# Image Data

Formats:

also:

• https://www.youtube.com/watch?v=C_zFhWdM4ic How filters work, with box blur and Gaussian blur as examples.

Box Blur is done by a Normal Unity Kernel Convolution. Unity meaning that every element of the kernels matrix is 1. Normal meaning the pixels are then averaged by dividing each by the absolute sum of all the pixels in the matrix.

Gaussian Blur uses a matrix where the edge values are 1, but the values closer to the center follow a Normal distribution. A simple example might be:  1 2 1 2 4 2 1 2 1

• https://www.youtube.com/watch?v=uihBwtPIBxM How the Sobel edge detection filter works. Including finding the angle of the edge.+ This provides both the edge, and the angle of the edge. It uses Kernel Convolution with two matrixs, one applied to find horizontal edge, and another for vertical.
 -1 -2 -1 0 0 0 1 2 1
 -1 0 1 -2 0 2 -1 0 1

These are then combined into a single result by squaring the value of each pixel from the X result, adding that to the square of the corrisponding pixel in the Y result, and then taking the square root of that. We can also take each Y pixel and divide it by the X pixel then take the arc tangent of that to find the angle of the edge at that point.

• https://www.youtube.com/watch?v=sRFM5IEqR2w The Canny edge detection filter adds on to Sobel by thinning all the edges to 1 pixel by looking for local maximum pixels along the direction of the edge. It then removes weak edges via hysteresis thresholding. Two thresholds are set, and edges above the top one are kept, edges blow the bottom are removed, and edges between are kept if they are next to a kept edge.

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