MFC对话框绘制灰度直方图
一.程序运行结果
????该篇文章主要是在上一篇文章基础上进行的讲解,其中当打开一张BMP图像后,点击”直方图“-》”显示原图直方图“如下。
二.灰度直方图原理
????什么是灰度直方图?????灰度直方图(histogram)是灰度级的函数,描述的是图像中每种灰度级像素的个数,反映图像中每种灰度出现的频率。横坐标是灰度级,纵坐标是灰度级出现的频率。
?????对于连续图像,平滑地从中心的高灰度级变化到边缘的低灰度级。直方图定义为:
?????其中A(D)为阈值面积函数:为一幅连续图像中被具有灰度级D的所有轮廓线所包围的面积。对于离散函数,固定ΔD为1,则:H(D)=A(D)-A(D+1)?????色彩直方图是高维直方图的特例,它统计色彩的出现频率,即色彩概率分布信息。?????通常这需要一定的量化过程,将色彩分成若干互不重叠的种类。一般不直接在RGB色彩空间中统计,而是在将亮度分离出来后,对代表色彩部分的信息进行统计,如在HSI空间的HS子空间、YUV空间的UV子空间,以及其它反映人类视觉特点的彩色空间表示中进行。????其中直方图的计算方法如下:?????依据定义,若图像具有L(通常L=256,即8位灰度级)级灰度,则大小为MxN的灰度图像f(x,y)的灰度直方图hist[0…L-1]可用如下计算获得。?????1、初始化hist[k]=0;k=0,…,L-1?????2、统计hist[f(x,y)]++;x=0,…,M-1,y=0,…,N-1?????3、归一化hist[f(x,y)]/=MN?????那么说了这么多,直方图究竟有什么作用呢?????在使用轮廓线确定物体边界时,通过直方图更好的选择边界阈值,进行阈值化处理;对物体与背景有较强对比的景物的分割特别有用;简单物体的面积和综合光密度IOD可以通过图像的直方图求得。
三.程序实现
1.建立直方图对话框
????第一步:创建Dialog????将视图切换到ResourceView界面,选中Dialog右键鼠标新建一个Dialog,并新建一个名为IDD_DIALOG_ZFT,设置成下图对话框。
????右键添加属性如下:????对话框-原始直方图-IDD_DIALOG_ZFT????组框-RGB-IDC_STATIC_RGB?????图像-框架-IDC_STATIC_KJ-蚀刻(重点:有它才能添加直方图在此处,注意GetDlgItem()函数中是IDC而不是IDD对话框)????添加蚀刻线(图像蚀刻形成的直线)形如图中的3个矩形框,并添加静态文本:Red、Green、Blue、红、绿、蓝、像素、平均灰度、中值灰度、标准差;这些静态文本都是IDC_STATIC且为默认属性????添加红色4个值(Static)、绿色4个值、蓝色4个值,分别为:????IDC_STATIC_XS_RED(GREENBLUE)对应像素XS????IDC_STATIC_PJHD_RED(GREENBLUE)对应平均灰度PJHD????IDC_STATIC_ZZHD_RED(GREEDBLUE)对应中值灰度ZZHD????IDC_STATIC_BZC_RED(GREENBLUE)对应标准差BZC
????第二步:建立类向导MFCClassWizard????(1)在对话框资源模板空白区双击鼠标(Ctrl+W),创建一个新类,命名为CImageZFTDlg会自动生成它的.h和.cpp文件。在类向导中选中类名CImageZFTDlg,IDs为CImageZFTDlg,WM_INITDIALOG建立这个函数用于初始化。????(2)打开类向导,选择MemberVariables页面,添加如下变量,类型均为CString。????像素m_redXS、m_greenXS、m_blueXS????标准差m_redBZC、m_greeenBZC、m_blueBZC????平均灰度m_redPJHD、m_greenPJHD、m_bluePJHD????中值灰度m_redZZHD、m_greenZZHD、m_blueZZHD
????(3)在View.cpp中添加直方图的头文件#inlcude"ImageZFTDlg.h"?????第三步:设置菜单栏调用直方图对话框????(1)将视图切换到ResourceView界面,选中Menu,在IDR_MAINFRAM中添加菜单项“直方图”,菜单属性中选择“弹出”,在“直方图”中添加子菜单“显示原图直方图”。????(2)设置其属性为ID_ZFT_YT(显示直方图原图),同时建立类向导,选择ID_ZFT_YT(IDs),通过COMMAND建立显示直方图函数OnZftYt()。
????第四步:添加代码及计算4个值????在ImageProcessingView.cpp中添加如下代码,注释中有如何求平均灰度、中值灰度和标准差的消息算法过程。
[cpp]?viewplain?copy
//引用显示直方图头文件??
