I am not a graphic designer but I do some small graphics work occasionally and i use gimp.as you know its free to use. If my main job was graphic design I would definitely get Photoshop as soon as I can (maybe do a few small projects with GIMP so I can afford photoshop).
Hello Sumi Ariani! I think this is a common issue, When you are going to choose a low resolution image there in Gimp and Photoshop. By the way, you can check this link, I've found something for your query.. How to Change Image Resolution Using GIMP? http://guides.lib.umich.edu/c.php?g=282942&p=1888164
Yes you can Maiyan! I think this is an unique creativity to turn a photo into a cartoon. I've seen some useful Gimp tutorials on it. You can try them.