+data/camels.pexels-4321178.jpg:
+ tools/wget-ifmodified https://images.pexels.com/photos/4321178/pexels-photo-4321178.jpeg $@
+data/camels.jpg: data/camels.pexels-4321178.jpg
+ tools/mkimgthumb --jpg 800x400 'data/camels.smaller:-area:0x225.jpg' .
+