#include?"ImageZFTDlg.h"??
#include?"math.h"??
??
/全局变量在TestZFTDlg.cpp中引用?用extern/??
int?Red[256],Green[256],Blue[256];??
??
//??
/?添加直方图显示功能,并在直方图下方显示相关信息??
/?如平均灰度、中值灰度、标准差和像素总数??????????
/?ID_ZFT_YT:直方图原图显示????????????????????????
//??
void?CImageProcessingView::OnZftYt()???
{??
????if(numPicture==0)?{??
????????AfxMessageBox("载入图片后才能显示原图直方图!",MB_OK,0);??
????????return;??
????}??
????AfxMessageBox("显示原图直方图!",MB_OK,0);??
????CImageZFTDlg?dlg;??
??
????//打开临时的图片??
????FILE?fpo?=?fopen(BmpName,"rb");??
????fread(&bfh,sizeof(BITMAPFILEHEADER),1,fpo);??
????fread(&bih,sizeof(BITMAPINFOHEADER),1,fpo);??
??????
????int?i,j;??
????for(j=0;j<256;j++)?{?//定义数组并清零??
????????Red[j]=0;??
????????Green[j]=0;??
????????Blue[j]=0;??
????}??
??????
????//计算4个数据??
????unsigned?char?red,green,blue;??
????int?IntRed,IntGreen,IntBlue;??????????????????//强制转换??
????double?sumRedHD=0,sumGreenHD=0,sumBlueHD=0;???//记录像素总的灰度值和??
????for(i=0;?i ????{??
????????fread(&red,sizeof(char),1,fpo);??
????????IntRed=int(red);??
????????sumRedHD=sumRedHD+IntRed;??
????????if(?IntRed>=0?&&?IntRed<256?)?Red[IntRed]++;?//像素0-255之间??
??????????
????????fread(&green,sizeof(char),1,fpo);??
????????IntGreen=int(green);??
????????sumGreenHD=sumGreenHD+IntGreen;??
????????if(?IntGreen>=0?&&?IntGreen<256?)?Green[IntGreen]++;??
??????????
????????fread(&blue,sizeof(char),1,fpo);??
????????IntBlue=int(blue);??
????????sumBlueHD=sumBlueHD+IntBlue;??
????????if(?IntBlue>=0?&&?IntBlue<256?)?Blue[IntBlue]++;??
????}??
????fclose(fpo);??
??????
????//像素:int型转换为CString型???
????dlg.m_redXS.Format("%d",m_nImage);??
????dlg.m_greenXS.Format("%d",m_nImage);??
????dlg.m_blueXS.Format("%d",m_nImage);??
??????
????//平均灰度值:计算24位bmp图片的灰度值,我是记录RGB中的所有平均值?????
????float?pinRedHD,pinGreenHD,pinBlueHD;???
????pinRedHD=sumRedHD3/m_nImage;??
????pinGreenHD=sumGreenHD3/m_nImage;?????//平均灰度=总灰度/总像素??
????pinBlueHD=sumBlueHD3/m_nImage;??
??????
????dlg.m_redPJHD.Format("%.2f",pinRedHD);??
????dlg.m_greenPJHD.Format("%.2f",pinGreenHD);??
????dlg.m_bluePJHD.Format("%.2f",pinBlueHD);??
??????
????//??
????/?中值灰度:算法重点(黄凯大神提供)???????????????????????????????
????/?中值灰度:所有像素中的中位数,应该所有像素排序找到中间的灰度值??
