How to Use a Simple to Filter the Skin Color?
How to use a simple to filter the skin color?¶
Introduction
The skin filter can filter to skin color. There is a simple rule to filter the skin color. We operate in YUV color space and find out skin pixels.
Equipment
Operation System: Microsoft Windows 7 (64 bit)
Development Utility: Microsoft Visual Studio 2010
Usage
// The height of the image.
for ( int iY = 0; iY < image->DibInfo->bmiHeader.biHeight; iY++ )
{
// The width of the image.
for ( int iX = 0; iX < image->DibInfo->bmiHeader.biWidth; iX++ )
{
// The index of the image. We use 24 bits of depth. So we need to be multiplied by three.
lIDX = ( iX * 3 ) + ( iY * image->DibInfo->bmiHeader.biWidth * 3 );
// Get the pixel of the red channel.
byteRGB_R = image->DibArry[lIDX+2];
// Get the pixel of the green channel.
byteRGB_G = image->DibArry[lIDX+1];
// Get the pixel of the blue channel.
byteRGB_B = image->DibArry[lIDX+0];
// Transform an RGB color space to YUV color space.
dYUV_Y = 0.257 * byteRGB_R + 0.504 * byteRGB_G + 0.098 * byteRGB_B + 16;
dYUV_U = -0.148 * byteRGB_R - 0.291 * byteRGB_G + 0.439 * byteRGB_B + 128;
dYUV_V = 0.439 * byteRGB_R - 0.368 * byteRGB_G - 0.071 * byteRGB_B + 128;
// This is skin thresholds.
if ( dYUV_U > 77.0f && dYUV_U < 127.0f &&
dYUV_V > 133.0f && dYUV_V < 173.0f )
{
// Set the pixel of the red channel.
image->DibArry[lIDX+2] = byteRGB_R;
// Set the pixel of the green channel.
image->DibArry[lIDX+1] = byteRGB_G;
// Set the pixel of the blue channel.
image->DibArry[lIDX+0] = byteRGB_B;
}
// Otherwise
else
{
// Set the pixels to black.
image->DibArry[lIDX+2] = 0;
image->DibArry[lIDX+1] = 0;
image->DibArry[lIDX+0] = 0;
}
} // The closing "The width of the image".
} // The closing "The height of the image".
You can download source code and binary code.
https://drive.google.com/file/d/0BzHb_OyLyVZlaTZGZnZnS1o2NEk/view?usp=sharing
Exception
There is a notice, if your bit depth of bitmap file are not 24 bits, you should change your bitmap files to adapt this program, or you could rewrite this source code to fit your bitmap format.
You have to install Microsoft SDK v7.1, because I include windowscodes.lib.
#pragma comment(lib, "windowscodecs.lib")
Reference
[1] Gary Bradski and Adrian Kaehler, “Learning OpenCV: Computer Vision with the OpenCV Library,” O’REILLY, September 2008, ISBN:978-0-596-51613-0
[2] Caltech Dataset, “Cars, Motorcycles, Airplanes, Faces, Leaves, Backgrounds,” http://www.vision.caltech.edu/html-files/archive.html
Acknowledge
Thank you (Microsoft Visual Studio 2010, Caltech) very much for this great development utility and provided the dataset.
