Physical Computing

Table of Contents

Neighborhood processing
- Filtering (applying filter or mask to entire image):
- Correlation/convolution in an image:

In GUI browsers, I have this page themed dynamically, so when it's dark outside, you'll get a dark theme. You need JS enabled if you want the dynamic theme; I don't run any JS-based analytics or tracking.

Neighborhood processing

Value of pixel in output is determined by value of same pixel in input and the neighbours.

Use small neighbourhood of pixel in input to get new brightness value in output.

Filtering (applying filter or mask to entire image):

Mean filter — replace noise pixel by mean value of neighbours, including itself
Median filter — order values in increasing order including itself, find median, set that as new value

Correlation/convolution in an image:

works by scanning through image and applying mask (“kernel”) to each pixel
kernel is filled with numbers, not always equal to one (“kernel coefficients”)
coefficients weigh pixel value they are covering
output of correlation is sum of weighted pixel values
kernel alters center pixel
decreases size of image!

example kernels: