Golang : Eroding and dilating image with OpenCV example



Tags : golang opencv erode dilate morphology

I'm learning OpenCV by going through some of the examples found on OpenCV website. For this post, below is an example of Erode and Dilate implementations in Golang.

In a nutshell, Erosion and Dilation are two basic morphological operations that can help in

  • Removing noise from input image
  • Isolation of individual elements and joining disparate elements in an image.
  • Finding of intensity bumps or holes in an image

Also, erosion and dilation can help in reducing the amount of data to be processed, thus speeding up the algorithms that depend on the output images.

For more detailed information, please see the OpenCV tutorial at http://docs.opencv.org/2.4.2/doc/tutorials/imgproc/erosiondilatation/erosiondilatation.html.

An screenshot example of Erode and Dilate operations written in Golang:

screenshot example of Erode and Dilate operations

You can use this image

image of letter J

(http://docs.opencv.org/2.4.2/images/Morphology1TutorialTheoryOriginalImage.png) for running test with the program below.

Here you go!


 package main

 import (
 "fmt"
 "github.com/lazywei/go-opencv/opencv"
 "os"
 )

 var (
 originalWindow = new(opencv.Window)
 processedImageWindow = new(opencv.Window)
 image = new(opencv.IplImage)
 processedImage = new(opencv.IplImage)
 element *opencv.IplConvKernel
 kernelSlider = 5
 erodeDilateSlider = 0
 kernelSize = 1
 )

 func process() {

 element = opencv.CreateStructuringElement(kernelSize, kernelSize, kernelSize/2, kernelSize/2, opencv.CV_MORPH_RECT)
 defer element.ReleaseElement()
 if erodeDilateSlider == 0 {
 fmt.Printf("Erode by %dx%d\n", kernelSize, kernelSize)
 opencv.Erode(image, processedImage, element, 1)
 } else {
 fmt.Printf("Dilate by %dx%d\n", kernelSize, kernelSize)
 opencv.Dilate(image, processedImage, element, 1)
 }
 processedImageWindow.ShowImage(processedImage)
 }

 func kernelTrackBar(position int, param ...interface{}) {
 kernelSize = position

 if kernelSize%2 == 0 {
 kernelSize = kernelSize + 1
 }
 processedImageWindow.SetTrackbarPos("Kernel Size : ", kernelSize)
 process()
 fmt.Printf("Kernel size  = %dx%d\n", kernelSize, kernelSize)
 }

 func erodeDilateTrackBar(position int, param ...interface{}) {
 process()
 erodeDilateSlider = position
 }

 func main() {

 if len(os.Args) != 2 {
 fmt.Printf("Usage : %s <image filename>\n", os.Args[0])
 os.Exit(0)
 }

 imageFileName := os.Args[1]

 fmt.Println("Loading image from ", imageFileName)
 fmt.Println("Press ESC key to quit")

 image = opencv.LoadImage(imageFileName)
 if image == nil {
 panic("LoadImage failed")
 }
 defer image.Release()

 originalWindow = opencv.NewWindow("Original Image")
 defer originalWindow.Destroy()

 processedImageWindow = opencv.NewWindow("Processed Image")
 processedImageWindow.Move(200, 300)
 defer processedImageWindow.Destroy()

 // init with 5x5 kernel size
 element = opencv.CreateStructuringElement(5, 5, erodeDilateSlider/2, erodeDilateSlider/2, opencv.CV_MORPH_RECT)
 defer element.ReleaseElement()

 processedImage = image.Clone()

 // 3rd parameter iteration = number of multiple erosions
 // we settle for 1
 opencv.Erode(image, processedImage, element, 1)

 processedImageWindow.CreateTrackbar("Kernel Size : ", 1, 21, kernelTrackBar)
 processedImageWindow.CreateTrackbar("Erode(0)/Dilate(1)  : ", 0, 1, erodeDilateTrackBar)

 originalWindow.ShowImage(image)
 processedImageWindow.ShowImage(processedImage)

 for {
 key := opencv.WaitKey(20)
 if key == 27 {
 os.Exit(0)
 }
 }

 os.Exit(0)
 }

References:

https://www.socketloop.com/tutorials/golang-gaussian-blur-on-image-and-camera-video-feed-examples

https://godoc.org/github.com/lazywei/go-opencv/opencv#Erode

http://docs.opencv.org/2.4.2/doc/tutorials/imgproc/erosiondilatation/erosiondilatation.html

http://docs.opencv.org/2.4.2/images/Morphology1TutorialTheoryOriginalImage.png

  See also : Golang : Gaussian blur on image and camera video feed examples



Tags : golang opencv erode dilate morphology

By Adam Ng

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