[Image-SIG] Remove noise from high ISO photos

Daniel Felix Ferber danielsforummail at terra.com.br
Wed Dec 19 13:57:33 CET 2007


Hi Carlos,

Thanks for the advice about median filter. I will do some experiments.

When taking a photo with high ISO on a digital camera, there will be 
many pixels that have a random color that is completely different color 
from the expected one. But the photo still has a good sharpness 
ImageMagic uses a stategy that is similar to the median filter: it looks 
at the neighborhood o a pixel. If the color of the pixel is considerably 
different from the color of adjacent pixels, then the color of the pixel 
is changed to a color close to the neighborhood. If not, the pixel is 
preserved.

It seems that the median filter always changes the color of the pixel, 
and I am afraid that the image might loose sharpness.

I already considered using bindings for gimp, but only found information 
about writing gimp plugins in python. Does the binding allow me to 
control gimp from a python script that I run on a bash console?

Best regards,
Daniel Felix Ferber

Carlos da Silva Santos escreveu:
> Daniel,
>
> I don't know much about high ISO noise, but a standard way of removing
> noise while preserving edges is using a median filter:
> http://www.pythonware.com/library/pil/handbook/imagefilter.htm
>
> If your goal is only running the whole pipeline from python, you might
> install the python bindings for Gimp and try to use the Gimp filter
> from python.
>
> I hope this helps.
>
> []s
>
> Carlos
>
>
>
> On Dec 19, 2007 2:05 AM, Daniel Felix Ferber
> <danielsforummail at terra.com.br> wrote:
>   
>> Hi!
>>
>> I was wondering if PIL has a filter or enhancement in order to remove
>> noise from photos that were taked with high ISO. Gimp and ImageMagic
>> both have such a feature and it work very good.
>> I tried to use SMOOTH or SMOOTH_MORE filter. But there are better
>> strategies to remove high ISO noise that try to preserve sharpness of
>> the image.
>> Currently I am calling ImageMagic from within my python script, but I
>> would prefer if PIL would handle it. Is this possible in current version
>> of PIL?
>>
>> Best regards,
>> Daniel Ferber
>> _______________________________________________
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>>
>>     
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