Graphic designer using pictures of animate objects in his designs

I am a Graphics Designer. I have been working on the software called Illustrator. This software is used to make logo, portraits and many other designs.

I work for different clients all over the world. In almost all the projects I have to make a picture of a human, animals and plants to make it attractive. But I came to know from somewhere that making these designs is forbidden in Islam. If yes, then why taking pictures is allowed?

I hope to get a detailed answer. If this is really forbidden then please suggest what I can create. I think in these ages its difficult to run away from pictures and drawings since they are every where.