color replacement in image for iphone application

Question

Basically i want to implement color replacement feature for my paint application. Below are original and expected output

Original:

Answer 1

I know this answer will be useful to someone someday. try this out in your view viewdidLoad() override method for iOS. image in the code snippet below should be from your UIImageView seed also is fixed.you can make it dynamic based on user tap event.

 cv::Mat mask = cv::Mat::zeros(image.rows + 2, image.cols + 2, CV_8U);
 imageView.image = [self UIImageFromCVMat:image];
 cv::cvtColor(image, image, cv::COLOR_BGR2RGB);

  try {
    if(seed.x > 0 && seed.y > 0){
        cv::floodFill(image, mask, seed, cv::Scalar(50, 155, 20) ,0,        cv::Scalar(2,2, 2), cv::Scalar(2,2, 2), 8);
        cv::floodFill(image, mask, seed2, cv::Scalar(50, 155, 20) ,0, cv::Scalar(2,2, 2), cv::Scalar(2,2, 2), 8);
        cv::floodFill(image, mask, seed3, cv::Scalar(50, 155, 0) ,0, cv::Scalar(2,2, 2), cv::Scalar(2,2, 2), 8);

    }
} catch (Exception ex) {

}
cv::cvtColor(image, image, cv::COLOR_RGB2BGR);

self.imageView.contentMode = UIViewContentModeScaleAspectFill;
self.imageView.image = [self UIImageFromCVMat:image];

Answer 2

Finally i am able to achieve some desired output using below javacv code and same ported to opencv too.

this solution has 2 problems

1. don't have edge detection, i think using contours i can achieve it

2. replaced color has flat hue and sat which should set based on source pixel hue sat difference but not sure how to achieve that. may be instead of cvSet using cvAddS

   IplImage image = cvLoadImage("sample.png");
   CvSize cvSize = cvGetSize(image);
   
   
   IplImage hsvImage = cvCreateImage(cvSize, image.depth(),image.nChannels());
   
   IplImage hChannel = cvCreateImage(cvSize, image.depth(), 1); 
           IplImage  sChannel = cvCreateImage(cvSize, image.depth(), 1); 
           IplImage  vChannel = cvCreateImage(cvSize, image.depth(), 1);
   cvSplit(hsvImage, hChannel, sChannel, vChannel, null);
   
   
   IplImage cvInRange = cvCreateImage(cvSize, image.depth(), 1);
   CvScalar source=new CvScalar(72/2,0.07*255,66,0); //source color to replace
   CvScalar from=getScaler(source,false);
   CvScalar to=getScaler(source, true);
   
   cvInRangeS(hsvImage, from , to, cvInRange);
   
   IplImage dest = cvCreateImage(cvSize, image.depth(), image.nChannels());
   
   IplImage temp = cvCreateImage(cvSize, IPL_DEPTH_8U, 2);
   cvMerge(hChannel, sChannel, null, null, temp);
   
   cvSet(temp, new CvScalar(45,255,0,0), cvInRange);// destination hue and sat
   cvSplit(temp, hChannel, sChannel, null, null);
   cvMerge(hChannel, sChannel, vChannel, null, dest);
   cvCvtColor(dest, dest, CV_HSV2BGR);
   cvSaveImage("output.png", dest);
   

method to for calculating threshold

    CvScalar getScaler(CvScalar seed,boolean plus){
    if(plus){
        return CV_RGB(seed.red()+(seed.red()*thresold),seed.green()+(seed.green()*thresold),seed.blue()+(seed.blue()*thresold));
    }else{
        return CV_RGB(seed.red()-(seed.red()*thresold),seed.green()-(seed.green()*thresold),seed.blue()-(seed.blue()*thresold));
    }
        }