MFC 怎么把jpg图转换成单色位图 并保存成图片代码实现

以下是将jpg图转换成单色位图并保存成图片的MFC代码实现：

1. 加载jpg图并创建位图对象

CImage img;
img.Load(_T("example.jpg")); // 加载jpg图
CBitmap bmp;
bmp.Attach(img.Detach()); // 创建位图对象

2. 获取位图信息和像素数据

BITMAP bmpInfo;
bmp.GetBitmap(&bmpInfo); // 获取位图信息

int width = bmpInfo.bmWidth;
int height = bmpInfo.bmHeight;

BYTE* pPixels = new BYTE[bmpInfo.bmHeight * bmpInfo.bmWidthBytes];
bmp.GetBitmapBits(bmpInfo.bmHeight * bmpInfo.bmWidthBytes, pPixels); // 获取像素数据

3. 将像素数据转换成单色位图数据

BYTE* pMonoPixels = new BYTE[bmpInfo.bmHeight * bmpInfo.bmWidthBytes];
for (int row = 0; row < height; row++)
{
    for (int col = 0; col < width; col++)
    {
        BYTE* pPixel = &pPixels[row * bmpInfo.bmWidthBytes + col * 3];
        BYTE r = pPixel[0];
        BYTE g = pPixel[1];
        BYTE b = pPixel[2];

        // 灰度值计算公式
        BYTE gray = (BYTE)(0.299 * r + 0.587 * g + 0.114 * b);

        // 将灰度值转换为单色位图数据
        if (gray >= 128)
            pMonoPixels[row * bmpInfo.bmWidthBytes + col / 8] |= (0x80 >> (col % 8));
    }
}

4. 创建单色位图对象并设置位图数据

BITMAPINFOHEADER bih;
bih.biSize = sizeof(BITMAPINFOHEADER);
bih.biWidth = width;
bih.biHeight = height;
bih.biPlanes = 1;
bih.biBitCount = 1;
bih.biCompression = BI_RGB;
bih.biSizeImage = 0;
bih.biXPelsPerMeter = 0;
bih.biYPelsPerMeter = 0;
bih.biClrUsed = 0;
bih.biClrImportant = 0;

BITMAPINFO bmi;
bmi.bmiHeader = bih;

CBitmap monoBmp;
monoBmp.CreateBitmap(width, height, 1, 1, pMonoPixels);

delete[] pPixels;
delete[] pMonoPixels;

5. 保存单色位图为bmp文件

CImage monoImg;
monoImg.Attach(monoBmp);
monoImg.Save(_T("example_mono.bmp"), Gdiplus::ImageFormatBMP);

完整代码：

CImage img;
img.Load(_T("example.jpg")); // 加载jpg图
CBitmap bmp;
bmp.Attach(img.Detach()); // 创建位图对象

BITMAP bmpInfo;
bmp.GetBitmap(&bmpInfo); // 获取位图信息

int width = bmpInfo.bmWidth;
int height = bmpInfo.bmHeight;

BYTE* pPixels = new BYTE[bmpInfo.bmHeight * bmpInfo.bmWidthBytes];
bmp.GetBitmapBits(bmpInfo.bmHeight * bmpInfo.bmWidthBytes, pPixels); // 获取像素数据

BYTE* pMonoPixels = new BYTE[bmpInfo.bmHeight * bmpInfo.bmWidthBytes];
for (int row = 0; row < height; row++)
{
    for (int col = 0; col < width; col++)
    {
        BYTE* pPixel = &pPixels[row * bmpInfo.bmWidthBytes + col * 3];
        BYTE r = pPixel[0];
        BYTE g = pPixel[1];
        BYTE b = pPixel[2];

        // 灰度值计算公式
        BYTE gray = (BYTE)(0.299 * r + 0.587 * g + 0.114 * b);

        // 将灰度值转换为单色位图数据
        if (gray >= 128)
            pMonoPixels[row * bmpInfo.bmWidthBytes + col / 8] |= (0x80 >> (col % 8));
    }
}

BITMAPINFOHEADER bih;
bih.biSize = sizeof(BITMAPINFOHEADER);
bih.biWidth = width;
bih.biHeight = height;
bih.biPlanes = 1;
bih.biBitCount = 1;
bih.biCompression = BI_RGB;
bih.biSizeImage = 0;
bih.biXPelsPerMeter = 0;
bih.biYPelsPerMeter = 0;
bih.biClrUsed = 0;
bih.biClrImportant = 0;

BITMAPINFO bmi;
bmi.bmiHeader = bih;

CBitmap monoBmp;
monoBmp.CreateBitmap(width, height, 1, 1, pMonoPixels);

delete[] pPixels;
delete[] pMonoPixels;

CImage monoImg;
monoImg.Attach(monoBmp);
monoImg.Save(_T("example_mono.bmp"), Gdiplus::ImageFormatBMP);