Scene Character Reconstruction through Medial Axis
Shangxuan Tian, Palaiahnakote Shivakumara, Trung Quy Phan, Chew Lim Tan · 2013
Character shape reconstruction for the scene character is challenging and interesting because scene character usually suffers from uneven illumination, complex background, perspective distortion. To address such ill conditions, we propose to utilize Histogram Gradient Division (HGD) and Reverse Gradient Orientation (RGO) to select Candidate Text Pixels (CTPs) for a given input character. Ring Radius Transform is applied on each pixel in a CTP image to obtain radius map where each pixel is assigned a value which is the radius to the nearest CTP. Candidate medial axis pixels are those having maximum radius values in their neighborhoods. We find such pixels on horizontal, vertical, principal diagonal and secondary diagonal directions to determine the respective medial axis pixels. The union of all medial axis pixels at each pixel location is considered as a candidate medial axis pixel of the character. Then color difference and k-means clustering are employed to eliminate false candidate medial axis. The potential medial axis values are used to reconstruct the shape of the character. The method is tested on 1025 characters of complex foreground and background from ICDAR 2003 dataset in terms of shape reconstruction and recognition rate. Experimental results demonstrate the effectiveness of our proposed method for complex foreground and background characters in terms of character recognition rate and reconstruction error.