As I understand it, in image processing, when it is desired to apply a filter of some sort to an 2D image, a kernel is applied to all the pixels of the 2D image in a process called convolution. Median, Gaussian, Bilateral, all are examples of kernel. These kernels are applied in a similar fashion to that shown in this example http://www.songho.ca/dsp/convolution/convolution2d_example.html (which I found here, searching Signal Processing at StackExchange).
Is there a good list of all/many/most kernels, there uses, and an example before/after image?
Also, is it correct to say that all kernels are just matrices which get convolved against a source?