Filtrer une image en fonction d'une ou plusieurs couleurs

filter_img <- function(img,type="r",grey=F){  

 if (grey==F) {

  temp <- img

  if (type == "r"){temp [,,2] <- 0 ; temp[,,3] <- 0

  } else if ((type == "v")|(type == "g")){temp [,,1] <- 0 ; temp[,,3] <- 0

  } else if (type == "b"){temp [,,1] <- 0 ; temp[,,2] <- 0

  } else if ((type == "rv")|(type == "vr")|(type == "gr")|(type == "rg")){temp[,,3] <- 0

  } else if ((type == "rb")|(type == "br")){temp[,,2] <- 0

  } else if ((type == "vb")|(type == "bv")|(type == "gb")|(type == "bg")){temp[,,1] <- 0  }

 } else if (grey==T) {

  if (type == "r"){temp <- img[,,1]

  } else if ((type == "v")|(type == "g")){temp <- img[,,2]

  } else if (type == "b"){temp <- img[,,3]

  } else if ((type == "rv")|(type == "vr")|(type == "rg")|(type == "gr")){temp<- (img[,,1]+img[,,2])/2

  } else if ((type == "rb")|(type == "br")){temp<- (img[,,1]+img[,,3])/2

  } else if ((type == "vb")|(type == "bv")|(type == "gb")|(type == "bg")){temp<- (img[,,2]+img[,,3])/2}}

return(temp)}

# Pour ouvrir une image

library("png") ; img1<-readPNG("png.png")