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Last Updated:
Jan 20th, 2007 - 12:55:03 |
What makes USM a difficult tool to use, is the fact that the results are subjective. There are no exact parameters that will work for every image or even every type of image. In addition the viewer has a role in determining what is acceptable sharpening to their preference and including variables such as the distance the print is viewed at and even their vision strength. As a general rule, photography is supposed to be judged at arms length and you should sharpen your images accordingly however this may not always be the case and sharpening should not only be applied at the very last step of editing but also only once you have determined the use the photograph will be put to. Therefore sharpening should be applied before ouput and not necessarily as a standard addition to the image at the end point of editing. Prints need to be slightly oversharpened to compensate for the loss of sharpness inherent in ink jet printing, while photos destined for web viewing need less sharpening as the compression for web display will exaggerate the effect.
USM can be used globally or by using the selection tools, be applied only to a specific area. Certain areas of an image such as eyes often need more sharpening than others for visual impact.
After all editing (color, cloning etc) has been completed, save the image as an original. Open a duplicate to apply the sharpening too. Distinguish it from the original by adding sharp_print or sharp_web as appropriate. Make sure all layers are flattened.
Launch the Unsharp Tool
Filter> Sharpen> Unsharp Mask
Controlling USM
Radius controls how wide the edges rim becomes. Higher radials cause what is known as halos which are to be avoided. As a general guideline Radius settings are best between 0.6 and 2.0. This setting effectively doubles the edge rim and while high resolution images can withstand a higher radius, care must be taken with photos with fine detail to ensure the detail is not lost in the radius. Portraits tolerate the least amount of radius as it will exaggerate skin imperfections, still life subjects and landscapes tend to tolerate a radius at the higher end of the scale. Areas of noise will also be exaggerated with a higher radius.
Threshold tells PS where the edges of areas of light and dark are. Low values such as 0-2 sharpen more of the areas meaning that everything gets sharpened. Values of 5 or higher exclude larger areas and are generally best for portraits as it helps to exclude areas such as skin. Starting with a threshold of 3-4 will allow you to better decide if more or less areas of the image require sharpening.
Amount controls the emphasis of the Radius and Threshold, exaggerating the edge differences by contrast. The larger the Amount the more obvious the sharpening becomes as it increases the contrast between light and dark pixels. As a general midlevel, a value between 80 and 120 is a starting point. You are more likely to need to increase the Amount than decrease it. However Radius and Amount interact in such a way that reducing one allows more of the other.
In summary as a place to start from for most images:
Radius: Values of 0.6 – 2.0 . Main task is to avoid halos.
Threshold: 1-5+ determined by the image subject
Amount: 80-120 and increase to exaggerate sharpening.
CS2 SMART SHARPEN
Smart Sharpen has been introduced in CS2. It is very similar to the USM but offers more control over specific areas and specific types of blur. As with USM you should view the preview at 100% to best judge the changes you are making. You can click on and off the preview to toggle the before and after view.
The first step is to save the default settings – this way you can choose to start from neutral values. The default settings when you first launch the Smart Sharpen Tool are as shown below:
 
Use the Save setting icon to save the default.
You should also decide at the outset if you will use the More Accurate option during your adjustment process. While it can help create better results is requires a large amount of processing memory and can significantly slow the rendering as you work. You can opt to apply More Accurate after you have made your own adjustments and then choose to apply it and make further changes, if its calculations improve on your own editing. The More Accurate option has the most effect on motion and lens blur corrections.
The default basic menu gives you the options of Amount and Radius. Choosing the values of these is the same as the process in using the USM.
The Remove menu allows you to choose the type of blur that you are trying to reduce. If you can identify the type of blur affecting your image then you can improve the appearance of your image by selecting the type and direction of the blur. This won’t completely rescue out of focus shots and has best results on those photographs where the blur evenly affects the entire image rather than a select area. For best results the degree of blur needs to be less than 5 pixels to still produce competition worthy results. As a general guideline, the radius will need to be at least equal to the degree of blur and possibly double depending on the image subject.
Gaussian Blur is the same type of blur USM uses to apply sharpening so this option is for standard sharpening tasks. Adjust the Radius and Amount along the same guidelines used for Unsharp Mask, however select the Amount that works best for the midtones of the image. You will notice Threshold is missing, select the Advanced radio button to reveal Shadow and Highlight tabs.
Switching to either tab allows you to control the amount of sharpening in those areas.
The Fade Amount will lessen the sharpening effect.
Decrease the Tonal Width to affect only the lightest highlights or the darkest shadows. Increasing the tonal width will affect a greater range of lightness or darkness.
The Radius slider controls which areas are considered to be shadows or highlights. Increase the slider to affect larger areas of dark or light pixels as determined by the tonal width.
 
The ability to decrease sharpening in areas provides more control than the Threshold slider in the USM.
In summary, as a general guideline for using Smart Sharpen:
Select or deselect More Accurate
Determine and select the type of blur. For standard sharpening select Gaussian. For Motion or Lens blur indicate the angle of the blur.
Choose a Radius,
Select an Amount that is best for the midtones in the image.
Make adjustments to improve the sharpening effect in the Shadow and Highlights area if required.
Smart Sharpen has some significant advantages over the USM that should be considered. Smart Sharpen offers more control over tonal range, the edge detection in Smart Sharpen produces less halos and it’s possible to control halos in areas where they are more evident without sacrificing the sharpening in others, the ability to target types of blur and the ability to save and load settings assists with workflow.
© Copyright 2003-2005 by Scrapbook-Bytes; & original creator/s of tutorials/articles
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