Graphics Programs Reference
In-Depth Information
When you're using any filter, you should view your image at actual size to see the results more
clearly.
2
Choose > Filter > Convert for Smart Filters. If a Warning dialog box appears click OK. Your Back-
ground is converted to Layer 0 and is a Smart Object.
3
Choose Filter > Sharpen > Unsharp Mask.
The Unsharp Mask dialog box displays three settings:
Amount
:
The Amount value ranges from 0 to 500. The amount you choose depends upon the subject
matter. For example, you can sharpen a car or appliance at 300 or 400, but with a portrait, every
wrinkle, mole, or hair will become more defined. If you are unsure about the value to use, start with
150 and gradually increase the amount until you find a value that looks good.
Radius
: The Unsharp Mask filter creates a halo around the areas that have enough contrast to be con-
sidered an edge. For print images, you can use a value between 1 and 2, but if you're creating a bill-
board or poster, increase the size.
Threshold
: The Threshold value is the most important one in the Unsharp Mask dialog box because it
determines the parts of the image that should be sharpened. This value can range from 0 to 255. Apply
too much, and no sharpening appears; apply too little, and the image becomes grainy. For example, if
you leave it at zero, noise appears throughout the image, much like the grain you see in high-speed
film. A value of 10 causes the filter to apply when the pixels are ten shades or more away from each
other. Start with a value of 10, and gradually increase it until you find a value that works well.
4
For this exercise, set the Amount to
200
, Radius to
.5
, and Threshold to
10
.
You can compare the original image with the resulting image in the Preview pane of the Unsharp
Mask dialog box by clicking and holding the image in the Preview pane; this shows the original state
of the image. When you release the mouse button, you preview the Unsharp Mask filter again.
5
Click OK to apply the filter. The image is sharpened.
6
Choose File > Save; keep the file open for the next part of this lesson.
In some images, stray colored pixels might appear after you apply the Unsharp Mask filter. If this occurs
in your image, choose the Double-click to edit filter blending options button ( ) to the right of Unsharp
Mask in the Layers panel. In the Blending Mode dialog box, select the Luminosity blend mode from the
Mode drop-down list and then click OK. This step applies the Unsharp Mask filter to the grays in the im-
age only, thereby eliminating sharpening of colored pixels.
Selecting the best image format
When saving an image that you will use on the Web or in other devices, you need to consider two factors:
the quality and size of the image file. When you are saving a file, you must find a balance between the
quality you want and the download speed your viewers demand.
In this section, you will look at different file formats and decide on a format for the picture you just res-
ized. The following example uses the Save for Web feature in Adobe Photoshop.
Choosing the right file format
