数字图像处理学习笔记(1.3)---位图的读写、几何变换、傅里叶变换、直方图均衡

图像的直方图均衡

#include"bmp.h"
#include<cmath>
#include<cstring>
#include<cstdio>
#include<iostream>

int* m_histArray;
void Bitmap::releasedHist()
{
	if (m_histArray != NULL)
		delete[] m_histArray;
}

//说明：灰度图像统计直方图，m_histArray中存放了当前图像的统计数据

int* Bitmap::computeHistGray()
{
	//只处理灰度图像
	if (bitCount != 8)
		return NULL;

	//循环变量
	int i, j;

	m_histArray = new int[256];
	//直方图数组清0
	for (i = 0; i<256; i++)
		m_histArray[i] = 0;

	//每行像素所占字节数
	int lineByte = (width_p*bitCount/ 8 + 3) / 4 * 4;
	//中间变量
	int temp;

	//统计灰度直方图
	for (i = 0; i<17; i++){
		for (j = 0; j<width_p; j++){
			temp = *(dataBuf + i*lineByte + j);
			m_histArray[temp]++;
		}
	}
	return m_histArray;
}


//说明：彩色图像亮度直方图，m_histArray中存放了当前图像的亮度统计数据
int* Bitmap::computeHistBrightness()
{
	m_histArray = new int[256];
	//彩色图像有效
	if (bitCount != 24)
		return NULL;

	//循环变量
	int i, j;

	//直方图数组清0
	for (i = 0; i<256; i++)
		m_histArray[i] = 0;

	//每行像素所占字节数
	int lineByte = (width_p*bitCount / 8 + 3) / 4 * 4;

	//中间变量
	int temp;

	//统计亮度直方图
	for (i = 0; i<height_p; i++){
		for (j = 0; j<width_p; j++){
			temp = 0.11**(dataBuf + i*lineByte + j * 3 + 0)
				+ 0.59**(dataBuf + i*lineByte + j * 3 + 1)
				+ 0.30**(dataBuf + i*lineByte + j * 3 + 2) + 0.5;
			m_histArray[temp]++;
		}
	}
	return m_histArray;
}



//说明：彩色图像红色通道直方图，对图像红色分量的统计
int* Bitmap::computeHistRed()
{
	m_histArray = new int[256];
	//彩色图像有效
	if (bitCount != 24)
		return NULL;

	//循环变量
	int i, j;

	//直方图数组清0
	for (i = 0; i<256; i++)
		m_histArray[i] = 0;

	//每行像素所占字节数
	int lineByte = (width_p*bitCount / 8 + 3) / 4 * 4;

	//中间变量
	int temp;

	//统计红色通道直方图
	for (i = 0; i<height_p; i++){
		for (j = 0; j<width_p; j++){
			temp = *(dataBuf + i*lineByte + j * 3 + 2);
			m_histArray[temp]++;
		}
	}
	return m_histArray;
}

//说明：彩色图像绿色通道直方图，对图像绿色分量的统计
int* Bitmap::computeHistGreen()
{
	m_histArray = new int[256];
	//彩色图像有效
	if (bitCount != 24)
		return NULL;

	//循环变量
	int i, j;

	//直方图数组清0
	for (i = 0; i<256; i++)
		m_histArray[i] = 0;

	//每行像素所占字节数
	int lineByte = (width_p*bitCount / 8 + 3) / 4 * 4;

	//中间变量
	int temp;

	//统计绿色通道直方图
	for (i = 0; i<height_p; i++){
		for (j = 0; j<width_p; j++){
			temp = *(dataBuf + i*lineByte + j * 3 + 1);
			m_histArray[temp]++;
		}
	}
	return m_histArray;
}

//说明：彩色图像蓝色通道直方图，对图像蓝色分量的统计
int* Bitmap::computeHistBlue()
{
	m_histArray = new int[256];
	//彩色图像有效
	if (bitCount != 24)
		return NULL;

	//循环变量
	int i, j;

	//直方图数组清0
	for (i = 0; i<256; i++)
		m_histArray[i] = 0;

	//每行像素所占字节数
	int lineByte = (width_p*bitCount / 8 + 3) / 4 * 4;

	//中间变量
	int temp;

	//统计蓝色通道直方图
	for (i = 0; i<height_p; i++){
		for (j = 0; j<width_p; j++){
			temp = *(dataBuf + i*lineByte + j * 3 + 0);
			m_histArray[temp]++;
		}
	}
	return m_histArray;
}

//说明：计算直方图均值，直方图的统计特征
float Bitmap::computeHistAverage()
{
	if (bitCount == 8)
		m_histArray = computeHistGray();
	else if (bitCount == 24)
		m_histArray = computeHistBrightness();
	else
		return 0;
	int sum = 0;
	for (int i = 0; i<256; i++)
		sum += i*m_histArray[i];
	float m_average = (float)sum / (width_p*height_p);
	delete[] m_histArray;
	return m_average;
}
//说明：计算直方图方差，直方图的统计特征
float Bitmap::computeDeviation()
{
	if (bitCount == 8)
		m_histArray = computeHistGray();
	else if (bitCount == 24)
		m_histArray = computeHistBrightness();
	else
		return 0;
	float m_average = computeHistAverage();
	double deviation = 0;
	for (int i = 0; i<256; i++)
		deviation += (i - m_average)*(i - m_average)*m_histArray[i];

	deviation /= (width_p*height_p);

	float m_deviation = sqrt(deviation);
	delete[] m_histArray;
	return deviation;
}

//说明：直方图均衡，该函数只对灰度图像有效
void Bitmap::histEqualization()
{
	// 只处理灰度
	if (bitCount != 8)
		return;


	//输出图像每行像素所占的字节数
	int lineByte = (width_p*bitCount / 8 + 3) / 4 * 4;
	unsigned char* dataBufOut = new unsigned char[lineByte*height_p];

	//循环变量
	int i, j;

	//映射表
	double map[256];

	//中间变量
	int sum, tmp;

	//统计灰度直方图
	m_histArray=computeHistGray();

	//计算映射表
	sum = 0;
	for (i = 0; i<256; i++){
		sum += m_histArray[i];
		map[i] = (double)sum * 255 / (width_p*height_p) + 0.5;
	}

	//输出数据赋值
	for (i = 0; i<height_p; i++)
	{
		for (j = 0; j<width_p; j++)
		{
			tmp = *(dataBuf + i*lineByte + j);
			*(dataBufOut + i*lineByte + j) = (int)map[tmp];
		}
	}
	delete[] dataBuf;
	dataBuf = dataBufOut;
}

测试：

#include"bmp.h"
#include<iostream>

using namespace std;

int main()
{
	char* fileName = "qianxun.bmp";
	Bitmap* bmp = new Bitmap();
	bmp->read(fileName);
	bmp->histEqualization(); bmp->releasedHist();
	bmp->write("fourier.bmp");
	delete bmp;
	return 1;
}