The following tips, excerpted from Deke McClelland's Real World Digital Photography by Peachpit Press, will help you learn how to master a few of Photoshop's capabilities. These tips will also work in Photoshop LE. Adjust Focus Sharpening and other focus adjustments are all about modifying edges. In Photoshop, when you think edges, you should think filters. Unsharp Mask enhances the contrast of pixels along edges, thus creating the appearance of sharper focus. Unsharp Mask Quite simply, Unsharp Mask is the only sharpening command you'll ever need. When you choose Filter, then Unsharp Mask, Photoshop presents you with three option boxes that let you control how the sharpening is applied-- Amount, Radius, and Threshold. The first two are far and away the most important. Amount: Vary the Amount value from 1 to 500 percent. Larger values result in more sharpening. Radius: The Radius value controls the thickness of the sharpened edges. If you want thin, crisp edges, use a low value such as 0.5. If you want thick edges, try a value of 1.0 or higher. Values of 3.0 or higher are generally reserved for special effects. Higher resolutions require higher Radius values. As a rule of thumb, use 1.0 pixel of Radius for every 150 ppi of image resolution. Threshold: This value tells Photoshop how different two neighboring pixels must be to be considered an edge. By raising the Threshold value, you tell Photoshop to sharpen some edges and leave others untouched. When Threshold is set to its default value of 0, the Unsharp Mask filter sharpens all pixels evenly. Color Adjustments The most common problems associated with digital photographs are brightness and contrast. The contrast is often too low, giving the photograph an ashen or muddy appearance. Meanwhile, the brightness is more often than not too dark, resulting in lackluster highlights and obscure details in the shadows. When you add the element of color, correcting an image becomes more complicated. You have to consider not only brightness and contrast, but quality of color. Luckily, Photoshop provides a wealth of commands to fix color cast, saturation, and the occasional color mismatch. Variations Photoshop's most straightforward color correction feature is Image, Adjust, Variations. The Variations window includes postage stamp-sized thumbnails to show you how an image will look when subjected to different color adjustments. Just click on the thumbnail that looks better than the current state of the image. Each correction thumbnail appears opposite its color complement, so More Blue removes a yellow cast, More Cyan removes a red cast, and so on. The Variations dialog box lets you modify the colors of highlights, midtones, or shadows independently. You can likewise adjust the intensity of a single click using the Fine/Coarse slider. If you went a little overboard with the correction-- the most common outcome-- you can back off the effect by choosing Filter, then Fade Variations. Lower the Opacity value to mix the corrected image with the original one. Saturation The Variations dialog box also offers the Saturation option, which replaces the color cast and brightness thumbnails with two adjustment options, Less Saturation and More Saturation, with Saturation being used as merely another word for the intensity of a color. Highly saturated colors are vivid and garish. As you lower the saturation, the colors tend toward gray. To drain any excessive brilliance in your image, select Saturation at the top of the Variations window and click one or more times on the Less Saturation button. Changing a specific color The Hue/Saturation command is useful for selectively altering colors in an image. For example, suppose you want to change a blueberry iMac to grape. Open the Hue/Saturation dialog box and choose Blues from the Edit pop-up menu. This limits the modifications to just the blue pixels in the image. To make sure that the correct blues are selected, move the cursor outside the dialog box and click in the area that you want to modify. Photoshop automatically selects the proper color spectrum. Next, edit the Hue and Saturation values until the colors look the way you want. To make the blue iMac purple, I changed the Hue value to +18 degrees, which rotates the colors around the color wheel. I also decreased the Saturation value by 40 percent, to better match the translucent violet of the grape iMac. (Instead of entering numerical values, you can use the sliders to adjust the values.) The only caveat is that Hue/Saturation changes all of the pixels of a certain color in an image. So if something other than the iMac were colored blue, you would have to select the region you wanted to modify before choosing Hue/Saturation. Deke McClelland is the author of the award-winning Photoshop Studio Secrets, 2nd Edition (IDG Books) and Real World Digital Photography (Peachpit Press).
