Crop a set of images
batch_crop left top width height image1 image2 ...
The area defined by the rectangle left, top, width, height is cropped out of each of the images and saved in a file of the same name, but prefixed by "crop_".
batch_crop 10 10 100 100 fred.jpg jim.png
will make two images, crop_fred.jpg and crop_jim.png, each of 100 by 100 pixels, taken from the corresponding input images.
returns 0 on success and non-zero on error.
vipsheader(1), im_vips2tiff(3), im_vips2jpeg(3), im_vips2png(3), im_vips2ppm(3)