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A Level Physics OCR B help?!

Hi,
I'm revising for my mocks in January (Oh God) and I'm stuck on something to do with Digital processing in Physics.

It says that there are two methods to smooth random noise in a picture.
1) Mean Smoothing
2) Median Smoothing

For mean smoothing it says "Take the mean average of all the pixels surrounding each pixel (and the pixel itself) as the value of the pixel of the smoothed image."

For median smoothing it just says to take the median but the median of what oh my goodness I'm so confused! :confused:

I'm not too sure how this:

Becomes this:
---> Mean Smoothing

and

<--- for Median smoothing?!

Please help me I hope I made some sense! :confused:

THANK YOU

Reply 1

Stonebridge

Take the median of the pixels immediately around the one you're interested in.
The same as for taking the mean(average) of the pixels.

Do you know the difference between mean and median?

Mean
For example, take the pixel on the bottom left with a value of 185
It's surrounded by 5 zeros
Take the mean
185 + 0 + 0 + 0 + 0 + 0 = 185
Divide by 6 gives 31 (to 2 sig figs)
The 185 pixel is replaced by one of value 31

And so on...

(edited 10 years ago)