Automatic noise estimation from the multiresolution support

We describe an automated approach for determining the noise associated with astronomical images. Detector noise is ever present and must be determined for high-quality image filtering or compression. We also show that the method can be used for very high quality cosmic-ray hit removal. Our method is based on a multiresolution transform of the image, the à trous wavelet transform. We present a range of examples and applications to illustrate the effectiveness of this approach.