What you describe may well be copyright or trademark infringement. For example, copyright law gives the copyright owner the right to control "derivative" works, or works based on or adapted from the copyrighted work. If the logo you create is recognizable as having been derived from the original, it therefore may represent copyright infringement. The best way to proceed is to take samples of what you propose to an intellectual property attorney, who can review them in detail, evaluate whether they infringe, and possibly propose changes to avoid infringement.