image processing

library(plyr)
library(dplyr)
library(tidyr)
library(magrittr)
xDim = 200
yDim = 200
rawImageArray = array(runif(xDim*yDim*3), c(xDim,yDim,3))
array2df <- function(arrayInput){
  dimImage = dim(arrayInput)
  data.frame(imageValues = as.vector(arrayInput),
    x = rep(1:dimImage[2], dimImage[3],,dimImage[1]),
    y = rep(1:dimImage[1], prod(dimImage[c(2,3)])),
    z = rep(1:dimImage[3],,, prod(dimImage[1:2])))
}
df2array <- function(dtInput){
  array(dtInput %>% arrange(z, x, y) %>% .$imageValues,
    c(max(dtInput$y), max(dtInput$x), max(dtInput$z)))
}

st = proc.time()
imageDF = array2df(rawImageArray) %>% tbl_df
meanFilter = list(xLen = 3, yLen = 3, Func = mean)
outList = vector('list', meanFilter$xLen*meanFilter$yLen)

x2 = -floor(meanFilter$xLen / 2):floor(meanFilter$xLen / 2)
y2 = -floor(meanFilter$yLen / 2):floor(meanFilter$yLen / 2)
xR = range(imageDF$x)
yR = range(imageDF$y)
k = 1
for (i in x2)
{
  for (j in y2)
  {
    outList[[k]] = imageDF %>% mutate(x = x+i, y = y+j) %>%
      filter(x >= xR[1], x <= xR[2], y >= yR[1], y <= yR[2]) %>% tbl_df()
    k = k + 1
  }
}
out = outList %>% llply(function(dt){
  gather(dt, variable, values, -x, -y, -z) %>% mutate(variable = as.character(variable))
  }) %>% bind_rows %>% tbl_dt(FALSE) %>% group_by(x, y, z, variable) %>%
  summarise(values = mean(values)) %>% spread(variable, values) %>% df2array
proc.time() - st
#   user  system elapsed
#   0.71    0.11    0.81

filterImage <- function(imgArray, imgFilter) {
  x <- dim(imgArray)[1]
  y <- dim(imgArray)[2]
  z <- dim(imgArray)[3]

  dx <- floor(dim(imgFilter)[1] / 2)
  dy <- floor(dim(imgFilter)[2] / 2)

  newImgArray <- array(0, dim = c(x, y, z))
  for (i in 1:x) {
    for (j in 1:y) {
      for (k in 1:z) {
        for (p in (0 - dx):(0 + dx)) {
          for (q in (0 - dy):(0 + dy)) {
            if (i + p < 1 || i + p > x || j + q < 1 || j + q > y) {
              next
            }
            newImgArray[i, j, k] <- newImgArray[i, j, k] +
              imgArray[(i + p), (j + q), k] * imgFilter[dx + p + 1, dy + q + 1]
          }
        }
      }
    }
  }
  newImgArray
}
imgFilter <- array(1/9, dim=c(3, 3))
st = proc.time()
filteredImageArray <- filterImage(rawImageArray, imgFilter)
proc.time() - st
#   user  system elapsed
#   6.33    0.07    6.81