[IPOL announce] new preprint: Analysis and Extension of the Ponomarenko et al Method, Estimating a Noise Curve from a Single Image

[announcements about the IPOL journal]

A new preprint is available in IPOL: http://www.ipol.im/pub/pre/82/

Analysis and Extension of the Ponomarenko et al Method, Estimating a 
Noise Curve from a Single Image
     by Miguel Colom, Antoni Buades

    Abstract

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.



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