????/?算法:num[256]记录各灰度出现次数,sum+=num[i],找到sum=总像素/2??
????//??
????int?sumRedZZHD=0,sumGreenZZHD=0,sumBlueZZHD=0;??
????int?redZZHD,greenZZHD,blueZZHD;??
????for(i=0;i<256;i++)??
????{??
????????sumRedZZHD=sumRedZZHD+Red[i];??
????????if(sumRedZZHD>=m_nImage/6)??????????//m_nImage被分成3份RGB并且sum=总像素/2??
????????{??
????????????redZZHD=i;??
????????????break;??
????????}??
????}??
????for(i=0;i<256;i++)??
????{??
????????sumGreenZZHD=sumGreenZZHD+Green[i];??
????????if(sumGreenZZHD>=m_nImage/6)??????????//m_nImage被分成3份RGB并且sum=总像素/2??
????????{??
????????????greenZZHD=i;??
????????????break;??
????????}??
????}??
????for(i=0;i<256;i++)??
????{??
????????sumBlueZZHD=sumBlueZZHD+Blue[i];??
????????if(sumBlueZZHD>=m_nImage/6)??????????//m_nImage被分成3份RGB并且sum=总像素/2??
????????{??
????????????blueZZHD=i;??
????????????break;??
????????}??
????}??
??????
????dlg.m_redZZHD.Format("%d",redZZHD);??
????dlg.m_greenZZHD.Format("%d",greenZZHD);??
????dlg.m_blueZZHD.Format("%d",blueZZHD);??
??????
????//??
????/标准差:标准差=方差的算术平方根????????????????????????????????????
????/???????方差s^2=[(x1-x)^2+(x2-x)^2+......(xn-x)^2]/n??????????????
????/?算法:不用开m_nImage数组进行计算?用num[256]中数进行??????????????
????/?方差=(平均灰度-i)(平均灰度-i)Red[i]??有Red[i]个灰度值为i的数??
????//??
????float?redBZC,greenBZC,blueBZC;???????//标准差??
????double?redFC=0,greenFC=0,blueFC=0;????//方差??
????for(i=0;i<256;i++)??
????{??
????????redFC=redFC+(pinRedHD-i)(pinRedHD-i)Red[i];???//有Red[i]个像素i??
????????greenFC=greenFC+(pinGreenHD-i)(pinGreenHD-i)Green[i];??
????????blueFC=blueFC+(pinBlueHD-i)(pinBlueHD-i)Blue[i];??
????}??
??????
????redBZC=sqrt(redFC3/m_nImage);??
????greenBZC=sqrt(greenFC3/m_nImage);??
????blueBZC=sqrt(blueFC3/m_nImage);??
??????
????dlg.m_redBZC.Format("%.2lf",redBZC);??
????dlg.m_greenBZC.Format("%.2lf",greenBZC);??
????dlg.m_blueBZC.Format("%.2lf",blueBZC);????
??
????//重点必须添加该语句才能弹出对话框??
????if(dlg.DoModal()==IDOK)??
????{??
??
????}??
}??
