The Canon S3 IS has the ability to select one of five sharpening settings, and I have been experimenting to figure out which one to use. The real question I have is which setting gives the best results after post processing, and is post-processing worth the trouble?

So I shot some test pictures. Here are reduced versions of the images:
   
   
All the original and adjusted images are posted to the Sharpness gallery. They are taken at ISO 100, f4.5. Those marked "low sharp" are with the camera set at its lowest sharpening setting, those marked "med sharp" are with the setting in the middle, and those marked "high sharp" are at the maximum. The suffixes: "50" = 50% at one pixel; "100" = 100% at 1 pixel; "100 2" = 100% at 2 pixels.

To change the sharpness settings on the Canon S3 you go into the Function menu, then scroll down to My Colors. One click left gets to the Custom settings and you can hit Set to make changes. Scroll up and down to Sharpness and select the amount.

The first thing I see is that the high setting is too sharp. There are halos everywhere. See these 100% clips:
         
Now compare that last one with the low sharpening fence picture:

and with the medium sharpening one:

The medium one is not bad at all, and the low sharpening one is too soft. How much can I improve the images, and is it worth it?

Using Aperture's default sharpening setting of 50% 1 pixel, I sharpened the low and medium sharp fence pictures. Then I changed the setting to 100% and sharpened the low sharp fence picture, and finally tried a radius of two pixels:

First medium at 50%, 1 pixel:

Then low at 50%, 1 pixel:

Low at 100%, 1 pixel:

And finally low 100% at 2 pixels:

Scaled to screen size, I prefer the second to last one. It has slightly more noise than the second one, but the sharpness looks good.

One thing I discovered is that the size of the final image affects the effect of the radius of the sharpening filter. Viewed at about 25% full size, the low sharpness fence and trike pictures look best with 100% at 2 pixels.

One side effect of the sharpening in Aperture at 2 pixels is that it creates more noise than the high setting of the camera and results in a lot of 100% black pixels, something that the camera does not do. The result is that the Aperture-sharpened images have a better contrast than the camera-sharpened images at the expense of noise.

Boosting medium sharp images to 100% 2 pixels resulted in oversharpening. Playing with the images at likely viewing resolutions I ended up preferring the low sharpness setting of the camera and using 100% intensity at between 1 and 2 pixels. So I think that it is worth using the lowest sharpening setting of the camera and the post processing. Aperture makes it easy and to generate new versions and fast to apply sharpening, even on my imac G5.

See all the images in the sharpness gallery.

Tags: Canon, S3, Sharpness