# DoG filter for denoising

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## DoG filter for denoising

 Hi there, I'm using a DoG filter for the purpose of image denoising. Has some one a good technical paper about the use of this filter for denoising (not edge detection). I found some Wikipedia infos but I would appreciate something more specific on denoising. As far I now this filter behaves linearly so it is possible to still do intensity measurements. In my case i'm looking at the evolution of my signal over time. Thank you for your support, Fabrice. -- ImageJ mailing list: http://imagej.nih.gov/ij/list.html
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## Re: DoG filter for denoising

 Good day Fabrice, to me it is not perfectly clear what you intend to do. DoG means difference of Gaussians and this implies that this linear filter will--in simple terms--increase contrasts. In fact it acts as an isotropic and band-limited LaPlace-filter. The latter produces the second derivative of an image and, as a spatially discrete operator, can be formulated a like: 0  1  0 1 -4  1 0  1  0 If you apply this operator to an image (convolution) you will see that it extracts edges. The same holds for isotropic versions such as 1  1  1 1 -8  1 1  1  1 and finally for band-limited versions such as the DoG-operators. The disadvantage of the LaPlace-operator is, that it not only extracts edges but enhances noise as well. Band-limitation then will reduce the enhancement of high frequency noise. However the main purpose is to extract/enhance edges. DoG-filtering is _not_ for noise reduction, if you are not interested in edge-extraction/enhancement. You may experiment with test patterns to get an impression of these type of differentiating operations. HTH Herbie :::::::::::::::::::::::::::::::::::::::::::: Am 02.02.17 um 13:03 schrieb Fabrice Senger: > Hi there, > > I'm using a DoG filter for the purpose of image denoising. Has some one a > good technical paper about the use of this filter for denoising (not edge > detection). I found some Wikipedia infos but I would appreciate something > more specific on denoising. > > As far I now this filter behaves linearly so it is possible to still do > intensity measurements. In my case i'm looking at the evolution of my > signal over time. > > Thank you for your support, > > Fabrice. > > -- > ImageJ mailing list: http://imagej.nih.gov/ij/list.html> -- ImageJ mailing list: http://imagej.nih.gov/ij/list.html