????第五步:此时运行结果如下图所示,打开图片可以显示参数。
2.建立对话框与View联系并绘制直方图
?????重点(极其重要)?????(1)如何在MFC中(View中)实现对子对话框的画图或直方图响应?????解决方法:在子对话框中.cpp文件中实现画图响应,不要再View.cpp中实现,否则图像会以menu背景为坐标,而在ImageZFTDlg.cpp中建立OnPaint函数实现画图,它默认会以子对话框为标准。?????(2)如何把View.cpp中的图片像素直方图信息传递给子对话框ImageZFTDlg.cpp呢?????解决方法:如果自定义ImageStruct.h中建立全局变量,每个.cpp中引用该头文件调用总是报错(未知),所以我在View.h中建立一个全局变量intRed[256];再在子文件.cpp中函数里调用该全局变量即可externintRed[256],这是非常重要的一个C语言知识。?????(3)画图函数OnPaint()参考源代码中详细注释。????如何绘制坐标轴、文字、图像,其实自己绘制而没调用第三方库还是挺有意思的。?????第一步:建立画直方图函数OnPaint????打开类向导(Ctrl+W),类名选择CImageZFTDlg,IDs选择CImageZFTDlg,在Message函数中建立WM_PAINT映射,默认函数名为OnPaint建立函数voidCImageZFTDlg::OnPaint()?????第二步:绘制直方图大致思想如下????(1)重点:获取要绘制直方图的位置和图像资源的对应号ID(IDC_STATIC_KJ框架),我当时认为绘制直方图只能绘制到”图像“控件IDC中,不能是对话框IDD。?????CWndpWnd=GetDlgItem(IDC_STATIC_KJ);????CDCpDC=pWnd->GetDC();????(2)获取对话框矩形的长和宽?????CRectrectpic;????GetDlgItem(IDC_STATIC_KJ)->GetWindowRect(&rectpic);????(3)创建画笔对象并对画笔进行颜色设置?????CPenRedPen=newCPen();????RedPen->CreatePen(PS_SOLID,1RGB(255,0,0));????(4)选中当前画笔并保存以前画笔?????CGdiObjectRedOlderPen=pDC->SelectObject(RedPen);????(5)绘制直方图(图像坐标自己算)?????矩形pDC->Rectangle(9,327,312,468);????移动pDC->MoveTo(15,331);????直线pDC->LineTo(15,488);????文字pDC->TextOut(15+48i,450,str);????(6)恢复以前画笔?????pDC->SelectObject(RedOlderPen);????deleteRedPen;????ReleaseDC(pDC);?????第三步:源代码与详细注释思想????在ImageZFTDlg.cpp中修改OnPaint函数:
[cpp]?viewplain?copy
//绘制原图直方图//??
void?CImageZFTDlg::OnPaint()???
{??
????CPaintDC?dc(this);?//?device?context?for?painting??
??????
????//?TODO:?Add?your?message?handler?code?here??
??????
????//??
????/?重点知识:(百度)???????????????????????????????????????????????????????????????
????/?如何在View.cpp中把一个变量的值传给其它对话框??????????????????????????????????
????/???????????????????????????????????????????????????????????????????????????????
????/?错误一:在View.h中定义的pubic变量只能在View.cpp中用????????????????????????????
????/?错误二:定义一个Struct.h中存全局变量,在2个函数中分别调用#include?"Struct.h"????
????/???????????????????????????????????????????????????????????????????????????????
????/?解决方法一:?(CSDN?不会)参数用?A&?a?两个对话框里都可以访问a????????????????????
????/?解决方法二:?(CSDN?不会)重载???????????????????????????????????????????????????
????/???????????????????????????????????????????????????????????????????????????????
????/?解决:在View.cpp中定义全局变量?void?CBmpDrawView::OnZftYt()?前面?并函数中操作??
????/??????在dialog的cpp中即void?CTestZFTDlg::OnPaint()中在定义一个extern?int?a?????
????//??
??
????extern?int?Red[256],Green[256],Blue[256];??
??
????/写在该空间中可以省略Invalidate()语句/??
????/获取控件的CDC指针/??
????CRect?rectpic;??
????GetDlgItem(IDC_STATIC_KJ)->GetWindowRect(&rectpic);??
??????????
????int?x,y;??
????x=rectpic.Width();??
????y=rectpic.Height();??
??????????
????CWnd?pWnd=GetDlgItem(IDC_STATIC_KJ);??
????CDC?pDC=pWnd->GetDC();??
??????????
????//??
????/重点:画直方图?红色?
????//??
????CPen?RedPen=new?CPen();??????????????????????????????//创建画笔对象??
????RedPen->CreatePen(PS_SOLID,1,RGB(255,0,0));???????????//红色画笔??
????CGdiObject?RedOlderPen=pDC->SelectObject(RedPen);????//选中当前红色画笔并保存以前的画笔??
??????
????/画图/??
????pDC->Rectangle(9,16,312,147);??????//画一个矩形框??
????pDC->MoveTo(15,20);????????????????//绘制坐标轴??
