Cropping

vipsthumbnail normally shrinks images to fit within the box set by --size. You can use the --smartcrop option to crop to fill the box instead. Excess pixels are trimmed away using the strategy you set. For example:

$ vipsthumbnail owl.jpg --smartcrop attention -s 128

Where owl.jpg is an off-centre composition:

Gives this result:

First it shrinks the image to get the vertical axis to 128 pixels, then crops down to 128 pixels across using the attention strategy. This one searches the image for features which might catch a human eye, see vips_smartcrop() for details.