IPhone : OpenCV iOS improve text quality

Output Image Code applied :

            original = [MAOpenCV cvMatGrayFromAdjustedUIImage:_sourceImage];
            cv::GaussianBlur(original, original, cvSize(11,11), 0);
            cv::adaptiveThreshold(original, original, 255, cv::ADAPTIVE_THRESH_MEAN_C, cv::THRESH_BINARY, 5, 2);

            _adjustedImage = [MAOpenCV UIImageFromCVMat:original];

            original.release();

You can see there is very non sharped text. can we fill those white patches inside the character?so that our text can visible properly to do OCR. I am following MAImagePicker project.