

  BYTE *pDataAt(int h, int Y0R0G1B2 = 0);
  BOOL AllocateMem();

  BOOL LoadBMPFILE(char *fname);
  BOOL SaveBMPFILE(char *fname);

  HXLBMPFILE();
  ~HXLBMPFILE();
};
#endif

  • _hxlbmp.cpp
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#define BUILD_HXL_DLL
#include "_hxlbmp.h"

HXLBMPFILE::HXLBMPFILE() 
{
	Imagedata = NULL;

	for (int i = 0; i < 256; i++)
	{
		palette[i].rgbBlue =
			palette[i].rgbGreen =
				palette[i].rgbRed = i;	
		palette[i].rgbReserved = 0;
	}

	iYRGBnum = 0;
	imagew = imageh = 0;
}

HXLBMPFILE::~HXLBMPFILE() 
{
	if (Imagedata)
		delete[] Imagedata;
}

BYTE *HXLBMPFILE::pDataAt(int h, int Y0R0G1B2)
{
	if (iYRGBnum <= Y0R0G1B2) 
		return NULL;
	int w = imagew * h + Y0R0G1B2 * imageh * imagew;
	return Imagedata + w;
}

BOOL HXLBMPFILE::AllocateMem()
{
	int w = imagew * imageh * iYRGBnum;

	if (Imagedata)
	{
		delete[] Imagedata;
		Imagedata = NULL;
	}

	Imagedata = new BYTE[w];

	if (Imagedata)
		memset(Imagedata, 0, w);
	return (Imagedata != NULL);
}

BOOL HXLBMPFILE::LoadBMPFILE(char *cFilename)
{
	FILE *f;
	if (strlen(cFilename) < 1)
		return FALSE;

	f = fopen(cFilename, "r+b");
	if (f == NULL)
		return FALSE;

	BITMAPFILEHEADER fh;
	BITMAPINFOHEADER ih;

	fread(&fh, sizeof(BITMAPFILEHEADER), 1, f);
	if (fh.bfType != 0x4d42) //"BM"
	{
		fclose(f);
		return FALSE;
	}

	fread(&ih, sizeof(BITMAPINFOHEADER), 1, f);
	if ((ih.biBitCount != 8) && (ih.biBitCount != 24))
	{
		fclose(f);
		return FALSE;
	}
	printf("ih.biBitCount = %d",ih.biBitCount);
	iYRGBnum = ih.biBitCount / 8;
	imagew = ih.biWidth;
	imageh = ih.biHeight;

	if (!AllocateMem())
	{
		fclose(f);
		return FALSE;
	}

	if (iYRGBnum == 1)
		fread(palette, sizeof(RGBQUAD), 256, f);

	fseek(f, fh.bfOffBits, SEEK_SET);

	int w4b = (imagew * iYRGBnum + 3) / 4 * 4, i, j;
	BYTE *ptr;

	ptr = new BYTE[w4b];
	if (iYRGBnum == 1)
	{
		for (i = imageh - 1; i >= 0; i--)
		{
			fread(ptr, w4b, 1, f);
			memmove(pDataAt(i), ptr, imagew);
		}
	}
	if (iYRGBnum == 3)
	{
		for (i = imageh - 1; i >= 0; i--)
		{
			fread(ptr, w4b, 1, f);
			for (j = 0; j < imagew; j++)
			{
				*(pDataAt(i, 0) + j) = *(ptr + j * 3 + 2);
				*(pDataAt(i, 1) + j) = *(ptr + j * 3 + 1);
				*(pDataAt(i, 2) + j) = *(ptr + j * 3 + 0);
			}
		}
	}
	delete[] ptr;
	fclose(f);
	return TRUE;
}

BOOL HXLBMPFILE::SaveBMPFILE(char *cFilename)
{
	if (!Imagedata)
		return FALSE;
	FILE *f;
	if (strlen(cFilename) < 1)
		return FALSE;
	f = fopen(cFilename, "w+b");
	if (f == NULL)
		return FALSE;

	BITMAPFILEHEADER fh;
	BITMAPINFOHEADER ih;
	memset(&ih, 0, sizeof(BITMAPINFOHEADER));
	/*--headers--*/
	fh.bfType = 0x4d42;
	fh.bfReserved1 = fh.bfReserved2 = 0;
	fh.bfOffBits = sizeof(LPBITMAPFILEHEADER) +
				   sizeof(BITMAPINFOHEADER) +
				   ((iYRGBnum == 1) ? 256 * sizeof(RGBQUAD) : 0);

	ih.biSize = 40;
	ih.biPlanes = 1;
	ih.biWidth = imagew;
	ih.biHeight = imageh;
	ih.biBitCount = 8 * iYRGBnum;

	int w4b = (imagew * iYRGBnum + 3) / 4 * 4;
	ih.biSizeImage = ih.biHeight * w4b;
	fh.bfSize = fh.bfOffBits + ih.biSizeImage;

	fwrite(&fh, sizeof(BITMAPFILEHEADER), 1, f);
	fwrite(&ih, sizeof(BITMAPINFOHEADER), 1, f);
	/*palette*/
	if (iYRGBnum == 1)
		fwrite(palette, sizeof(RGBQUAD), 256, f);
	
