Edge/Surface Masking for Sharpening/NR

[bestremera]

Help,

I want to apply the techniques of sharpening only the edges of my image.

I know exactly how to 'find edges' etc. in CS2 and invert the mask to create the edge mask.

I would use the original, non-inverted mask to create a surface mask which I will use to apply Noise Ninja and take the noise out of only the expanses of mostly smooth areas of the image.

But I don't know the actual steps to apply the sharpening and noise removal to the image using the masks.

Any help out there?
Bob

[philbach]

CLICK HERE
Edge Sharpening
Portrait and nature photographers have one thing in common: we hate seeing sharpening artifacts on large blocks of color. Any underlying noise in the image tends to bubble up to visible, and skies or skin tones with too much detail in them don't look as good as gently gradated ones. And if you know what bokeh is (the character of out-of-focus areas) and care about it, you'll be particularly bothered by what happens to noise in out-of-focus areas. Indeed, the first thing I look at in an image to see if sharpening is detectable is the non-detailed, out-of-focus areas. I've seen all kinds of techniques that attempt to deal with the problem of pulling up sharpening artifacts (deselecting the continuous tone areas before sharpening, using history brushes to paint out sharpening in certain areas, etc.). But the following technique is my favorite. Essentially, you build a mask of just the edges in your image, then apply sharpening to the areas under the mask. Here's one set of steps you can use in Photoshop:
1. Open your image, as usual. Perform all your other corrections on it before sharpening, as usual.
2. When you're ready to sharpen, click on the Channels palette and create a new channel. This new channel will eventually be your mask. Change it's name to "Sharpening Mask."
3. Click on the RGB channel for your image.
4. Select the entire image (Select->Select All).
5. Copy the entire image (Edit->Copy).
6. Click on the Sharpening Mask channel you created in Step #2. Paste the image in (Edit->Paste). It'll appear in black and white, but that's what we want, so don't worry.
7. Use the Find Edges filter (Filter->Stylize->Find Edges) on the Sharpening Mask channel. It'll turn into something that looks a bit like a line drawing. Our next steps will be to tweak this mask.
8. We want the black to be really black and the white to be really white in our mask, so use Levels to make the adjustment (Image->Adjust->Levels). Move the black point in from the left, and the white point in from the right (the triangles under the histogram). How much you do this is one of the critical choices you'll be making, so take your time, and remember that the black areas are what are going to be sharpened (the white areas won't be sharpened).
9. We want to hide the actual sharpening of the edges, so we need to make sure there's a smooth transition from white to black in our mask. To accomplish this, use a small Gaussian blur on the image (say 2-4 pixels) (Filter->Blur->Gaussian Blur).
10. Now we need to tell Photoshop that our Sharpening Mask is just that, a mask. To do that, we need to select the black bits only. Use Select->Load Selection. In the dialog that comes up, make sure that Sharpening Mask appears as the Channel and that the Invert box is checked.
11. Click on the Layers tab and make the image visible again. You should see the selection created in Step #10 superimposed over the image.
12. Get the image ready for sharpening. Choose View->Show->Hide Edges (Cmd/Ctrl-H) to make the selection invisible, then choose View->Actual Pixels and scroll the image to an area with which you want to evaluate the sharpening.
13. Finally, we're ready to sharpen. Select Filter->Sharpen->Unsharp Mask and play with the values. Note that you can use much higher amounts than usual, as the halos tend to fall outside the selected areas. Radius should be a low value (.5 to 1.0), and Threshold should be 0. If you find that the sharpened area is too restrictive, go back to Step 8 and change your mask.
Yes, that's a lot of steps, but you can easily make them into a Photoshop Action (make sure to click on the icon to make Steps 8 and 13 editable during playback). This, by the way, isn't the only way to perform an edge sharpening technique. I've seen at least a half dozen variants on the idea of making a mask for the details, then sharpen only at the mask.

[CJ Swartz]

Philbach,

Thank you for a clear explanation and listing of steps for edge sharpening. I did a search in RetouchPro and didn't find a tutorial listed for this important process, and didn't find another thread with the information.

Now, would you like to upload it to the tutorial section?

[philbach]

CJ. I just copied that info off the web site and have never used the technique I posted, so I don't think I should be the one to make a tutorial about it. But thanks.

Phil

[CJ Swartz]

Phil,

Well, I just used it on an image, and your steps were easy to follow and the process worked. I can remember looking at edge sharpening filters for sale a few years ago, knowing that I should be able to do it myself but not sure just how to put it together. I've probably read it on websites elsewhere also, but I didn't remember the process and now we have it here -- forever.... or at least until the next website software change.

[Cameraken]

Nice find Phil

Some prefer to use the Glowing Edges filter instead of find edges as it allows a little more control.

Mitch has some nice ‘Roll your own’ Edge and Surface Actions
Search here for RP member gmitchel or take a look at his website
luminous-landscape.com

Another way to get the mask from a layer into the mask is to use Apply Image

Dupe the background twice
Switch Off the top layer
Run find (or glowing) edges on the middle layer
Switch On the top layer and add a Layer mask
On the Layer mask Apply Image using the find edges layer (blending mode normal Inverted
Switch Off the middle Layer
Sharpen the top layer

Here is one I made earlier
http://www.filterforge.com/filters/1009.html

It does everything for you. Very quick to use

Ken.

[bestremera]

Thanks Everybody,

I'm off to a great start.
Can't wait to try these techniques for my work.

Thanks again,
Bob