Graphic design is a discipline whose purpose is the creation of visual messages delivered to an audience, typically on behalf of a client. Practitioners of design are encouraged to demonstrate creativity in the execution of their work, and to develop and maintain awareness of visual culture to enable them to create works that are likely to be effective in their intended purpose. As a discipline involving communication between humans, the task is further complicated through the presence of many unknowns, poorly defined or emergent problems and constraints. Within this context, this thesis examines whether it is possible to support graphic designers during ideation through the provision of relevant images, with consideration of the influence on both creative output and process. In this work, a selection of literature is examined informing a background for understanding graphic design, creativity, visual language and predicted image effects, then further literature regarding identifying image needs is evaluated, together with methods applied by other researchers for evaluating design ideation. In addition, the prior work is identified suggesting theory, methods and results for determination of image needs, as well as the measurement of effects upon process. Developing from the reviewed literature, the thesis then presents full descriptions of methods applied and results obtained from three studies of design; the first study identifies specific roles that images are determined to play within the practice of professional graphic designers operating within New Zealand; the two following studies then examine the effects of supplying those images upon design output and process through laboratory experiments involving graphic design students working on typical graphic design tasks. Finally, the results of all three studies are discussed in relation to the research plan and literature; the thesis conclusion being that based upon the evidence, images representing the aesthetic tastes of the client and market do not consistently influence ideation output, however, they are shown to have a measurable influence upon the ideation process of the designer and that it is, therefore, possible to support design ideation through provision of images.