How to detect the skin color of face from the sour

I need to color the skin of the face... How do i find the skin color?

now i get the skin color by RGB pixel value ... Still i am facing the problem i was matching the color coordinates to match the skin by certain color range... but still some area of the face not fall in my range of colors then it is not color that area..

other than the face area may fall that region, that area also colored...

Any idea about my issue...

Thanks in advance....

MY code:

    -(void)colorImageBySliderValue:(float)value WithImage:(UIImage*)needToModified
{

    CGContextRef ctx;

    CGImageRef imageRef = needToModified.CGImage;
    NSUInteger width = CGImageGetWidth(imageRef);
    NSUInteger height = CGImageGetHeight(imageRef);
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    unsigned char *rawData = malloc(self.sourceImage.image.size.height * self.sourceImage.image.size.width * 10);
    NSUInteger bytesPerPixel = 4;
    NSUInteger bytesPerRow = bytesPerPixel * self.sourceImage.image.size.width;
    NSUInteger bitsPerComponent = 8;
    CGContextRef context1 = CGBitmapContextCreate(rawData, self.sourceImage.image.size.width, self.sourceImage.image.size.height,
                                                  bitsPerComponent, bytesPerRow, colorSpace,
                                                  kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
    CGColorSpaceRelease(colorSpace);

    CGContextDrawImage(context1, CGRectMake(0, 0, self.sourceImage.image.size.width, self.sourceImage.image.size.height), imageRef);

    NSLog(@"%d::%d",width,height);


    for(int ii = 0 ; ii < 768 * 1024 ; ii+=4)
    {

        int  R = rawData[ii];
        int G = rawData[ii+1];
        int B = rawData[ii+2];

        //        NSLog(@"%d   %d   %d", R, G, B);
             if( ( (R>60)&&(R<237) ) || ((G>10)&&(G<120))||((B>4) && (B<120)))
//        if( ( (R>100)&&(R<186) ) || ((G>56)&&(G<130))||((B>30) && (B<120)))
//        if( ( (R>188)&&(R<228) ) || ((G>123)&&(G<163))||((B>85) && (B<125)))
            //        if( ( (R>95)&&(R<220) ) || ((G>40)&&(G<210))||((B>20) && (B<170)))
        {


            rawData[ii+1]=R;//13; 
            rawData[ii+2]=G;//43; 
            rawData[ii+3]=value;//63
            //            NSLog(@"entered");
        }
    }


    ctx = CGBitmapContextCreate(rawData,
                                CGImageGetWidth( imageRef ),
                                CGImageGetHeight( imageRef ),
                                8,
                                CGImageGetBytesPerRow( imageRef ),
                                CGImageGetColorSpace( imageRef ),
                                kCGImageAlphaPremultipliedLast ); 

    imageRef = CGBitmapContextCreateImage(ctx);
    UIImage* rawImage = [UIImage imageWithCGImage:imageRef]; 
    UIImageView *ty=[[UIImageView alloc]initWithFrame:CGRectMake(100, 200, 400, 400)];
    ty.image=rawImage;
    [self.view addSubview:ty];
    CGContextRelease(context1);
    CGContextRelease(ctx);  
    free(rawData);   
}

Regards,

Spynet

you can create the two images one is the original image and other one is the modified image pixels alone and fix that... and and overlay the images by adding the original image first and the modified pixel alone over the original....

  for (int index=0; index<length; index+=4) 
        {
            if (data2[index]==data1[index])
            {
                data1[index]=data2[index];
                data1[index+1]=data2[index+1];//aRed+value;//aRed;//13; 
                data1[index+2]=data2[index+2];//aGreen;//aGreen;//43; 
                data1[index+3]=data2[index+3];
            }