Golang : Gaussian blur on image and camera video feed examples

The following code examples demonstrate how to use Golang and OpenCV to apply Gaussian blur filter on static image and video feed from a web camera. The code are pretty straight forward and I've written these examples to help myself to understand how image filtering works. Hope you can find them useful as well.

Here you go!

Gaussian blur on static image:

---

 package main

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

 var (
 originalWindow = new(opencv.Window)
 blurredWindow  = new(opencv.Window)
 blurredImage = new(opencv.IplImage)
 image = new(opencv.IplImage)
 slider = 50
 )

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

 // don't want 0x0 kernel size
 if kernelSize%2 == 0 {
 kernelSize = kernelSize + 1
 }

 blurredWindow.SetTrackbarPos("Kernel Size : ", kernelSize)
 sigma := float64(0.3)*float64(float64(kernelSize-1)*float64(0.5)-1) + float64(0.8)

 // From http://docs.opencv.org/2.4/modules/imgproc/doc/filtering.html?highlight=smooth#cv.Smooth
 // Assuming param1 and param2 is to specify the kernel size
 // param3 for sigma
 opencv.Smooth(image, blurredImage, opencv.CV_GAUSSIAN, kernelSize, kernelSize, sigma, 0)

 blurredWindow.ShowImage(blurredImage)

 fmt.Printf("Kernel size  = %dx%d\n", kernelSize, kernelSize)
 }

 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()

 blurredImage = image.Clone()

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

 blurredWindow = opencv.NewWindow("Gaussian Blurred")
 blurredWindow.Move(200, 200)
 defer blurredWindow.Destroy()

 // start with kernel size 1x1
 blurredWindow.CreateTrackbar("Kernel Size : ", 1, slider, trackBar)

 originalWindow.ShowImage(image)
 blurredWindow.ShowImage(blurredImage)

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

 os.Exit(0)
 }

---

Gaussian blur on video feed from web camera:

---

 package main

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

 var (
 originalWindow = new(opencv.Window)
 blurredWindow = new(opencv.Window)
 webCamFrameImage = new(opencv.IplImage)
 webCamera = new(opencv.Capture)
 slider = 50
 kernelSize int
 )

 func BlurImage(image *opencv.IplImage) error {

 // don't want 0x0 kernel size
 if kernelSize%2 == 0 {
 kernelSize = kernelSize + 1
 }

 sigma := float64(0.3)*float64(float64(kernelSize-1)*float64(0.5)-1) + float64(0.8)

 blurredImage := image.Clone()
 defer blurredImage.Release()

 // From http://docs.opencv.org/2.4/modules/imgproc/doc/filtering.html?highlight=smooth#cv.Smooth
 // Assuming param1 and param2 is to specify the kernel size
 // param3 for sigma
 opencv.Smooth(image, blurredImage, opencv.CV_GAUSSIAN, kernelSize, kernelSize, sigma, 0)

 blurredWindow.ShowImage(blurredImage)

 blurredWindow.SetTrackbarPos("Kernel Size : ", kernelSize)

 fmt.Printf("Kernel size  = %dx%d\n", kernelSize, kernelSize)
 return nil
 }

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

 }

 func main() {

 // activate webCamera
 webCamera = opencv.NewCameraCapture(opencv.CV_CAP_ANY) // autodetect

 if webCamera == nil {
 panic("Unable to open camera")
 }

 defer webCamera.Release()

 fmt.Println("Press ESC button to quit. Must be on either one of the windows, not in terminal...")

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

 blurredWindow = opencv.NewWindow("Gaussian Blurred")
 blurredWindow.Move(200, 200)
 defer blurredWindow.Destroy()

 // start with kernel size 1x1
 blurredWindow.CreateTrackbar("Kernel Size : ", 1, slider, trackBar)

 for {

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

 if webCamera.GrabFrame() {
 webCamFrameImage = webCamera.RetrieveFrame(1)
 if webCamFrameImage != nil {
 originalWindow.ShowImage(webCamFrameImage)
 BlurImage(webCamFrameImage)
 }
 }
 }

 os.Exit(0)
 }

---

Image credits:

http://grapee.jp/en/67588

References:

https://socketloop.com/tutorials/golang-put-utf8-text-on-opencv-video-capture-image-frame

https://socketloop.com/tutorials/golang-select-region-of-interest-with-mouse-click-and-crop-from-image