OpenCV-saturate_cast

OpenCV学习--saturate_cast防止数据溢出

在OpenCV学习中经常看见saturate_cast的使用，下面的代码会展示它的作用，详细的代码可以参见文章http://blog.csdn.net/mjlsuccess/article/details/12400787

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//使用图像混合例子中的C语言版本演示

for (int i=0; i<src1.rows; i++)

{

const uchar* src1_ptr = src1.ptr<uchar>(i);

const uchar* src2_ptr = src2.ptr<uchar>(i);

uchar* dst_ptr = dst.ptr<uchar>(i);

for (int j=0; j<src1.cols*nChannels; j++)

{

dst_ptr[j] = saturate_cast<uchar>(src1_ptr[j]*alpha + src2_ptr[j]*beta + gama);//gama = -100, alpha = beta = 0.5

// dst_ptr[j] = (src1_ptr[j]*alpha + src2_ptr[j]*beta + gama);

}

}

imshow("output2",dst);

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这里加入了溢出保护，结果如下



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//没加入溢出保护

for (int i=0; i<src1.rows; i++)

{

const uchar* src1_ptr = src1.ptr<uchar>(i);

const uchar* src2_ptr = src2.ptr<uchar>(i);

uchar* dst_ptr = dst.ptr<uchar>(i);

for (int j=0; j<src1.cols*nChannels; j++)

{

// dst_ptr[j] = saturate_cast<uchar>(src1_ptr[j]*alpha + src2_ptr[j]*beta + gama);//gama = -100, alpha = beta = 0.5

dst_ptr[j] = (src1_ptr[j]*alpha + src2_ptr[j]*beta + gama);

}

}

imshow("output2",dst);



大致的原理应该如下

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if(data<0)

data=0;

else if(data>255)

data=255;