Morphological mission

Question

I use OpenCV for my image processing algorithms and try to fix the ragged edges in characters. I read that the hit-miss morphological transformation is a very good solution for this. Is there any open source implementation?

Or is there any other algorithm that can be used to fix dangling edges?

Answer 1

A simple hit and miss implementation can be found here :

#include <opencv2/imgproc/imgproc.hpp> // Hit-or-miss transform function void hitmiss(cv::Mat& src, // Source image, 8 bit single-channel matrix cv::Mat& dst, // Destination image cv::Mat& kernel) // Kernel. 1=foreground, -1=background, 0=don't care { CV_Assert(src.type() == CV_8U && src.channels() == 1); cv::Mat k1 = (kernel == 1) / 255; cv::Mat k2 = (kernel == -1) / 255; cv::normalize(src, src, 0, 1, cv::NORM_MINMAX); cv::Mat e1, e2; cv::erode(src, e1, k1); cv::erode(1 - src, e2, k2); dst = e1 & e2; } 

But I think that you can solve the problem only with the extension, as an example in page 7 of this slide (this is taken from "Digital Image Processing" from Gonzales and others)

Answer 2

Combined morphological dilatation and erosion using Marvin led to the following result:

Source:

 package characterRestoration; import marvin.image.MarvinColorModelConverter; import marvin.image.MarvinImage; import marvin.io.MarvinImageIO; import marvin.plugin.MarvinImagePlugin; import marvin.util.MarvinPluginLoader; public class CharacterRestoration { MarvinImage image = MarvinImageIO.loadImage("./res/character_in.png"); private MarvinImagePlugin dilation = MarvinPluginLoader.loadImagePlugin("org.marvinproject.image.morphological.dilation"); private MarvinImagePlugin erosion = MarvinPluginLoader.loadImagePlugin("org.marvinproject.image.morphological.erosion"); private boolean[][] matrixD = new boolean[][]{ {false,false,false,false,false,false,false,false,false}, {false,false,false,false,false,false,false,false,false}, {false,false,false,false,false,false,false,false,false}, {false,false,true,true,true,true,true,true,true}, {false,false,true,true,true,true,true,true,true}, {false,false,true,true,true,true,true,true,true}, {false,false,false,false,false,false,false,false,false}, {false,false,false,false,false,false,false,false,false}, }; private boolean[][] matrixE = new boolean[][]{ {true,true,true}, {true,true,true}, {true,true,true} }; public CharacterRestoration(){ // Convert image to binary format image = MarvinColorModelConverter.rgbToBinary(image, 125); // Morphological Dilation dilation.setAttribute("matrix", matrixD); dilation.process(image.clone(), image); // Morphological Erosion erosion.setAttribute("matrix", matrixE); erosion.process(image.clone(), image); MarvinImageIO.saveImage(image, "./res/character_out.png"); } public static void main(String[] args) { new CharacterRestoration(); } 

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