Practicing with "NIR hyperspectral image analysis using R" - part 3 .(A.A.Gowen - NIR News)

Today I have been practicing with  part 3 of these nice tutorials about NIR hyperspectral image. The author (@eefieg) leaves some parts without code in order that the reader practice and get the same or similar results. For example compare two classification images obteined with two different methods, so if we substract one from the other, in the best of the cases, we would not see any frames, just a uniform color (the color which represents the zero value).

Finally I got (I think) the same residual image as Aoife, in the article.

 

r_PC1<-Im1_PC1[,]<= -2
r_PC1<-1*r_PC1         

g_PC1<-(Im1_PC1[,]> -2)&(Im1_PC1[,]<=0.7)
g_PC1<-3*g_PC1       

b_PC1<-(Im1_PC1[,])>0.7
b_PC1<-2*b_PC1       

col_PC1<-r_PC1+g_PC1+b_PC1
dev.new();
image(col_PC1)

diff<-col_PC1 - Im1_Class
dev.new();
image(diff)