[OpenCV] Chapter02-09 Equalizing image histogram

Equalizing image histogram

Source Code

package main

import (
 "fmt"
 "gocv.io/x/gocv"
 "gonum.org/v1/plot"
 "gonum.org/v1/plot/plotter"
 "gonum.org/v1/plot/vg"
 "log"
)

func main() {
 imageFilePath := "../../data/Lena.png"
 originalMat := gocv.IMRead(imageFilePath, gocv.IMReadGrayScale)
 if originalMat.Empty() {
  log.Panic("Can not read image: " + imageFilePath)
  return
 }

 // grey equalizeHist
 greyEqualizeHistMat := gocv.NewMat()
 gocv.EqualizeHist(originalMat, &greyEqualizeHistMat)

 windowForGreyEqualizeHist := gocv.NewWindow("Window For Grey EqualizeHist")
 defer windowForGreyEqualizeHist.Close()
 windowForGreyEqualizeHist.IMShow(greyEqualizeHistMat)

 // plot
 greyEqualizeHistImage := greyEqualizeHistMat.ToBytes()

 v := make(plotter.Values, len(greyEqualizeHistImage))
 for i := 0; i < len(v); i++ {
  v[i] = float64(greyEqualizeHistImage[i])
 }

 plot, err := plot.New()
 if err != nil {
  log.Println("Can not create plot", err)
  return
 }

 plot.Title.Text = fmt.Sprintf("pixel value")

 histogram, err := plotter.NewHist(v, len(v))
 if err != nil {
  log.Panic("Can not create histogram", err)
  return
 }

 histogram.Normalize(1)
 plot.Add(histogram)

 if err := plot.Save(4*vg.Inch, 4*vg.Inch, "pixel_value.png"); err != nil {
  log.Panic(err)
  return
 }

 // wait
 for {
  key := gocv.WaitKey(3)
  if key == 27 {
   log.Println("Pressed ESC")
   break
  }
 }
}

Execute Result