"Unsharping" reduces sharpness

[Blazk]

Hello,
As I was doing "Unsharp" to my photos, I've noticed that after I click OK, the sharpness immediately goes down a bit.
The photos are of gemstone Jewelry closeups, for print, taken with Canon PowerShot A10, in High Resolution.
The numbers I use are quite high, since this type of jewelry has many small pieces of beads,chips - so I use Sharpness 180-245, Radius 5-7, Treshold 2.
My previous prints came out very nicely, and I haven't payed attention if the same thing was happening before.
Some came out with not enough contrast(foggy a little), that's why I'm redoing these ones.
Any idea why this happens?
Thanks!

 

[MindBender]

It's nearly impossible to say without seeing the actual photos.

Here are some general things to think about though:

Unsharp increase local pixel contrast to make things appear sharper as their highlights are "stronger" once it has been run.

Any filtering will generally cause some loss of the original detail of the document. Even if things become clearer, we are still changing the original with syntetic methods. What this boils down to is that the same procedure doesn't always work right even if we think it should

Sometimes using a high pass is a better method of "sharpening" than unsharp. Duplicate the layer. Run filter > other > high pass at a pixel or two (just until you start to see lines appearing in the grey, just takes a little practice to predict). Then set your blending mode to something soft like Overlay.

Learning to use the "custom" filter is a major headache, but worth the effort. I'm not a master at this, but I've worked with it a bit. This is one of those black magic type filters that just takes some doing. Anyone else have some good information on "custom"? I don't have a thourough understanding of how the engine works, other than I know that it changes the pixel contrast and (i believe luminocity) based on the matrix input.

Sometimes the problem with your photos isn't "sharpness" but overall cast removal, or color correction. If things aren't looking as sharp as you want, make sure your neutrals are balanced and your histogram looks like what you'd expect it to. Getting a skintone and a greyscale ramp are good guides to help with this.

Hope that helps.

 

[markzebra]

hmm ??your radius is too high? - 5 to 7 seems too high for most work. Unless your dealing with 1200 dpi images.

Oh yeah - and threshold should always be zero

 

[AppleCider]

I agree, it's impossible to see what you mean exactly without seeing the image, but I suspect you may be seeing slight halos, color shifts and artifacts, which make the image look blurry.

One trick to prevent this:

After you fool with the image, but before doing the Unsharp Mask (which should be done as a last step), change the image mode to Lab Color (Image > Adjust > Mode > Lab Color). Don't worry, you can change it back later without any loss of color or quality.

Now go to your Channels Palette (Window >Show Channels if it's not visible). Click on the Lightness channel. You'll be applying Unsharp Mask to the image's luminosity only.

You'll see a greyscale image on screen; that's okay. Now apply the Unsharp Mask filter; fool with the sliders. In general, you can use higher values than you would on an RGB image, but be sure the radius isn't much over 1 pixel.

Now you can change the Mode back to RGB.

 

[AppleCider]

Oh, markzebra, I meant to tell you...I'm mezmerized by your avatar!

 

[Erik]

To get a better contrast, use levels. Hold down Opt/Alt while you drag the left (dark) and right (light) sliders just below the histogram. Your image will turn white, and you will be able to see exactly when you arrive at the darkest/lightest pixels in your image as they will appear on the white. This way, you can enhance the overall contrast. Yet, you loose some intermediate hues as your histogram will be torn apart.

To get the best result: take a new photograph with better contrast. Better that than having to mess with a bad one.

Or if you use traditional slides that yo scan: get scanner software that has levels, curves etc. Like Silverfast.

 

[wbiss]

Welcome to the forum Blazk!

All great "tips" offered up here so I hope that you have found a solution that works for your particular situation!

 

[MindBender]

Or if you use traditional slides that yo scan: get scanner software that has levels, curves etc. Like Silverfast.

Don't forget, also, that scanning at 16bit will give you MANY more levels to work with than scanning at 8bit (64k as opposed to 256). Although, you won't have as many options to edit with (not yet, we'll see how good CS is).

 

[Erik]

There are several things one can do with 16bit files in 7 too, and I suggest keeping it sweet sixteen for as long as possible.

Although I don't really see the difference when printed on my photo desklet with 6 colours. (Simple CMYK won't really change as there are too many factors there, not the least the presses themselves)