There are many photo editing softwares such as Photoshop, Gimp etc. But they are very large in sizes and have too many facilities that we do not frequently use.
Here is a 365 kb software FotoGrafix which has the frequently needed options of other image editing softwares. It is free. You can apply layers, brush strokes etc. You can even process many images at the same time and it also provides command line support.
Download link
FOTOGRAFIX
