fftshift將零頻率移到中心搭伤，R語言imagefx包只怎，時序圖像特征識別
# Tue Oct 12 14:20:32 2021 edit
# 字符編碼：UTF-8
# R 版本：R 4.1.1 x64 for window 11
# cgh163email@163.com
# 個人筆記不負(fù)責(zé)任，拎了個梨????
#.rs.restartR()
require(imagefx )
rm(list = ls());gc()
? fftshift # 將零頻率移到中心
## build the four components of a matrix with four values (i.e. 1:4)
x1 <- matrix(1,nrow=1,ncol=1)
x2 <- x1+1
x3 <- x2+1
x4 <- x3+1
## combine all components together
x <- rbind(cbind(x1,x2),cbind(x3,x4))
## shift the matrix
x.shift <- fftshift(x)
## note the difference of the shifted and original
print(x)
print(x.shift)
##以圖形方式記錄移位和原始的差異
close.screen(all.screens=TRUE)
split.screen(c(1,2))
screen(1)
image(x,main='Original',col=rainbow(4))
screen(2)
image(x.shift,main='FFT Shifted', col=rainbow(4))
## close screens
close.screen(all.screens=TRUE)
fftshift將零頻率移到中心.png
