Kernel size
From The Glossary of Digital Photography
Relates to the number of pixels used when sampling during image manipulations, such as sharpening and interpolation. For example, when sharpening with unsharp masking, using a larger kernel size will increase the width of the edge-sharpening and enhancement effect, causing that effect to be more apparent. This may increase the apparent sharpness. Increasing it too much will tend to make an image appear to be over-sharpened.
