Kristou Says » C++

Color interpolation in OpenCV

Kristou Mehrez — Wed, 23 Dec 2009 04:23:07 +0000

I could not find in Internet a function which can return a RGB color value between two colors So I had to do it myself. I hope it will be useful for someone.

CvScalar interpolate(CvScalar c1, CvScalar c2, double value){ if( value <= 0.0 ){ return c1; } if( value >= 1.0 ){ return c2; } int red = cvRound((1.0 - value) * c1.val[2] + value * c2.val[2]); int green = cvRound((1.0 - value) * c1.val[1] + value * c2.val[1]); int blue = cvRound((1.0 - value) * c1.val[0] + value * c2.val[0]); return CV_RGB(red, green, blue); }

Remove items from deque, list or vector in a loop

Kristou Mehrez — Fri, 27 Nov 2009 15:42:53 +0000

Recently I needed to delete items from a sequence like a deque , list or vector from a for loop, I figured out that I have to do something like this:

for(iter = list.begin(); iter != list.end(); ++iter)
{
// your code
iter = list.erase(iter);
--iter;
// your code
}

It looks basic but it took me a while to figure it out so I wanted to share in case somebody need it.

C++: Convert int to string

Kristou Mehrez — Fri, 24 Jul 2009 12:19:21 +0000

This is an elegant function to convert int to string to use anywhere:

std::string intToString(int i)
{
    std::stringstream ss;
    std::string s;
    ss < < i;
    s = ss.str();

    return s;
}

C++: Delete or remove a file

Kristou Mehrez — Mon, 15 Jun 2009 13:19:03 +0000

To delete or remove a file in C++ you can use the remove function from stdio.h like follows:


#include 

int main(){ if(remove("myfile.txt") == -1)

    fprintf(stderr,"Remove failed");

// your code .......

}

OpenCV: Implementation of Eigenface

Kristou Mehrez — Wed, 10 Jun 2009 13:04:23 +0000

I found a good tutorial which explain how the face recognition method called eigenface works: Cognotics
This tutorial uses the deprecated function cvCalcEigenObjects().
The advised function is cvCalcPCA().