????pDC->LineTo(15,128);???????????????//Y竖轴??
????pDC->LineTo(305,128);??????????????//X横轴??
??????
????pDC->MoveTo(305,128);??????????????//绘制X箭头??
????pDC->LineTo(300,123);??????????????//绘制上边箭头??
????pDC->MoveTo(305,128);???
????pDC->LineTo(300,133);??????????????//绘制下边箭头??
??????
????pDC->MoveTo(15,20);????????????????//绘制Y箭头??
????pDC->LineTo(10,25);????????????????//绘制左边箭头??
????pDC->MoveTo(15,20);??
????pDC->LineTo(20,25);????????????????//绘制右边箭头??
??????
????//??
????/?TextOut函数功能:????????????????????????????????????????????????????
????/?该函数用当前选择的字体、背景颜色和正文颜色将一个字符串写到指定位置??
????/?BOOL?TextOut(HDC?hdc,int?x,int?y,LPCTSTR?str,int?numStr)????????????
????/?表示:x起始坐标,y起始坐标,字符串,字符串中字符个数????????????????????
????/?
????/?SetTextColor函数功能:???????????????????????????????????????????????
????/?设置指定设备环境(HDC)的字体颜色?????????????????????????????????????
????/?SetTextColor?(HDC,?COLORREF)?如:SetTextColor(HDC,RGB(255,0,0));?????
????//??
??????
????CString?str;??
????int?i;??
????for(i=0;i<=5;i++)????????????????????//写X轴刻度线??
????{??
????????str.Format("%d",i50);???????????????//0-255之间添加6个刻度值??
????????pDC->SetTextColor(RGB(255,0,255));???//设置字体颜色??
????????pDC->TextOut(15+48i,130,str);???????//输出字体??
????????pDC->MoveTo(15+48i,128);????????????//绘制X轴刻度??
????????pDC->LineTo(15+48i,125);??
????}??
????for(i=0;i<=5;i++)????????????????????????//写Y轴刻度线??
????{??
????????pDC->MoveTo(15,128-20i);????????????//绘制Y轴刻度??
????????pDC->LineTo(18,128-20i);??
????}??
??????
????/绘制直方图主要的代码/??
????for(i=1;i<256;i++)??
????{??
????????pDC->MoveTo(15+i,128);??
????????if(?(128-16)?>?(Red[i]/40)?)??
????????????pDC->LineTo(15+i,128-(Red[i]/40));?????
????????else??
????????????pDC->LineTo(15+i,16);????????????//超过矩形的画矩形高??
????}??
??????????
??
????//??
????/重点:画直方图?绿色?
????//??
????CPen?GreenPen=new?CPen();?????????????????????????????//创建画笔对象??
????GreenPen->CreatePen(PS_SOLID,1,RGB(0,255,0));??????????//绿色画笔??
????CGdiObject?GreenOlderPen=pDC->SelectObject(GreenPen);???
??????
????pDC->Rectangle(9,167,312,308);?????//画一个矩形框??
????pDC->MoveTo(15,171);???????????????//绘制坐标轴??
????pDC->LineTo(15,288);???????????????//Y竖轴??
????pDC->LineTo(305,288);??????????????//X横轴??
??????
????pDC->MoveTo(305,288);??????????????//绘制X箭头??
????pDC->LineTo(300,283);??????????????//绘制上边箭头??
????pDC->MoveTo(305,288);??
????pDC->LineTo(300,293);??????????????//绘制下边箭头??
??????
????pDC->MoveTo(15,171);????????????????//绘制Y箭头??
????pDC->LineTo(10,176);????????????????//绘制左边箭头??
????pDC->MoveTo(15,171);??
????pDC->LineTo(20,176);????????????????//绘制右边箭头??
??????
????for(i=0;i<=5;i++)???????????????????//写X轴刻度线??
????{??
????????str.Format("%d",i50);???????????????//0-255之间添加6个刻度值??
????????pDC->SetTextColor(RGB(255,0,255));???//设置字体颜色??
????????pDC->TextOut(15+48i,290,str);???????//输出字体??
??????????
