- Basic Image Adjustments
- Improving Color and Lighting with Picasa
- Sharpening and Applying Special Effects
- Sharpening with Picasa: How Much Is Enough?
This chapter is from the book
This chapter is from the book
This chapter is from the book
Improving Color and Lighting with Picasa
If your camera is working properly and if your printer is working properly, you probably don’t need to make any color or lighting adjustments in Picasa (or other photo management software). However, there may be times when you need to work on the basic appearance of your photos. When those situations arise, Picasa offers a couple of ways to fix things: the automatic way and the "in control" way.
Picasa’s Automated Color and Lighting Repairs
Picasa’s Basic Fixes tab offers three buttons and one slider to help you improve the color and lighting in your photos (see Figure 3.11).
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Figure 3.11 Double-clicking a photo in the Library opens the Basic Fixes tab.
Here’s what each of the four features does for your photo:
I’m Feeling Lucky—When you click the I’m Feeling Lucky button, Picasa analyzes and adjusts your image, deciding what should be "black" and "white" and trying to determine whether the image needs a color adjustment. It never hurts to click this button; you can always reverse the procedure if you don’t like the result by clicking the Undo button.
Auto Contrast—When you click Auto Contrast, Picasa finds the darkest part of your image and makes sure that it’s black, then finds the lightest area and makes it white. The rest of the image is then spread evenly between black and white. Auto Contrast can give your photos a little "pop" to up their appearance. Compare the "before" and "after" Auto Contrast shots in Figure 3.12.
Auto Color—If your photo has a general color cast—that is, an unwanted tilt toward orange or blue—the Auto Color button might be able to help. In Figure 3.13, you see that Auto Color has done a fairly decent job of eliminating the too-orange look of the holiday lights, neutralizing the color of the surrounding ice.
Fill Light—If your image is generally dark, or at least darker than you want it to be, you can use the Fill Light slider to brighten things up. As you see in Figure 3.14, this adjustment does a very good job.
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Figure 3.12 On the left, the original image. On the right, the result after clicking Auto Contrast.
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Figure 3.13 Picasa’s Auto Color feature neutralizes the color of a photo.
Remember that you can use Picasa’s automated adjustment features in combination. In Figure 3.15, you see the result of using Auto Contrast, Auto Color, and the Fill Light slider. Compare this version with the image on the left (the original) in Figure 3.14.
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Figure 3.14 You can use the Fill Light slider to produce an overall brighter picture.
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Figure 3.15 You can use the auto adjustments together to improve a photo.
Picasa’s Advanced Color and Lighting Capabilities
While the automated adjustments in Picasa’s Basic Fixes tab do a reasonable job on many photos that require some improvement, the Tuning tab holds the key to control over your images. Not only can you use the Tuning tab to improve the general appearance of an image, but you can use it to create dramatic lighting effects, such as that shown in Figure 3.16.
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Figure 3.16 Darkening the shadows and lightening the highlights lets the subject of the image stand out from it surroundings. (The original is shown to the right.)
Here’s a look at the various controls in Picasa’s Tuning tab:
Fill Light—Just as in the Basic Fixes tab, the Fill Light slider in the Tuning tab enables you to generally lighten an image.
Highlights—You use the Highlights slider to brighten the lighter areas of an image.
Shadows—The Shadows slider lets you darken an image’s shadows.
Color Temperature—You use the Color Temperature slider to remove a color cast from an image. You drag to the left to make the image less orange and to the right to make the image less blue.
Neutral Color Picker—You can click the eyedropper icon to select the Neutral Color Picker tool, and then you can click once in your image on something that should be light gray (not something that is gray, but something that should be gray). Picasa automatically balances the color in the image to remove a color cast. (This is an automated way of correcting a color cast instead of using the Color Temperature slider.)
One-click fix for lighting—You can click the button to the right of the Highlights slider to have Picasa automatically adjust the lighting in a photo.
One-click fix for color—You can click the button to the right of the Neutral Color Picker to have Picasa automatically adjust the color in a photo.
What Is a Histogram?
Picasa (and many other programs) can show you a graph that displays a mathematical representation of the appearance of an image. This graph, called a histogram, shows the distribution of pixels (the little squares of color of which a digital photo is created) at various brightness levels. The histogram displays the tonality (lightness, brightness/darkness) of your image.
In Picasa, you can show/hide the histogram (and camera info) with the propeller beanie button to the lower-right of the preview area:
So when should you use the histogram? When working in the Tuning tab, you might want to keep an eye on the histogram for three things:
Loss of detail in the highlights—As you drag the Fill Light or Highlights slider, it may look like the histogram is disappearing off the right edge of the graph. That indicates that you’re losing detail in the image’s highlights—too many pixels are becoming pure white.
Loss of detail in the shadows—While adjusting the Shadows slider, you might see the histogram disappearing off to the left. That indicates that you are losing detail in the shadows of your image as too many pixels are forced to pure black. (That’s not always bad—take another look at Figure 3.16.)
Posterization—As you drag the Temperature slider, watch for gaps developing in the histogram:
This shows posterization—pixels of similar color being forced to a single color. Posterization changes smooth, gradual changes in color into blocky bands of different color. It’s often most evident in highlights and shadows in a photo.