Please read this ..... - Perfectly Captured Gallery

Please view the large image.
I'm posting this because my previous explanation of how to use the high pass filter and subsequent posts by Rob (shimshams) has become muddied and given members completely the wrong idea with the result that their pictures are over-sharpened and others have been disappointed with results.
My previous explanation stands but the figures given are for the web image I downloaded from PC. I have been using this method for 12-15 years and I was taught by a Photoshop professional so I can assure you my default figures are correct. Anything that requires more than 0.5 pixels is only worthy of the bin.
It is worthwhile going through the whole sharpen process so I'll assume you are working on a full resolution (300ppi), image with the idea of posting to the web.
If I use Photoshop or Elements I would begin with my default USM (unsharp mask), settings of Threshold 0, radius 1, strength 150. These may differ a little according to camera make and model but they will not be far off - if they are then your picture is probably inherently soft through mis-focus, or camera/subject movement and should go in the bin..
Complete all pp, then size your image at 72ppi (important) then enter whatever size you want up to 1600pixels (perfectly captured max size). 72 pixels is the native resolution of your screen/monitor and is also the best res to see the effects of the HPF. You must also view the image at "actual pixels".
Now go to layers>duplicate layer and ok the box that appears. Next go to Filters>other>high pass filter. Your image will go gray and a dialogue box appears. Enter (as default if your previous sharpen was good), a radius of 0.3 pixels - (yes, 1/3rd of a pixel which shows how fine this adjustment is). Ok it. In later versions of PS and elements the layers palette is open by default but if not, - go up to window>layers. In the palette you will see the word "normal". Click and from the drop down of blend modes choose overlay (more or less by default). Your image is back. Next to the layer in the palette you'll see an eye icon. Click this on and off to see before and after - don't forget to leave it on! While here click on overlay and try "vivid" and "hard light". The most useful modes for us here are overlay and vivid the last needs to be used with care, watch for jaggies on straight lines and take care with leafy, grassy scenes. Soft light can used for fur, feather and babies. If Vivid or stronger is used then I mostly reduce opacity by 50% by slider (click on opacity) or entering a figure. as you can see, this method is almost infinitely adjustable. Finish with (say) overlay. If you want more sharpness without using (say Vivid) go to edit undo back to where you enter the figure and try 0.4 pixels. You shouldn't really need more than 0.5.
When finished go to layer>flatten layer. If necessary change the colour profile (edit>convert to profile and choose sRGB IEC 1966-2.1) this will appear by default from now on so you won't have so much to choose from. Compress for the web by your usual method. After your first use of HPF it will appear at the top of your filters list as last used filter and if the 0.3 applies you just click that option and the grey image appears already at 0.3 so you jump to the blend modes.
The HPF may be used (but with a little more difficulty) in PS on full res images but with much higher figures.
I hope this has cleared up any confusion and encourage you to use this method for sharper more refined images. My email is vjchapman@btopenworld Drop me a line if you need further explanation or need talking through it on Yahoo voice. After 2/3 uses you will find it easy and second nature and will not use anything else.