Adjust Focus
Sharpening and other focus adjustments are all about modifying edges. In Photoshop, when you think edges, you should think filters. Unsharp Mask enhances the contrast of pixels along edges, thus creating the appearance of sharper focus.
Unsharp Mask
Quite simply, Unsharp Mask is the only sharpening command you'll ever need.
When you choose Filter, then Unsharp Mask, Photoshop presents you with three option boxes that let you control how the sharpening is applied-- Amount, Radius, and Threshold. The first two are far and away the most important.
Amount: Vary the Amount value from 1 to 500 percent. Larger values result in more sharpening.
Radius: The Radius value controls the thickness of the sharpened edges. If you want thin, crisp edges, use a low value such as 0.5. If you want thick edges, try a value of 1.0 or higher. Values of 3.0 or higher are generally reserved for special effects.
Higher resolutions require higher Radius values. As a rule of thumb, use 1.0 pixel of Radius for every 150 ppi of image resolution.
Threshold: This value tells Photoshop how different two neighboring pixels must be to be considered an edge. By raising the Threshold value, you tell Photoshop to sharpen some edges and leave others untouched. When Threshold is set to its default value of 0, the Unsharp Mask filter sharpens all pixels evenly.
Color Adjustments
The most common problems associated with digital photographs are brightness and contrast. The contrast is often too low, giving the photograph an ashen or muddy appearance. Meanwhile, the brightness is more often than not too dark, resulting in lackluster highlights and obscure details in the shadows.
When you add the element of color, correcting an image becomes more complicated. You have to consider not only brightness and contrast, but quality of color. Luckily, Photoshop provides a wealth of commands to fix color cast, saturation, and the occasional color mismatch.
Variations
Photoshop's most straightforward color correction feature is Image, Adjust, Variations. The Variations window includes postage stamp-sized thumbnails to show you how an image will look when subjected to different color adjustments. Just click on the thumbnail that looks better than the current state of the image.
Each correction thumbnail appears opposite its color complement, so More Blue removes a yellow cast, More Cyan removes a red cast, and so on.
The Variations dialog box lets you modify the colors of highlights, midtones, or shadows independently. You can likewise adjust the intensity of a single click using the Fine/Coarse slider.
If you went a little overboard with the correction-- the most common outcome-- you can back off the effect by choosing Filter, then Fade Variations. Lower the Opacity value to mix the corrected image with the original one.
Saturation
The Variations dialog box also offers the Saturation option, which replaces the color cast and brightness thumbnails with two adjustment options, Less Saturation and More Saturation, with Saturation being used as merely another word for the intensity of a color. Highly saturated colors are vivid and garish. As you lower the saturation, the colors tend toward gray.
To drain any excessive brilliance in your image, select Saturation at the top of the Variations window and click one or more times on the Less Saturation button.
Changing a specific color
The Hue/Saturation command is useful for selectively altering colors in an image. For example, suppose you want to change a blueberry iMac to grape. Open the Hue/Saturation dialog box and choose Blues from the Edit pop-up menu. This limits the modifications to just the blue pixels in the image. To make sure that the correct blues are selected, move the cursor outside the dialog box and click in the area that you want to modify. Photoshop automatically selects the proper color spectrum.
Next, edit the Hue and Saturation values until the colors look the way you want. To make the blue iMac purple, I changed the Hue value to +18 degrees, which rotates the colors around the color wheel. I also decreased the Saturation value by 40 percent, to better match the translucent violet of the grape iMac. (Instead of entering numerical values, you can use the sliders to adjust the values.)
The only caveat is that Hue/Saturation changes all of the pixels of a certain color in an image. So if something other than the iMac were colored blue, you would have to select the region you wanted to modify before choosing Hue/Saturation.
Deke McClelland is the author of the award-winning Photoshop Studio Secrets, 2nd Edition (IDG Books) and Real World Digital Photography (Peachpit Press).
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