Add a centerline to a series of .jpg images

Question

Does anyone have any suggestions on programs or code to add a permanent dashed centerline or Rectangle to a series of.jpg images. Either using ImageJ or IrfanView or R

EDIT. The suggestion of using the ImageMagick package in R is great and one image works well using the below code. But it's unclear how this can be batch performed on multiple images in a folder.

> test <- image_read('F:/11_Cairns/Data/2_Barron_Richter_Thomatis/FRAMES/2017_4_665_20171206083500_6.jpg')
> img <- image_draw(test)
> rect(600,0, 680, 720, border = "yellow", lty = "dashed", lwd = 2)

Answer 1

The following will work...

# Return a vector of all file paths that end with "jpg":
files <- list.files("F:/11_Cairns/Data/2_Barron_Richter_Thomatis/FRAMES/", pattern = "jpg$", ignore.case = TRUE, full.names = TRUE)

# Loop over each image and add a dashed yellow lines.
for(i in files){
    test <- image_read(i)
    img <- image_draw(test)
    rect(600, 0, 680, 720, border = "yellow", lty = "dashed", lwd = 2)
    dev.off()
    # And if you want to save it, but not overwrite the original file:
    file_loc <- gsub("\\.jpg", "_new.jpg", i, ignore.case = TRUE)
    image_write(img, path = file_loc, format = "jpg")
}