that is a very tricky question!
First of all: Apple recommends to use "edge sharpening" and not "sharpening" with AP3; the "sharpening" is kept only for compatibility with AP2, so that adjustment made in previous versions still work.
The effect of edge sharpening really depends on your picture, and the defaults are quite good for standard pictures with a decent contrast and little noise.
Unfortunately, you often need the sharpening brush, for example, when it was difficult to take a good shot in the first place - poor light, poor contrast, and a bad signal to noise ratio. Also, Aperture's edge sharpening is not designed to correct unsharpness caused by a wrong focus or small depth of field or motion blur, its only purpose is to mitigate blur caused by the camera’s demosaic filter, but that sould not keep you from using it for other effects too.
What a sharpening filter does, is generally to measure locally the variance in luminance, estimated by the steepness (gradient) of the edge and to emphasize this steepness. The Aperture edge sharpening filter tries to distinguish between luminance variations caused by noise, and luminance variations caused by image structures (edges). The noise reduction filters use the same technique and both filters interact.
The three parameters in the Inspector HUD: As I said, the default settings are not bad for standard situation.
- Intensity: The amount of correction you want - just try it out, it really depends on your taste. Values larger than 0.5 usually will yield results where the adjustment is quite obvious and should be avoided. If this parameter is too high, you will notice contours with a high contrast to be outlined by an extra dark and an extra light line.
- Edges: This parameter is a threshold that controls which luminance variations are considered to be edges and which are classified as noise. You will need to adjust this parameter if you are working in noisy regions of your picture, e.g. in very dark regions with poor lighting, or if the camera was set to very high sensitivity. If this value is too high, most pixels will qualify as edges and you will emphasize the noise, if this parameter is set to zero, then no pixels will be enhanced.
- Falloff: The edge sharpening is done in three passes at different radii of the filter, and this parameter is a weight determining the influence of the second and third pass. I never saw the need to adjust this parameter. But if you ever notice an excessive "ringing (moiree)" effect around the edges, you should try to change this setting.
Wow, that is some very useful information! Glad I stumbled upon this thread.
Greg, what is it about PSE that's a disaster on the Mac? I'm considering downloading the trial, but haven't gotten around to it yet. Also, are you referring to version 9, or the actual "latest" version of 10 which was just released in the last week or so?
I sold the PSE 9 as it had tremendous problems with eliminating the Bridge storage filing.
I went back to my version 8 that luckily I kept.
If you go to the Adobe web site there are plenty of complaints.
The thread I started is probably the longest.
I am glad to see they have a new version.
Considering that they only recently added 9 that tells me it was a problem
The other issue was that in the past they always had separate versions for PC and MAC.
9 was a single issue for the 2.
I will check out the 10 and see if it is a MAC version also.
Thanks for your info