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Item Simulating Film Grain using the Noise-Power Spectrum(The Eurographics Association, 2007) Stephenson, Ian; Saunders, Arthur; Ik Soo Lim and David DuceFilm grain is an essential part of real images. The artifacts it introduces add character to images, which can otherwise appear too perfect. This paper considers the synthesis of film grain based upon its noise-power spectrum, producing grain fields which approximate real film over a range of enlargements and densities. We also identify limitations of the noise-power spectrum in that it fails to fully characterize grain. Simulated grain fields have spectra which match real grain, but lack the phase and density correlations required to create the appearance of individual grains at high magnifications.Item Interactive Relighting for Stage Use(The Eurographics Association, 2009) Stephenson, Ian; Wen Tang and John CollomosseRe-lighting by combining images taken under known lighting conditions to synthesise new lighting configurations is a simple, but powerful technique capable of producing impressive results. However it has found little practical application. Here we demonstrate the integration of a relighting tool into a typical theatrical lighting system, to provide real time previews both offline when the stage is unavailable, and during performance.Item Hardware Accelerated Shaders Using FPGAs(The Eurographics Association, 2009) Goddard, Luke; Stephenson, Ian; Wen Tang and John CollomosseWe demonstrate that Field Programable Gate Arrays (FPGAs) can be used to accelerate shading of surfaces for production quality rendering (a task standard interactive graphics hardware is generally ill-suited to) by allowing circuits to be dynamically created at run-time on standard commercial logic boards. By compiling shaders to hardware descriptions, they can be executed on FPGA with the performance of hardware without sacrificing the flexibility of software implementations. The resulting circuits are fully pipelined, and for circuits within the capacity of the FPGA can shade MicroPolygons at a fixed rate independent of shader complexity.