Use variable step size in stroke width ray construction.

TextDetection.cpp

@@ -387,7 +387,7 @@ void strokeWidthTransform (IplImage * edgeImage,
  IplImage * SWTImage,
  std::vector<Ray> & rays) {
  // First pass
- float prec = .05;
+ float eps = 0.0001;
  for( int row = 0; row < edgeImage->height; row++ ){
  const uchar* ptr = (const uchar*)(edgeImage->imageData + row * edgeImage->widthStep);
  for ( int col = 0; col < edgeImage->width; col++ ){
@@ -407,6 +407,7 @@ void strokeWidthTransform (IplImage * edgeImage,
  int curPixY = row;
  float G_x = CV_IMAGE_ELEM ( gradientX, float, row, col);
  float G_y = CV_IMAGE_ELEM ( gradientY, float, row, col);
+ float xdist,ydist,incr;
  // normalize gradient
  float mag = sqrt( (G_x * G_x) + (G_y * G_y) );
  if (dark_on_light){
@@ -417,9 +418,26 @@ void strokeWidthTransform (IplImage * edgeImage,
  G_y = G_y/mag;
 
  }
+ //std::cout << G_x << " " << G_y << std::endl;
  while (true) {
- curX += G_x*prec;
- curY += G_y*prec;
+ // populate curX and curY
+ if (G_x < 0) {
+ xdist = curX - floor(curX);
+ } else {
+ xdist = ceil(curX) - curX;
+ }
+ if (G_y < 0) {
+ ydist = curY - floor(curY);
+ } else {
+ ydist = ceil(curY) - curY;
+ }
+ incr = std::min(std::abs(ydist/G_y),std::abs(xdist/G_x))+eps;
+ //std::cout << std::abs(ydist/G_y) << ' ' << std::abs(xdist/G_x) << std::endl; 
+ //std::cout << curX << ' ' << curY << std::endl;
+ //std::cout << incr << std::endl;
+ //std::cout.flush();
+ curX += G_x*incr;
+ curY += G_y*incr;
  if ((int)(floor(curX)) != curPixX || (int)(floor(curY)) != curPixY) {
  curPixX = (int)(floor(curX));
  curPixY = (int)(floor(curY));