I suspect you mean to find a term to describe your software (as being easy and powerful) rather than the image, which is presumably not being generated by your software. In that case, you're likely intending top use a phrase like "image processing" or "image uploading" instead of "images".
At its core, I think your question is describing a common quandary in modern software marketing: the natural correlation between the two most common connotations of the term "simple" when used to describe software. It can be used to mean "easy to use", but it can also be used to mean "lacking power or complexity". It is often hard to find a term which implies the former without implying the latter. Even "easy to use" itself has unfortunate connotations of lack of power.
The most common term I've seen used in this context is intuitive, which implies ease of use without bringing any connotations of lack of functionality or power. It doesn't itself also imply any particular level of power, so it doesn't actually connote "powerful", but by the absence of a connotation of weakness it can feel more powerful in marketing language. It certainly sounds more elegant, advanced, and valuable.