11、Shrink or enlarge images at the command line(在终端中调整图片大小)
you’ll need to install it via Synaptic (search for and install imagemagick)
For example, the following will shrink filename.bmp to half its original size:

    convert -resize 50% filename.bmp filename_small.bmp

The following will enlarge filename.bmp to twice its original size (although there will be an obvious degradation in quality):

    convert -resize 200% filename.bmp filename_larger.bmp

PS:图像需事先放到home 文件夹下