Posted by
Joel Sheffield on
URL: http://imagej.273.s1.nabble.com/Removing-grill-grate-horizontal-stripes-in-background-tp5009203p5009216.html
@Kiwa
I'm glad that it was helpful. I chose the value of 34 just by trying
several different sizes to see what would work. You might do better to try
some others as well. Actually, the filter is removing the lower
frequencies. In the FFT display, the highest frequencies are towards the
center. That display is also rotated 90 degrees from the image, so you
could experiment with an oval, rather than a circle to see if you get more
clarity of the samples. I tried it, but the image preserved the vertical
grid lines. Not so useful.
As far as speed is concerned, You might try a lower resolution
image....fewer pixels to process.
Joel
Joel B. Sheffield, Ph.D
Department of Biology
Temple University
Philadelphia, PA 19122
Voice: 215 204 8839
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On Thu, Aug 14, 2014 at 1:21 PM, Kiwa <
[hidden email]> wrote:
> @Joel :
> Hi Joel,
> Thanks for your response.
> With some other operations with your image as a starting point I got this
> :
>
> <
>
http://imagej.1557.x6.nabble.com/file/n5009210/Inverse_FFT_of_Food_processed.jpg> >
>
> This kind of result is fine, since I can get the coverage of the food on
> the
> belt from an histogram.
> However, FFT and inverse FFT seems to take some time, so it maybe not fit a
> live camera feed.
> But it is still a nice first solution for my problem !
>
> How did you choose to use R=34.4 ?
> Since my goal is to make it automatic for every frame of a video, I wonder
> if I can put it as a parameter.
> Does it mean that the filter is cutting small frequencies (ie small edges?)
> ?
> Is it already filtering only horizontal small frequencies ? if not, is
> there
> any other selection filter (your circle) that I can use to cut only the
> horizontal line ?
>
> Thanks again!
>
> @Michael :
>
> Thanks for your advice.
> /(3) have the same light intensity in all of the image (currently, it gets
> much darker towards the back).
> /
> I will take more precaution with my footage.
> Put the camera directly above the belt. I will probably process only the
> center region of the picture since the shadow in the back is getting the
> region much darker.
> /(2) have the background as dark as possible (block light that would
> illuminate background objects below the grid) /
> I unfortunately can't change the background.
>
> /(1) with light from left and right only, you should be able to eliminate
> the reflections on the grid
> /
> That's interesting ! Is there any particular good way to install the light
> from left/right to avoid reflections ?
>
> Thanks again !
>
>
>
> Regards,
> Kiwa.
>
>
>
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