Sharpen and Blur

The sharpen and blur filters can be used to nudge an image more to the photographer liking.

The Sharpen filter is quite common, and can be used to add a little more "crisp" edges to the image. The sharpen filter is quite impressive, but sometimes suffers from some image noise as a side effect.

The blur filter is far more useful than it is given credit for. Used carefully with selection masks, the blur filter can make "out of focus" effects.

Step-By-Step: Sharpen

1. open sample image

2. open sharpening filter

3. notice the effect on the image, click undo and repeat if necessary

4. Experiment with the other sharpen options.

Step-By-Step: Blur

1. open sample image

2. open blur filter

3. set the blur radius

4. note effect on image

5. experiment with differant blur values

Practical Tips

sharpening noise - be careful not to over-sharpen. For example, if you use the sharpen-more command twice (sometimes even once!) you may notice some noise artifacts.

selective blur - The blur filter is most useful in combination with selection masks. It is rarely useful to blur the entire image, but applying the effect to a specific area can be quite useful.