	BYTE *ptr;
	int i, j;
	ptr = new BYTE[w4b];
	memset(ptr, 0, w4b);
	if (iYRGBnum == 1)
	{
		for (i = ih.biHeight - 1; i >= 0; i--)
		{
			memmove(ptr, pDataAt(i), ih.biWidth);
			fwrite(ptr, w4b, 1, f);
		}
	}
	if (iYRGBnum == 3)
	{
		for (i = ih.biHeight - 1; i >= 0; i--)
		{
			for (j = 0; j < ih.biWidth; j++)
			{
				*(ptr + j * 3 + 0) = *(pDataAt(i, 2) + j);
				*(ptr + j * 3 + 1) = *(pDataAt(i, 1) + j);
				*(ptr + j * 3 + 2) = *(pDataAt(i, 0) + j);
			}
			fwrite(ptr, w4b, 1, f);
		}
	}
	delete[] ptr;
	fclose(f);
	return TRUE;
}
int main()
{
	HXLBMPFILE bmp;
	char Load_Addr[] = { "1.bmp" };
	char Save_Addr[] = { "result.bmp" };
	if (!bmp.LoadBMPFILE(Load_Addr))
	{
		return 1;
	}
	HXLBMPFILE bf;
	bf.imagew = bmp.imagew;
	bf.imageh = bmp.imageh;
	bf.iYRGBnum = bmp.iYRGBnum; 

	if (!bf.AllocateMem())
	{
		return 1;
	}
	for (int i = 0; i < bmp.imageh; i++)
		for (int j = 0; j < bmp.imagew; j++)
		{
			bf.pDataAt(i)[j] = bmp.pDataAt(i)[j];
		}
	if (bf.SaveBMPFILE(Save_Addr))
	{
		return 1;
	}
}

0.0.2. 直方图均衡化

  1. 获取图像直方图：
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int* GetHistagram(HXLBMPFILE* bmp)
{
	int* ptrHistagram = new int[256];
	memset(ptrHistagram, 0, sizeof(ptrHistagram));
	for (int i = 0; i < (*bmp).imageh; i++)
		for (int j = 0; j < (*bmp).imagew; j++)
		{
			ptrHistagram[((*bmp).pDataAt(i)[j])] ++;
		}
	return ptrHistagram;
}
  1. 获取累计直方图：
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double* GetGAddHistagram(int* ptrHistagram, int w)
{
	double* ptrGAgram = new double[256];
	memset(ptrGAgram, 0, sizeof(ptrGAgram));
	ptrGAgram[0] = ptrHistagram[0] / double(w);
	for (int i = 1; i < 256; i++)
	{
		ptrGAgram[i] = (ptrHistagram[i] / double(w) + ptrGAgram[i - 1]);
	}
	return ptrGAgram;
}
  1. 获取均衡化：
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int* EquHistagram(double* ptrGAgram)
{
	int* ptrEqgram = new int[256];
	memset(ptrEqgram, 0, sizeof(ptrEqgram));
	for (int i = 0; i < 256; i++)
		ptrEqgram[i] = 255 * int(ptrGAgram[i]);
	return ptrEqgram;
}

​ 直方图均衡化实质上就是一个LUT，将原有灰度值变换到新的灰度值，由此增强图像对比度

0.0.3. 直方图规定化

  • 获取规定化图像的直方图（如上1）
    • 如给定直方图曲线：
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int* getHistagram(int w)
{
	double* temp = new double[256];
	int* ptrHistagram = new int[256];
	memset(ptrHistagram, 0, sizeof(ptrHistagram));
	memset(temp,0,sizeof(temp));
	double count = 0;
	for (int i = 0; i < 256; i++)
	{
		temp[i] = 1 / 4.0 - (i / 255.0 - 1 / 2.0) * (i / 255.0 - 1 / 2.0);
		count += temp[i];
	}
	printf("%f\n",count);
	for (int i = 0; i < 256; i++)
	{
		ptrHistagram[i] =int(w*temp[i] / count);
	}
	return ptrHistagram;
}

  • 获取规定化图像的累计直方图（如上2）

  • 用原图的累计概率匹配规定化的累计概率：

    即是，找出与原概率最接近的规定化的概率，便将其灰度值相匹配

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int* RegHistagram(double* ptrGAgram, double* ptrGAgram2)
{
	int* ptrRegram = new int[256];
	memset(ptrRegram, 0, sizeof(ptrRegram));
	for (int i = 0; i < 256; i++)
	{
		if (ptrGAgram[i] <= ptrGAgram2[0])
			ptrRegram[i] = 0;
		else
			for (int j = 1; j < 256; j++)
			{
				if (ptrGAgram[i] > ptrGAgram2[j] && ptrGAgram[i] <= ptrGAgram2[j + 1])
				{
					if ((ptrGAgram[i] - ptrGAgram2[j]) > (ptrGAgram2[j + 1] - ptrGAgram[i]))
						ptrRegram[i] = j;
					else
						ptrRegram[i] = j + 1;
				}
			}
	}
	return ptrRegram;
}