Computer Generated Images (CGI) have developed in character and potential use within Hollywood cinema in line with the ongoing evolution of both hardware and software. Alongside this there has been a parallel development of dominant ideas of what CGI represents and how it should be read. This last is of paramount importance to this study, because as we shall see, how the audience reads the CGI depends entirely upon its exposure to the accompanying technological and cultural movements in media and entertainment industries. For example, a young audience, brought up within a techno-culture involving video gaming, music television, and involving many precedents of CGI in cinema, has now come to expect certain generic and cultural signifiers within the Computer Generated Image. Through exposure to documentary footage of the film's production, or access to the director/producer's commentary on the meaning of the images on screen, a system of revelation and contemplation is set in motion: the spectator's eye is trained to "spot" the CGI. This article primarily addresses the period of development during the late 1980s/early 1990s, when Hollywood was still suspicious of the market potential of a technology which was underdeveloped, expensive, and conspicuous. This conspicuousness needs to be addressed in terms of the use of CGI, particularly within the sf genre. Sf, as a genre, draws attention to its own form via the spectacle, and CGI technology not only allows the film maker the means to create imagery not previously possible, but also in true sf tradition, the technology used to make up the sf narrative alerts the audience to that spectacular technology. The conspicuousness of CGI is part of Hollywood's on-going struggle to convey realism (both in a photoreal sense, and in fiction presented as fact) in its cinema. This struggle will be examined in this article as the struggle for control, and will be addressed as an implication of the various modernist attitudes towards progress and innovation as a key value system of modernity. By manipulating an image digitally, or by creating an image from scratch, the filmmaker is asserting a control over the image, which affords a control over the degree of chance and gravity never before attained in mainstream moving image production. This "progress" in the use of CGI has come to fruition in the last five or six years, as producers defy the audience to spot the difference between CGI and the photographed image. This, of course, also has implications which feed back into the audience's ability to "read" the CGI text as Computer Generated--as opposed to Filmic--Image. The ways in which the blockbuster is promoted, for example, and the audience's prior knowledge of how the film was put together via trailers, "making-of' TV specials, Internet spoilers, cross-promotional strategies, as well as "director's commentaries" on DVD contribute to an extra-textual knowledge which is a crucial factor in the individual's consumption of the text.