Functions file for size:

add_image_size( 'custom-size', 220, 180 ); // 220 X 180, soft proportional crop mode
add_image_size( 'custom-size', 220, 180, true ); // 220 x 180 , hard crop mode
add_image_size( 'custom-size', 220, 220, array( 'left', 'top' ) ); // Hard crop left top

x_crop_position accepts ‘left’ ‘center’, or ‘right’.
y_crop_position accepts ‘top’, ‘center’, or ‘bottom’.