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#' Title
#'
#' @slot image matrix.
#'
#' @return
#' @export
#'
#' @examples
imageOneChannel <- setClass("imageOneChannel", slots=list(imageMatrix="matrix"))
#' Is It A One Channel Image
#'
#' @description Checks if an object is of type \code{\link[Raspository]{imageOneChannel}}.
#'
#' @export
#'
#' @param x any R object.
#'
#' @return \code{TRUE}, if the object is of type \code{\link[Raspository]{imageOneChannel}}.
#' \code{FALSE} otherwise.
#'
#'
#' @examples
is.imageOneChannel <-function(x){
return(inherits(x, "imageOneChannel"))
}
#' Title
#'
#' @param pathToJpeg
#'
#' @return
#' @export
#' @importFrom jpeg readJPEG
#' @importFrom methods new
#'
#' @examples
imageOneChannelFromJpeg <-function(pathToJpeg){
image<- readJPEG(pathToJpeg)
imageOneChannel <- image[,,1]
return(new("imageOneChannel", imageMatrix = imageOneChannel))
}
#' Title
#'
#' @param object
#'
#' @return
#' @export
#' @importFrom grDevices as.raster
#' @importFrom graphics plot
#' @importFrom methods slot
#'
#' @examples
plot.imageOneChannel <- function(object){
plot(as.raster(object@imageMatrix))
}
#' Title
#'
#' @importFrom jpeg writeJPEG
#'
#' @param target
#' @param object
#'
#' @return
#' @export
#'
#' @examples
writeJPEG.imageOneChannel <- function(object, target){
writeJPEG(image = object@imageMatrix, target = target)
}
#' Title
#'
#' @importFrom png writePNG
#'
#' @param target
#' @param object
#'
#' @return
#' @export
#'
#' @examples
writePNG.imageOneChannel <- function(object, target){
writePNG(image = object@imageMatrix, target = target)
}
#' Title
#'
#' @export
#'
#' @import data.table
#'
#' @param img
#' @param log.scale
#'
#' @references \insertRef{Weickert2019}{Raspository}
#'
#' @return
#'
#'
#' @examples
calculateFourierSpectrum <- function(img, log.scale = TRUE, shift = TRUE){
if(shift){
## generate checkerboard sign imageMatrix to shift it in the fourier domain
DT <- CJ(1:nrow(img@imageMatrix), 1:ncol(img@imageMatrix))
DT[, sign := (-1)^(V1 + V2)]
shiftMatrix <- new("imageOneChannel", imageMatrix = as.matrix(dcast(DT, V1 ~ V2, value.var = "sign")[,-1]))
shiftedImg <- img * shiftMatrix
imgFTrans <- fft(shiftedImg@imageMatrix)
}else{
imgFTrans <- fft(img@imageMatrix)
}
## calculate the eiclidean norm
fourierSpectrum <- new("imageOneChannel",
imageMatrix = sqrt(Re(imgFTrans)^2 + Im(imgFTrans)^2))
## perform logarithmic rescaling
if(log.scale){
fourierSpectrum <- logarithmicDynamicCompression(fourierSpectrum)
}
return(fourierSpectrum)
}
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