[OpenCV] Chapter02-04 Manipulating image channels

Manipulating image channels

Source Code

package main

import (
 "gocv.io/x/gocv"
 "log"
)

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

 image := originalMat.ToBytes()
 width := originalMat.Rows()
 height := originalMat.Cols()
 channel := originalMat.Channels()

 // swap red and blue(BGR)
 for row := 0; row < width; row++ {
  for col := 0; col < height; col++ {
   index := (width*row + col) * channel
   image[index], image[index+2] = image[index+2], image[index]
  }
 }

 matForSwap, err := gocv.NewMatFromBytes(width, height, gocv.MatTypeCV8UC3, image)
 if err != nil {
  log.Panic("Can not swap red and blue", err)
  return
 }

 windowForSwapRedAndBlue := gocv.NewWindow("Swap red and blue")
 defer windowForSwapRedAndBlue.Close()
 windowForSwapRedAndBlue.IMShow(matForSwap)

 // back to original and scale
 for row := 0; row < width; row++ {
  for col := 0; col < height; col++ {
   index := (width*row + col) * channel
   image[index], image[index+2] = image[index+2], image[index]

   // blue scale
   scaleForBlue := float32(image[index]) * 0.9
   image[index] = uint8(scaleForBlue)

   // green scale
   scaleForGreen := float32(image[index+1]) * 1.1
   image[index] = uint8(scaleForGreen)
  }
 }

 matForScale, err := gocv.NewMatFromBytes(width, height, gocv.MatTypeCV8UC3, image)
 if err != nil {
  log.Panic("Can not scale", err)
  return
 }

 windowForScale := gocv.NewWindow("Scale Image")
 defer windowForScale.Close()
 windowForScale.IMShow(matForScale)

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

Execute Result