4.1.2. Demo of a simple blur

Demo

1. Open lena.png.
2. Select <Image> -> Filters -> Generic -> "Convolution Matrix..."
3. Set the 9 middle squares to 1, the other squares to 0 and the divisor to 9.
   (What we are doing is replacing every pixel with the average of its 3*3 neighbourhood.)
4. Press the "OK" button.
5. Repeat several times with Alt+F (or <Image> -> Filters -> "Repeat Last" ) to strengthen the effect.