Because the position and the size of irises in images are not fixed, these reasons result in that the computing burden increases and the iris boundary localization is slow.

虹膜在图像中的位置和大小不固定，这使得虹膜边界定位计算量大，定位速度慢。

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The iris is fixed to the ciliary body.

虹膜固定在睫状体上。

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