[实现][选中][彩色]如何用bcb实现将选中的彩色jpg图片转成灰阶并在TImage中将灰阶图片显示出来。

作者:

3 Aug

我现在已经实现了将选中的彩色jpg图片在TImage中显示，请问如何将选中的彩色jpg图片转换成灰阶图片并在TImage中显示？急盼各位高手的回复！先谢了！

以上是Bitmap格式，你可先将JPG转成Bitmap再调用函数

C/C++ code

//—————————————————————————

#include <vcl.h>
#pragma hdrstop

#include "Unit1.h"
#include <jpeg.hpp>
//—————————————————————————
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//—————————————————————————
__fastcall TForm1::TForm1(TComponent* Owner)
    : TForm(Owner)
{
    Graphics::TBitmap *bmp = new Graphics::TBitmap();
    TJPEGImage *jpg = new TJPEGImage();
    try
    {
        jpg->LoadFromFile("D:\\VclLib\\GdiplusDemo\\Media\\100_0349.jpg");
        bmp->Assign(jpg);
        bmp->PixelFormat = pf24bit;
        BYTE *p = (BYTE*)bmp->ScanLine[bmp->Height - 1];
        int off = (((24 * bmp->Width + 31) & 0xffffffe0) >> 3) - bmp->Width * 3;
        for (int y = 0; y < bmp->Height; y ++, p += off)
        {
            for (int x = 0; x < bmp->Width; x ++)
            {
                int v = (117 * p[0] + 601 * p[1] + 306 * p[2] + 512) >> 10;
                *p ++ = v;
                *p ++ = v;
                *p ++ = v;
            }
        }
//        bmp->SaveToFile("d:\\tmp.bmp");
        Image1->Picture->Assign(bmp);
    }
    __finally
    {
        delete jpg;
        delete bmp;
    }
}
//—————————————————————————

C/C++ code

private:    // User declarations
        void   __fastcall   GrayIt(Graphics::TBitmap *bmp);
//—————————————————————————
void __fastcall TForm1::GrayIt(Graphics::TBitmap * bmp)
{
          BYTE * ptr;
          int Gray;
          bmp->PixelFormat=pf24bit;
          for(int y = 0; y<bmp->Height;y++)
          {
                  ptr=(BYTE*)bmp->ScanLine[y];
                  for(int x=0;x<bmp->Width*3;x+=3)
                  {
                        Gray=299*ptr[x+2]+587*ptr[x+1]+114*ptr[x];
                        ptr[x]=Gray/1000;
                        ptr[x+1]=Gray/1000;
                        ptr[x+2]=Gray/1000;

                  }
         }
}
//—————————————————————————
void __fastcall TForm1::Button1Click(TObject *Sender)
{
          Graphics::TBitmap *bmp=new Graphics::TBitmap;
          bmp->Assign(Image1->Picture->Graphic);
          GrayIt(bmp);
          Image1->Picture->Assign(bmp);
          delete bmp;
}
//—————————————————————————

//—————————————————————————
#include <vcl.h>//试例原码
#pragma hdrstop

#include "Unit1.h"
#include "math.h"
#include <printers.hpp>
//—————————————————————————
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//—————————————————————————
__fastcall TForm1::TForm1(TComponent* Owner)
: TForm(Owner)
{
}
//—————————————————————————

void __fastcall TForm1::FormCreate(TObject *Sender)
{
Scale->ItemIndex = 0;
PixelFormat->ItemIndex = 0;
ColorSpace->ItemIndex = 0;
Performance->ItemIndex = 0;
OpenDialog1->Filter = GraphicFilter(__classid(TGraphic));
FileListBox1->Mask = GraphicFileMask(__classid(TGraphic));

