Monday, November 16, 2009

Sharpen Your Photos For Display

Most of us upload our pictures or print them the way they were captured by our digital cameras. We read and hear of a post-processing technique called "Sharpening" using "USM" (or "UnSharp Mask") and decide it is just too difficult for us. If you are comfortable using a computer and can load an image into an image editing software, such as Photoshop Elements, then be prepared for a pleasant surprise! 

Most cameras -- especially in the "pro" category -- will capture an image without applying any sharpening to it, resulting in an image that appears "soft" or even slightly "out of focus." Others will apply a certain degree of sharpening to the images and output crisp looking images. Most beginners prefer the latter type, while most advanced photographers prefer the former. Here's why.
When a camera processes your images, it is in effect deciding the amount of sharpening to give your images without your input. Some cameras do a good job at it, others do too much of it. It is akin to processing labs a couple of years ago that treated all your negatives the same way, and all got printed with the same adjustments. If you go back and look at your old prints, chances are they all have a bluish tint to them. As competition heated up, processing labs started to examine each print individually and making adjustments and corrections to each, resulting in much better color rendition. This is akin to you sharpening your own images the way you like them.
Of course, if you have to do that for every single picture you take, it is really not worth it. Truth is, most pictures don't need it. It is only the few pictures you really want to highlight, either on screen or in print, that will benefit most from sharpening (and other adjustments).
If your camera produces "soft" images (because it does not sharpen for you), then you are in fact in luck. Using an image editing software such as Photoshop Elements, you can apply sharpening yourself to selected pictures for maximum impact, either for screen display or for printing.
In fact, if you are in the habit of printing unretouched pictures from the different digital cameras and then comparing the prints to see which camera is better, you are making a grave mistake. Unless you have sharpened the images individually first, the comparison is really not a valid one, and you'll end up with wrong conclusions.
Sharpening for screen display and sharpening for prints are also two different things. So, let's understand what sharpening is and how to do it for screen display. (I cover for screen display here, and for prints at a later date.)
What Is Sharpening?
Sharpening is enhancing the edges of an image. This edge enhancement technique is called unsharp masking and involves isolating the edges in an image, amplifying them, and then adding them back into the image. In Photoshop, amplifying the edges is accomplished by locating pixels of greatest contrast, lightening one side and darkening the other. Once sharpening is appropriately applied, people's reactions is usually, "Wow! It jumps right out at you."
Perhaps the simplest way to understand sharpening is to attempt one in Photoshop Elements.
Here is our original unsharpened image we will be working with in this tutorial. It is a "soft" image, even appearing out of focus in some places. Don't be deceived by appearances.

Original unsharpened image
Original unsharpened image
Canon PowerShot S50
Program AE, Center-weighted averaging, Auto WB
7.1mm, 1/60 sec., F2.8, ISO 50, Flash ON

Make A Copy
Open Photoshop Elements and do File - Open - select the picture you want to work with.
Immediately, save it as a different name, with a psd (Photoshop) extension. For example, if your original image was named IMG0001.JPG, then save it as IMG0001.psd (i.e. use the default extension of the image editing software you are using). This way, you will preserve the original file (IMG0001.JPG).
If the Layers Panel is not on your desktop, drag it from the tabs at the top into your work area. If necessary, drag the bottom edge down so you can see more than one layer. You will see your picture (probably named "Background") in a layer.
Double click on that layer and rename it as original. (You could leave it as "Background" but renaming it is a good habit, since you may want to add a real background in some cases.)
Now, drag it to the new layer icon (the middle one at the bottom of the Layers Panel) to create a new layer, original copy.
Click on the original copy layer to select it as the one you want to work with. (Remember, we never want to muck with the original layer.)
Your Layers Panel should end up looking like this:

Sharpen
If not already selected, click the original copy layer to select it.
From the menu bar, select: Filter - Sharpen - Unsharp Mask... and type in Amount = 200%, Radius = 1.2, Threshold = 4. Click on Preview to view the original and sharpened version. Yeah!, I hear you say already. You may select different values, though the above values are a good starting point.
Separate Darken and Lighten Pixels
Now, copy the sharpened original copy layer by dragging it to the new layer icon. You'll end up with original copy 2.
Double click on original copy and rename it darken.
Double click on original copy 2 and rename it lighten.

Select the darken layer by clicking on that layer.
Set the blending mode to darken: See where it says, Normal in a drop down box at the top of the Layers Panel? Click on the down arrow and select "Darken":

Select the lighten layer by clicking on that layer.
Set the blending mode to lighten: Click on the down arrow and select "Lighten":

What we have done is separate the darken and lighten pixels into two layers. Now, we can control each layer separately.
Adjust Sharpness
If you are following this tutorial in your own Photoshop Elements and using our image, you'll notice that the lighten pixels (the highlights) are a bit too bright. (You might have to zoom in 200% to see things clearer.)
Click on the lighten layer to select it and adjust the Opacity until you are satisfied. (Ensure Preview is ON.) In my case, I select 26%.
Likewise, select the darken layer and adjust the Opacity until the darken pixels (the dark edges) just "jump out." I select 90%.
Each picture you sharpen will require different values, so if you are using your own image, adjust to your own liking.
Here is the original (unsharpened) version:
Original unsharpened image
Original unsharpened image
And here is my final (sharpened) result:
Sharpened image
Sharpened image
There, you have it. Pretty simple, huh?
Save this final work (in our example, as IMG0001.psd).
  

http://www.photoxels.com/tutorial_sharpen_display.html

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