????????pDC->MoveTo(15+48i,288);????????????//绘制X轴刻度??
????????pDC->LineTo(15+48i,285);??
????}??
????for(i=0;i<=5;i++)????????????????????????//写Y轴刻度线??
????{??
????????pDC->MoveTo(15,288-20i);????????????//绘制Y轴刻度??
????????pDC->LineTo(18,288-20i);??
????}??
??????
????/绘制直方图主要的代码/??
????for(i=1;i<256;i++)??
????{??
????????pDC->MoveTo(15+i,288);??
????????if(?(288-167)?>?(Green[i]/40)?)??
????????????pDC->LineTo(15+i,288-(Green[i]/40));?????
????????else??
????????????pDC->LineTo(15+i,167);????????????//超过矩形的画矩形高??
????}??
??????????
??????????
????//??
????/重点:画直方图?蓝色?
????/((/??
????CPen?BluePen=new?CPen();????????????????????????????//创建画笔对象??
????BluePen->CreatePen(PS_SOLID,1,RGB(0,0,255));?????????//蓝色画笔??
????CGdiObject?BlueOlderPen=pDC->SelectObject(BluePen);????
??????
????pDC->Rectangle(9,327,312,468);??????//画一个矩形框??
????pDC->MoveTo(15,331);????????????????//绘制坐标轴??
????pDC->LineTo(15,448);????????????????//Y竖轴??
????pDC->LineTo(305,448);???????????????//X横轴??
??????
????pDC->MoveTo(305,448);???????????????//绘制X箭头??
????pDC->LineTo(300,443);???????????????//绘制上边箭头??
????pDC->MoveTo(305,448);??
????pDC->LineTo(300,453);???????????????//绘制下边箭头??
??????
????pDC->MoveTo(15,331);????????????????//绘制Y箭头??
????pDC->LineTo(10,336);????????????????//绘制左边箭头??
????pDC->MoveTo(15,331);??
????pDC->LineTo(20,336);????????????????//绘制右边箭头??
??????
??????
????for(i=0;i<=5;i++)???????????????????//写X轴刻度线??
????{??
????????str.Format("%d",i50);???????????????//0-255之间添加6个刻度值??
????????pDC->SetTextColor(RGB(255,0,255));???//设置字体颜色??
????????pDC->TextOut(15+48i,450,str);???????//输出字体??
??????????
????????pDC->MoveTo(15+48i,448);????????????//绘制X轴刻度??
????????pDC->LineTo(15+48i,445);??
????}??
????for(i=0;i<=5;i++)????????????????????????//写Y轴刻度线??
????{??
????????pDC->MoveTo(15,448-20i);????????????//绘制Y轴刻度??
????????pDC->LineTo(18,448-20i);??
????}??
??????
????/绘制直方图主要的代码/??
????for(i=1;i<256;i++)??
????{??
????????pDC->MoveTo(15+i,448);??
????????if(?(448-327)?>?(Blue[i]/40)?)??
????????????pDC->LineTo(15+i,448-(Blue[i]/40));?????
????????else??
????????????pDC->LineTo(15+i,327);????????????//超过矩形的画矩形高??
????}??
??????????
??????????????
????//恢复以前的画笔??
????pDC->SelectObject(RedOlderPen);??
????pDC->SelectObject(GreenOlderPen);??
????pDC->SelectObject(BlueOlderPen);??
????delete?RedPen;??
????delete?GreenPen;??
????delete?BluePen;??
????ReleaseDC(pDC);??
????return;??
??????
????//?Do?not?call?CDialog::OnPaint()?for?painting?messages??
}??
????此时运行程序即可显示直方图。????最后还是希望文章对你有所帮助,如果文章有不足或错误之处,请海涵~文章不仅仅讲述了直方图相关的知识,同时文章也给你提供了一种绘制坐标图像的思想和详细注释。有时候一直怀疑回忆这些知识会让我停滞不前,但心安即好,何必在意!????从来没有什么终南捷径和大神,真正的捷径只有三个:坚持、专注、认真。其他的都是细枝末节,做到这三个,其他的自然而然都会拥有。——同学CY
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