You must use a same-domain image.

Convolution

Name Matrix JS WGSL
Identity
0 0 0
0 1 0
0 0 0
Box Blur
1/9 1/9 1/9
1/9 1/9 1/9
1/9 1/9 1/9
Guassian Blur
1/16 1/8 1/16
1/8 1/4 1/8
1/16 1/8 1/16