So, for example, the design for the cover of Reader's Digest was found to be protected by copyright despite being composed only of type and color. The unpleasant shock of seeing plagiarized work may suddenly make the copyright law a part of everyday life. The test is whether an ordinary observer, viewing the original work and the allegedly infringing work, will believe that copying has occurred. It is important to understand that style is not copyrightable. To work in the style of another designer is not a copyright infringement.
Infringement requires copying.
The wise infringer will, of course, attempt to change the work so that an ordinary observer does not see how copying could have occurred. A problem is that the infringers are often other illustrators or designers. The type of slavish copying this encourages, whether done with a Lucy or by scanning and digitizing an image, carries an enormous likelihood of copyright infringement. If you haven't already registered your work with the Copyright Office, do so immediately. Copyright registration is easy and inexpensive.