}
//—————————————————————————

void __fastcall TForm1::FileListBox1Click(TObject *Sender)
{
Image1->Picture->LoadFromFile(FileListBox1->FileName);
SetJPEGOptions(this);
}
//—————————————————————————
void __fastcall TForm1::Exit1Click(TObject *Sender)
{
Close();
}
//—————————————————————————
void __fastcall TForm1::Open1Click(TObject *Sender)
{
if (OpenDialog1->Execute()){
Image1->Picture->LoadFromFile(OpenDialog1->FileName);
SetJPEGOptions(this);
}
}
//—————————————————————————

void __fastcall TForm1::SetJPEGOptions(TObject *Sender)
{
bool isJpg;
isJpg = (Image1->Picture->Graphic->ClassNameIs("TJPEGImage"));
TJPEGImage *Jpeg;
if (isJpg){
Jpeg=(TJPEGImage *)Image1->Picture->Graphic;
Jpeg->PixelFormat = TJPEGPixelFormat(PixelFormat->ItemIndex);//位
Jpeg->Scale = TJPEGScale(Scale->ItemIndex); //比例
Jpeg->Grayscale = bool(ColorSpace->ItemIndex); //色彩
Jpeg->Performance = TJPEGPerformance(Performance->ItemIndex); //速度
}
Scale->Enabled = isJpg;
PixelFormat->Enabled = isJpg;
ColorSpace->Enabled = isJpg;
Performance->Enabled = isJpg;
}

.h文件
//—————————————————————————
#ifndef Unit1H
#define Unit1H
//—————————————————————————
#include <Classes.hpp>
#include <Controls.hpp>
#include <StdCtrls.hpp>
#include <Forms.hpp>
#include <ExtCtrls.hpp>
#include <FileCtrl.hpp>
#include <Dialogs.hpp>
#include <Menus.hpp>
#include <jpeg.hpp>
//—————————————————————————
class TForm1 : public TForm
{
__published: // IDE-managed Components
TPanel *Panel3;
TDriveComboBox *DriveComboBox1;
TComboBox *Scale;
TComboBox *PixelFormat;
TComboBox *ColorSpace;
TComboBox *Performance;
TPanel *Panel1;
TDirectoryListBox *DirectoryListBox1;
TFileListBox *FileListBox1;
TScrollBox *ScrollBox1;
TImage *Image1;
TMainMenu *MainMenu1;
TMenuItem *File1;
TMenuItem *Open1;
TMenuItem *N2;
TMenuItem *Exit1;
TOpenDialog *OpenDialog1;
void __fastcall FormCreate(TObject *Sender);
void __fastcall FileListBox1Click(TObject *Sender);
void __fastcall Exit1Click(TObject *Sender);
void __fastcall Open1Click(TObject *Sender);
void __fastcall SetJPEGOptions(TObject *Sender);
private:
public: // User declarations
__fastcall TForm1(TComponent* Owner);
};
//—————————————————————————
extern PACKAGE TForm1 *Form1;
//—————————————————————————
#endif

我是个新手，第一次发帖子，没想到一天时间就有这么多热心的人提供帮助，我真是太感动了！
这些Code我先回去试试，稍后再告诉大家问题是否得到了解决。谢谢了！

其实，你也可以直接算出灰度，用三元色相加再除三，就是灰度值

下面是核心语句

void __fastcall TMainForm::BitBtn1Click(TObject *Sender)
{
Image->Picture->Bitmap->PixelFormat = pf4bit;
}

我用maozefa的算法实现了图片转成灰阶，但是算法我还是看不懂，能否可以请maozefa帮忙解释一下？谢谢！

RGB颜色转灰度的经典公式是:
nGray=0.299*R+0.587*G+0.114*B
因为同样的单色G=255和B=255其亮度其实并不一样,所以(R+G+B)/3的方法不太准确.
maozefa的算法效率比较高,公式是一样的.

正如楼上说的，我的算法0.299*R+0.587*G+0.114*B，不过扩大了1024倍，转换为整数处理，最后右移10也就是除以1024还原。

获益不浅，非常感谢！

同类: C++ Builder

类别

C++ Builder

我爱builder

[实现][选中][彩色]如何用bcb实现将选中的彩色jpg图片转成灰阶并在TImage中将灰阶图片显示出来。

类别

最新

标签

链接

存档