【学习OpenCV】图像的亮度/对比度调整
原理在这里有所阐述：
http://www.jizhuomi.com/software/257.html
http://blog.csdn.net/pizi0475/article/details/6740428
自己写个小界面测试一下
VS2012 MFC，OpenCV 3.0beta
添加以下控件：
1、一个button，IDC_BUTTON1，用于打开图片；
2、2个slider，IDC_CONTRAST和IDC_BRIGHTNESS，用于调对比度和亮度，分别添加控件变量m_slider1和m_slider2；
3、2个edit，IDC_EDIT_CONTRAST和IDC_EDIT_BRIGHTNESS，用于显示对比度和亮度的调整值
编码：
1、**Dlg.h：
添加私有变量
int mValueContrast;
int mValueBrightness;
Mat img,img1;
添加头文件
#include "opencv2/contrib/contrib.hpp"
#include "opencv2/highgui/highgui.hpp"
2、往**Dlg类添加消息
WM_HScroll
添加消息处理函数
OnHScroll
编辑该函数
void CsetContrastAndBrightnessDlg::OnHScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar)
{
// TODO: 在此添加消息处理程序代码和/或调用默认值
CSliderCtrl *pSlidCtrl=(CSliderCtrl*)GetDlgItem(IDC_CONTRAST);
mValueContrast=pSlidCtrl->GetPos();//取得当前位置值
pSlidCtrl=(CSliderCtrl*)GetDlgItem(IDC_BRIGHTNESS);
mValueBrightness=pSlidCtrl->GetPos();//取得当前位置值
UpdateData(FALSE); //刷新edit控件
//刷新显示
setContrastBrightness(mValueBrightness,mValueContrast,img,img1);
imshow("im1",img1);
CDialogEx::OnHScroll(nSBCode, nPos, pScrollBar);
}
3、编写亮度对比度算法
void setContrastBrightness(double percentB, double percentC, Mat& img, Mat& result)
{
const double pi = 3.1415926535898;
//百分比转为调整系数，0~100 转为 -range~range，最大为[-1,1]
const double Crange = 0.7; //range越小，对比度调节的精度越高
double C = (percentC-50)* Crange/50; //取值范围:[-range,range]
const double Brange = 0.5;
double B = (percentB-50)* Brange/50;
double k = tan( (45 + 44 * C) / 180 * pi );
int channel=0;
int MAXGRAYVALUE=0;
int orgtype = img.type();
switch(orgtype)
{
case CV_8UC1:
channel = 1;
MAXGRAYVALUE =255;
break;
case CV_8UC3:
channel = 3;
MAXGRAYVALUE =255;
break;
case CV_16UC1:
channel = 1;
MAXGRAYVALUE =65535;
break;
default:
MAXGRAYVALUE =65535;break;
}
double threshold = MAXGRAYVALUE/2;
vector<Mat> mv(channel);
Mat imgcyp;
img.convertTo(imgcyp,CV_32F);
split(imgcyp,mv);
for(int i=0;i<channel;i++)
{
mv[i] = (mv[i] - threshold * (1 - B)) * k + threshold * (1 + B);
}
merge(mv,result);
result.convertTo(result,orgtype);
}4、为botton添加事件响应函数
OnBnClickedButton1
编辑该函数
void CsetContrastAndBrightnessDlg::OnBnClickedButton1()
{
//选择文件
CFileDialog* dlg = new CFileDialog(TRUE,"(*.*)|*.*",NULL,4|2,"图像文件(*.*)|*.*||"); //新建CFileDialog对象
dlg->m_ofn.lpstrInitialDir="I:\\素材"; //指定初始目录
CString mPath;
CString mFileName;
if (IDOK==dlg->DoModal())
{
mPath = dlg->GetPathName(); //获取路径
mFileName = dlg->m_ofn.lpstrFileTitle;
}
delete dlg;
img = imread(mPath.GetBuffer(0));
namedWindow("im1", CV_WINDOW_AUTOSIZE);
imshow("im1",img);
}5、改写OnInitDialog()函数，添加以下代码
// TODO: 在此添加消息处理程序代码和/或调用默认值
m_slider1.SetRange(0,100);//设置滑动范围
m_slider1.SetTicFreq(1);//每10个单位画一刻度
m_slider1.SetPos(50);
m_slider2.SetRange(0,100);//设置滑动范围
m_slider2.SetTicFreq(1);//每10个单位画一刻度
m_slider2.SetPos(50);
mValueContrast = 50;
mValueBrightness=50;//取得当前位置值
UpdateData(FALSE); //刷新edit控件6、改写DoDataExchange()函数，添加以下代码
DDX_Text(pDX, IDC_EDIT_CONTRAST, mValueContrast); DDX_Text(pDX, IDC_EDIT_BRIGHTNESS, mValueBrightness);