<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div><span style="-webkit-text-size-adjust: auto; background-color: rgba(255, 255, 255, 0);">A new article is available in IPOL: <a href="http://www.ipol.im/pub/art/2013/45/">http://www.ipol.im/pub/art/2013/45/</a></span></div><div><span style="-webkit-text-size-adjust: auto; background-color: rgba(255, 255, 255, 0);"><br></span><span style="background-color: rgba(255, 255, 255, 0); ">Analysis and Extension of the Ponomarenko et al. Method, Estimating a Noise Curve from a Single Image</span><span style="-webkit-text-size-adjust: auto; background-color: rgba(255, 255, 255, 0);"><br>by </span><span style="text-align: left; background-color: rgba(255, 255, 255, 0);">Miguel Colom and Antoni Buades</span><span style="-webkit-text-size-adjust: auto; background-color: rgba(255, 255, 255, 0);"><br>Image Processing On Line, vol. 2013, pp. 173-197<br></span><a href="http://dx.doi.org/10.5201/ipol.2013.45">http://dx.doi.org/10.5201/ipol.2013.45</a><br><br><span style="-webkit-text-size-adjust: auto; background-color: rgba(255, 255, 255, 0);">Abstract</span><br><div style="text-align: -webkit-auto; "><span style="text-align: justify; background-color: rgba(255, 255, 255, 0);">In the article "An Automatic Approach to Lossy Compression of AVIRIS Images" N.N. Ponomarenko et al. propose a new method to specifically compress AVIRIS images. As part of the compression algorithm, a noise estimation is performed with a proposed new algorithm based on the computation of the variance of overlapping 8x8 blocks. The noise is estimated on the high-frequency orthonormal DCT-II coefficients of the blocks. To avoid the effect of edges and textures, the blocks are sorted according to their energy measured on a set of low-frequency coefficients. The final noise estimation is obtained by computing the median of the variances measured on the high-frequency part of the spectrum of the blocks using only those whose energy (measured on the low-frequencies) is low. A small percentile of the total set of blocks (typically the 0.5%) is used to select those blocks with the lower energy at the low-frequencies. Although the method measures uniform Gaussian noise, it can be easily adapted to deal with signal-dependent noise, which is realistic with the Poisson noise model obtained by a CCD device in a digital camera.</span></div></div><div style="text-align: -webkit-auto; "><span style="text-align: justify; background-color: rgba(255, 255, 255, 0);"><br></span></div><div style="text-align: -webkit-auto; "><span style="text-align: justify; background-color: rgba(255, 255, 255, 0);"><br></span></div><div><span style="-webkit-text-size-adjust: auto; background-color: rgba(255, 255, 255, 0);"><br></span></div><div><span style="-webkit-text-size-adjust: auto; background-color: rgba(255, 255, 255, 0);"><br></span></div></body></html>