median filter

Submitted by guoe on Thu, 2012-06-07 07:16

Forums

Electron Microscopy and Image Processing

Hi All,

First of all thanks for any answer.

My question could seem silly but I cannot work it out. Basically, does a median filter affect the final resolution?

I am working in stain and boxing particles. I am using a median filter with kernel 5x5 in order to reduce noise and relief my eyes.
As expected after a median filter is applied, the edges look better. I was wondering whether those particles can be used for image processing and the median filter can help in aligning particles usless it does not affect the resolution.

Thanks

goue

Axel Thu, 2012-06-07 10:03

Hi Goue,

My understanding of the median filter (garnered from wikipedia) is that it is largely similar to an averaging step. Each pixel is replaced with the median of the surrounding pixels.
Naturally, this may affect your final resolution, depending on the final resolution that could be attained given the data quality, and sample.
The effect of a simple coarsening or binning will be much more predictable, in that it only affects the nyquist frequency attainable.
If you would prefer less noisy images, I would recommend using only binned images, using a binning factor appropriate for the target resolution. (A pixel size around 5 Angstrom should be more than adequate for negative stain data).

In short, I would not recommend using this filtered data for futher processing.

Axel