Self concept - Defined as the mental image you have of yourself, based on past and future events. Some of these events have a permanent effect on your self concept.
Self-Image - Another way of saying the same thing, no doubt but different people use different words to mean the same thing. It takes into consideration the way others think of us as well. What words do you use to describe yourself when no one is listening? Those words encompass your self - image.
Self perception - An awareness of one's self, the characteristics that make up your self. What attitudes result in what behaviours?
All three talk about knowing one's self. They are not confined to self-criticism or self-loathing which can be where a lot of people end up when looking at one's own characteristics. It is knowing one's self and choosing the things that work best for us.
Our self-concept can build us up if we become aware of our innermost thoughts and control them.