A new article is available in IPOL: http://www.ipol.im/pub/art/2013/45/

Analysis and Extension of the Ponomarenko et al. Method, Estimating a Noise 
Curve from a Single Image
by Miguel Colom and Antoni Buades
Image Processing On Line, vol. 2013, pp. 173-197
http://dx.doi.org/10.5201/ipol.2013.45

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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