To turn caring into action, we need to see a problem, see a solution, and see the impact. But complexity blocks all three steps.

If we can really see a problem, which is the first step, we come to the second step: cutting through the complexity to find a solution.

Cutting through complexity to find a solution runs through four predictable stages: determine a goal, find the highest-leverage approach, discover the ideal technology for that approach, and in the meantime, make the smartest application of the technology that you already have — whether it's something sophisticated, like a drug, or something simpler, like a bednet.

The final step – after seeing the problem and finding an approach – is to measure the impact of your work and share your successes and failures so that others learn from your efforts.

But if you want to inspire people to participate, you have to show more than numbers; you have to convey the human impact of the work – so people can feel what saving a life means to the families affected.

这样转换后，灰度图的灰阶分布在0~255之间。如果想把一幅彩色图渲染成双色图，定义一个深颜色darker，一个浅颜色lighter,那么灰度图只是一个darker是黑色而lighter是白色的特例。本来分布在0~255的灰阶，这样应该分别分布在(lighter.r~darker.r),(lighter.g~darker.g),(lighter.b~darker.b)。

编写代码如下，使用白色和紫色。

void CDuotoneDlg::OnButton1() 
{
    Bitmap  img(L"c:\\test1.jpg");
    Graphics graphix(this->GetDC()->m_hDC);

    Color darker(0);
    Color lighter(8414370);

    const float gray_r = 0.299f;
    const float gray_g = 0.587f;
    const float gray_b = 0.114f;

    float offset_r = (float)darker.GetR() / 255;
    float offset_g = (float)darker.GetG() / 255;
    float offset_b = (float)darker.GetB() / 255;    

    float r = (float)(lighter.GetR() - darker.GetR()) / 255;
    float g = (float)(lighter.GetG() - darker.GetG()) / 255;
    float b = (float)(lighter.GetB() - darker.GetB()) / 255;

    ImageAttributes imgatt;
    ColorMatrix matrix =
        {
           gray_r*r, gray_r*g, gray_r*b, 0, 0,
           gray_g*r, gray_g*g, gray_g*b, 0, 0,
           gray_b*r, gray_b*g, gray_b*b, 0, 0,
           0, 0, 0, 1, 0, 
           offset_r, offset_g, offset_b, 0, 1
        };

    imgatt.SetColorMatrix(&matrix, ColorMatrixFlagsDefault, ColorAdjustTypeBitmap);

    int iWidth = img.GetWidth();
    int iHeight = img.GetHeight();

    graphix.DrawImage(
        &img,
        Rect(0, 0, iWidth, iHeight),  
        0.0f,                         
        0.0f,                         
        iWidth,                       
        iHeight,                      
        UnitPixel,
        &imgatt);

    graphix.ReleaseHDC(this->GetDC()->m_hDC);
}