http://imagej.273.s1.nabble.com/Re-Signal-to-Noise-Ratio-SNR-tp3687073p3687074.html
what I can see with my eyes. I mean, in most cases the images with more
> Bonjour!
>
>
> Hi everyone,
>>
>> There's a MATLAB function called 'wiener2' that filters a 2D image and
>> also
>> estimates the additive noise power, which is kind of a signal-to-noise
>> ratio.
>>
>
> As you may have seen from the paper that I've recommended earlier (see
> below) this task is ill-posed. Of course, there are cases, i.e. images, for
> which sufficient estimates of the signal-to-noise ratio are possible.
> However, in order to construct a true Wiener-filter you need to know much
> more details than the simple signal-to-noise ratio. Simply spoken, you need
> to know it as a function of the spatial frequency. Getting estimates of this
> function is much more involved if it is at all possible.
>
> The approach taken in my paper is very simple, but for the described
> purpose it was sufficient. In the very case one can only speak of a very
> coarse approximation of a Wiener-filter because it was a low-pass with
> signal-dependent cut-off frequency. The cut-off frequency was set to the
> spatial frequency where the S + N was _approximately_ equal to N. Both S + N
> and N can sometimes be extracted from appropriate image regions...
>
>
> Does anyone in this list know if there is an ImageJ (or even a Java)
>> implementation of this filter and that also gives that sort of estimation?
>>
>
> I don't know of such an attempt...
> I should be very careful with software that promises to do the job and
> without exact knowledge of how the signal-to-noise estimates are determined.
>
>
> Thank you all very much.
>>
>> []s
>> --
>> Anderson Vinícius Alves Ferreira
>> Intern at Lafarge Centre de Recherche
>> 95 rue du Montmurier - 38291 St Quentin-Fallavier - France
>>
>
> Best
>
> Herbie
>
> =================================
>
>
> On 5 July 2010 13:35, Gluender <
[hidden email]> wrote:
>>
>> Bonjour,
>>>
>>> I agree with Joachim Wesner's statement but maybe the background of the
>>> original question is of some importance...
>>>
>>> In certain situations approximations, e.g.
>>>
>>> S + N / N
>>>
>>> may be of some help. See for instance:
>>>
>>> <
http://www.gluender.de/Writings/WritingsTexts/HardText.html#Gl-1980-1>
>>>
>>>
>>> Hi there,
>>>
>>>>
>>>> Sorry but measuring the SNR of a single image without reference or any
>>>> a-priori-knowledge is simply mathematically IMPOSSIBLE!
>>>>
>>>> How do you tell what is true data, what is noise? The human vision
>>>> system
>>>> might imply that it is still possible, but this relies on
>>>> implicit assumptions about object structure and spatial frequency
>>>> spectrum
>>>> of the "true" data.
>>>>
>>>> Mit freundlichen Grüßen / Best regards
>>>>
>>>> Joachim Wesner
>>>> Projektleiter Optik Technologiesysteme
>>>>
>>>> Leica Microsystems CMS GmbH | GmbH mit Sitz in Wetzlar | Amtsgericht
>>>> Wetzlar HRB 2432
>>>> Geschäftsführer: Dr. Stefan Traeger | Dr. David Roy Martyr | Colin
>>>> Davis
>>>> www.leica-microsystems.com
>>>>
>>>> ---------------------
>>>>
>>>> Hi,
>>>>
>>>> Is there any ImageJ plugin to calculate the Signal-to-Noise Ratio of a
>>>> single image without a reference image?
>>>>
>>>> I've seen some plugins that calculate the SNR of images but in all of
>>>> them
>>>> reference images are necessary.
>>>>
>>>> Thank you.
>>>>
>>>> []s
>>>> --
>>>> Anderson Vinícius Alves Ferreira
>>>> Intern at Lafarge Centre de Recherche
>>>> 95 rue du Montmurier - 38291 St Quentin-Fallavier - France
>>>>
>>>>
>>> Best
>>> --
>>>
>>> Herbie
>>>
>>> ------------------------
>>> <
http://www.gluender.de>
>>>
>>>