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In statistics, the Anscombe transform, named after Francis Anscombe, is a variance-stabilizing transformation that transforms a random variable with a Poisson distribution into one with an approximately standard Gaussian distribution. The Anscombe transform is widely used in photon-limited imaging (astronomy, X-ray) where images naturally follow the Poisson law. The Anscombe transform is usually used to pre-process the data in order to make the standard deviation approximately constant. Then denoising algorithms designed for the framework of additive white Gaussian noise are used; the final estimate is then obtained by applying an inverse Anscombe transformation to the denoised data. ==Definition== For the Poisson distribution the mean and variance are not independent: . The Anscombe transform〔 〕 : aims at transforming the data so that the variance is set approximately 1 whatever the mean. It transforms Poissonian data (with mean ) to approximately Gaussian data of mean and standard deviation 1. This approximation is valid provided that is larger than 4. 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Anscombe transform」の詳細全文を読む スポンサード リンク
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