C++-如何得到具有相同背景的图片中的不同部分?

Question

我想获取图片中不同的部分,应该如何做到? 我用dc来进行处理,但是得到的图失真了,代码如下:

// test1.cpp : Defines the entry point for the application.
//

#include "stdafx.h"
#include "test1.h"
#include <WindowsX.h>
#include <wingdi.h>
#pragma comment(lib,"Msimg32.lib")
#define MAX_LOADSTRING 100

// Global Variables:
HINSTANCE hInst;                                // current instance
TCHAR szTitle[MAX_LOADSTRING];                  // The title bar text
TCHAR szWindowClass[MAX_LOADSTRING];            // the main window class name

// Forward declarations of functions included in this code module:
ATOM                MyRegisterClass(HINSTANCE hInstance);
BOOL                InitInstance(HINSTANCE, int);
LRESULT CALLBACK    WndProc(HWND, UINT, WPARAM, LPARAM);

int APIENTRY _tWinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPTSTR    lpCmdLine,
                     int       nCmdShow)
{
    UNREFERENCED_PARAMETER(hPrevInstance);
    UNREFERENCED_PARAMETER(lpCmdLine);

    // TODO: Place code here.
    MSG msg;
    HACCEL hAccelTable;

    // Initialize global strings
    LoadString(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
    LoadString(hInstance, IDC_TEST1, szWindowClass, MAX_LOADSTRING);
    MyRegisterClass(hInstance);

    // Perform application initialization:
    if (!InitInstance (hInstance, nCmdShow))
    {
        return FALSE;
    }

    hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_TEST1));

    // Main message loop:
    while (GetMessage(&msg, NULL, 0, 0))
    {
        if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
    }

    return (int) msg.wParam;
}

ATOM MyRegisterClass(HINSTANCE hInstance)
{
    WNDCLASSEX wcex;

    wcex.cbSize = sizeof(WNDCLASSEX);

    wcex.style          = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc    = WndProc;
    wcex.cbClsExtra     = 0;
    wcex.cbWndExtra     = 0;
    wcex.hInstance      = hInstance;
    wcex.hIcon          = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_TEST1));
    wcex.hCursor        = LoadCursor(NULL, IDC_ARROW);
    wcex.hbrBackground  = (HBRUSH)(COLOR_WINDOW+1);
    wcex.lpszMenuName   = NULL;//MAKEINTRESOURCE(IDC_TEST1);
    wcex.lpszClassName  = szWindowClass;
    wcex.hIconSm        = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));

    return RegisterClassEx(&wcex);
}

BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
   HWND hWnd;

   hInst = hInstance; // Store instance handle in our global variable

   hWnd = CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
      CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL);

   if (!hWnd)
   {
      return FALSE;
   }

   ShowWindow(hWnd, nCmdShow);
   UpdateWindow(hWnd);

   return TRUE;
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{

    switch (message)
    {
    case WM_PAINT:
        {   
            PAINTSTRUCT ps;
            HDC hdc = BeginPaint(hWnd, &ps);                
            RECT rcClient;
            GetClientRect(hWnd,&rcClient);
            // TODO: Add any drawing code here...

            HDC hdcBk = CreateCompatibleDC(hdc);
            HBITMAP hBmpBk = LoadBitmap(hInst,MAKEINTRESOURCE(IDB_BITMAP2));//bk.bmp
            SelectBitmap(hdcBk,hBmpBk);

            HDC hdcPic = CreateCompatibleDC(hdc);
            HBITMAP hBmpPic = LoadBitmap(hInst,MAKEINTRESOURCE(IDB_BITMAP1));//pic.bmp
            SelectBitmap(hdcPic,hBmpPic);

            BitBlt(hdcPic,0,0,646,368,hdcBk,0,0,SRCINVERT);
//          BitBlt(hdc,0,0,646,368,hdcPic,0,0,SRCAND);
            
//          BitBlt(hdc,0,0,646,368,hdcPic,0,0,SRCAND);
//          BitBlt(hdc,0,0,646,368,hdcBk,0,0,SRCCOPY);
            TransparentBlt(hdc,0,0,646,368,hdcPic,0,0,646,368,RGB(0,0,0));

            DeleteBitmap(hBmpBk);
            DeleteBitmap(hBmpPic);
            DeleteDC(hdcBk);
            DeleteDC(hdcPic);
            EndPaint(hWnd, &ps);
        }break;
    //case WM_ERASEBKGND:break;
    case WM_DESTROY:
        {
            PostQuitMessage(0);
        }
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
    }
    return 0;
}

Answer 1

这个问题算是基本解决了, 但是感觉效率上不高效, 我是直接比较两个图片的像素,然后生成两张可以做SRCAND和SRCPAINT的位图, 然后就和网上常见的贴透明位图是一样的了, 我把方法放在了博客上, 代码没有经过优化, 需要的可以看一下:
http://www.cnblogs.com/likebeta/archive/2012/08/30/2663938.html

Answer 2

有没有试验过，用XOR计算。即将一个图片绘制上，另一个图片使用异或绘制。相同的背景部分，就是黑色的。