crop.img: Crop an image
In ckenaley/trackter: Automated Kinematic Analysis of Image Data

Crops an image or images with a rectangle

crop.img(
  img = NULL,
  ul = NULL,
  br = NULL,
  out.dir = NULL,
  type = NULL,
  locate = FALSE
)

`img`	character, a path to an image file or directory containing images.
`ul`	numeric, the upper-left xy position of the rectangle in pixels.
`br`	numeric, the bottom-right xy position in pixel.
`out.dir`	character, the directory to which the image will be saved.
`type`	character, image type (optional). Must be: "jpeg", "png", or "tiff (case ignored)." If missing, file format is automatically determined by file name extension(s).
`locate`	logical, if TRUE and the 'img' is a single file path, the original image is printed to the graphics device and the user picks `ul` and `br` (in that order) with the cursor and two clicks of the mouse. If TRUE, the coordinates of the points picked by the user are returned. Ignored is 'img' is a directory containing images.

#retrieve image in system
 y <-system.file("extdata/img", "sunfish_BCF.jpg", package = "trackter")
od <- paste0(tempdir(),"/cropimg")
dir.create(od)

#display original
EBImage::display(EBImage::readImage(y),method="raster")

# crop and save as orignal format
crop.img(img=y,ul=c(5,30),br=c(100,200),out.dir=od)

# crop and save as png
crop.img(img=y,ul=c(5,30),br=c(200,200),out.dir=od,type="png")

#display cropped images
EBImage::display(EBImage::readImage(paste0(od,"/sunfish_BCF.jpg")),method="raster")
EBImage::display(EBImage::readImage(paste0(od,"/sunfish_BCF.png")),method="raster")

#clean up
unlink(od,recursive=TRUE)

# use graphics device to choose crop margins
## Not run: 
crop.img(img=y,out.dir=od,locate=TRUE)

## End(Not run)