Cool Stuff

Emerging Capabilities Image Processing Massively Multipass

Image Processing Scene Post-Processing –Light Blooms –Depth of field –Posterization Traditional Stuff –Convolution Filters –Frequency Space Operations

Convolutions Filter Mask Application –Implemented by shaders –Spill Intermediates to Float Buffers –Sped up by Using Separable Filters

Fourier Transform Transformation from image space to frequency space –Allows complex filtering Large convolutions Frequency limiting filters –Band limit –Band Pass –Band Stop

Fourier Transform by GPU Multipass algorithm Uses floating point textures Uses floating point destinations Real-time on 512x512

Fourier Transform Cnt’d Decimation in time algorithm Requires –Log2(width) + log2(height) + 2 passes

Fourier Passes Horizontal scramble –Rearrange pixels in rows Log2(width) horizontal butterflies –Complex multiply accumulates Vertical scramble –Rearrange pixels in columns Log2(height) vertical butterflies –Complex multiply accumulates

Massive Multipass Implement Complex Algorithms –Apply Shaders to Temporary Float Buffers –Prelude to the Future High-level Shading Languages F-Buffers

Questions?