Unbiased rendering

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In computer graphics, unbiased rendering or photorealistic rendering are rendering techniques that avoid systematic errors, or statistical bias, in computing an image’s radiance. Bias in this context means inaccuracies like dimmer light or missing effects such as soft shadows, caused by approximations. Unbiased methods, such as path tracing and its derivatives, simulate real-world lighting and shading with full physical accuracy. In contrast, biased methods, including traditional ray tracing, sacrifice precision for speed by using approximations that introduce errors—often seen as blur.^[1] This blur reduces variance (random noise) by averaging light samples, enabling faster computation with fewer samples needed for a clean image.^[2]