Top 5 Photo Problems
Photos are like snowflakes: No two are exactly alike. Nonetheless, we all encounter the same problems with our digital photos, over and over again: red-eye, digital noise, bad exposure, blurry images, and distracting elements. Correcting these problems goes a long way toward improving your digital images dramatically.
In the next few pages, we'll look at the five problems that most frequently plague digital photographers, and how to fix them--as well as how to avoid them in the first place.
Prevent the Dreaded Red-Eye
You'll usually see the red-eye effect in low light, when your subject's eyes naturally dilate to let in as much light as possible. When you fire your camera flash, the light passes through the open pupils and bounces off the back of the eye, which then looks red. That's why you'll never see red-eye in a photo taken outdoors in bright sunlight. To minimize the possibility of red-eye, take your pictures outdoors in daylight, or inside near a window where you have natural lighting. At night, brighten the room by turning on all the lights you can.
If you're stuck in a dimly lit room or if you're outdoors at night, turn to your camera for help. Your camera's red-eye reduction mode (usually identified by an eye-shaped icon) fires the flash several times quickly right before the camera takes the picture, forcing your subject’s pupils to close down to a smaller size. Remember that the picture hasn't been captured at the first sign of flash, so hold the camera steady--and warn your subject to hold still for a few seconds, to be sure that the camera is done taking the photo.
Your camera's red-eye mode can help, but it isn't a cure; you still might end up with red-eye in some photos. When that happens, use the red-eye tool in your favorite photo editor to blot out the red.
Avoid Digital Noise
Digital noise is comparable to the "grain" you sometimes notice in film photography, as you see here in this noisy photo. Not only do noise and film grain look somewhat similar, but they are also caused by similar factors.
Both are accentuated by high ISO levels, for example. ISO is a measure of your camera's sensitivity to light, which you can increase to take photos in low-light situations. You'll always have some noise in your photos, even at your camera's lowest ISO; but the higher you crank the camera's ISO, the more noise that results. Long exposures are also major contributors to noise: The longer the exposure, the hotter your camera sensor gets--and all that heat contributes to digital noise in the final image. It's rarely a problem in daylight, but long exposures at night can fill your photos with noise.
So how do you avoid digital noise? In general, shoot with the lowest ISO possible. You might need to bump up your ISO when you're shooting indoors without a flash, for instance, but don't crank it all the way to ISO 1600 when ISO 800 might do. Just increase the ISO until the shutter speed is fast enough to take a sharp photo, which is usually something like the inverse of the focal length. Here's an example: If the lens is set to 100mm, you can probably get a fairly steady shot with a shutter speed of 1/100 second. Likewise, though longer exposures can lead to extra noise, you can fight back by turning on your camera's built-in noise reduction. Many cameras have an automatic noise reduction feature that kicks in when the shutter speed exceeds 1 second. Check your camera's user guide.
Tricks for Reducing Noise
If you just can't avoid a little noise, you can smooth out your photos with software. Many photo editing programs come with some sort of noise reduction filter. In Adobe Photoshop Elements, for example, you choose Filter, Noise, Reduce Noise from the menu. Just as you have to contend with trade-offs between ISO and noise, though, you have to weigh the trade-off between reducing noise and erasing useful details in the photo.
With Strength set low and Preserve Detail set high, the image is crisp and sharp, but also unattractively grainy. With Strength set high and Preserve Detail set low, the image loses detail and takes on a "soft focus" glow. I've used the Noise filter on the top half of this photo to show how it affects the scene. Notice that the background and the girl's face are dramatically less speckled; her face, however, has been smoothed to the point that a lot of detail has been lost. Another option is to try a stand-alone noise reduction program. I discussed two good choices--Noiseware and Noise Ninja--in "Eliminate Noise From Your Photos."
Correct Bad Exposure With Curves
The Curves tool in many image editors allows you to correct the exposure of your photo by tweaking the brightness and contrast. In fact, you can tweak the shadows, midtones, and highlights of a photo independently. In Photoshop Elements, choose Enhance, Adjust Color, Adjust Color Curves from the menu.
You have two ways to use Photoshop Elements' Curves tool: You can move the sliders for precise control, or you can click a style from the list to adjust the options by a preset amount. To increase the brightness of the shadows in a photo, for example, click Lighten Shadows in the list of styles, or drag the Adjust Shadows slider to the right. You can see the change in the After image in the Adjust Color Curves dialog box and also in the original photo back in Photoshop Elements' canvas.
I recommend that you make changes like this in a layer. That way you can adjust the opacity of the layer to reduce its intensity or even delete the layer entirely and get back the original photo, long after you made the original changes. Working in a layer is easy to do. Before you start editing with the Curves tool, just choose Layer, Duplicate Layer and click OK. Now you have two identical layers. When you choose Enhance, Adjust Color, Adjust Color Curves, the changes you make to the photo will be in the top layer only. For more on handling layers, see "Photo Editing Basics: Working With Layers."
Sharpen Fuzzy Photos Automatically
In a perfect world, all the photos we snap would emerge from the camera perfectly formed, impressively sharp, and ready for display at the Louvre. Of course, in reality most digital cameras take photos that are a tad soft--which is why it's often a good idea to sharpen your images a little before printing or sharing them.
One way to sharpen your photos is to let your camera do it for you. Check out your camera's user guide, and you'll probably find a way to sharpen every photo automatically, as it's taken (as you see in this page from the user guide for our new number-one megazoom, the Canon PowerShot SX20 IS). A built-in sharpening feature is a simple and painless way to give images a little bite, but it isn't perfect. You have no real control over how much sharpening is applied--and worse, the sharpening affects the entire photo.
Use Your Photo Editor's Unsharp Mask
I recommend that you sharpen your photos by hand, using the Unsharp Mask tool in your favorite photo editor. To try it out, first open an image file in your editing application; I'll use Adobe Photoshop Elements here for example, but you can get the same results with almost any program.
Choose Layer, Duplicate Layer and click OK. In the Layers palette on the right side of the screen, click the top layer to make sure it's selected, and then choose Enhance, Unsharp Mask. Select whatever sharpening settings you like best. In general, you'll want to set Amount to between 100 and 200, Radius between 1 and 2, and Threshold between 0 and 10. Higher Amount and Radius values increase the sharpening effect; but the lower the threshold, the stronger the effect. For an overview of how Unsharp Mask works, read "Focus Tips, Moving Pictures Between PCs."
After you apply some sharpening to the top layer, you can vary the opacity until the photo looks right. You can also use the Eraser tool to erase the top layer selectively, letting the unsharpened lower layer peek through; it's a handy technique to sharpen the subject but leave the background softly blurred.
Clone Away Your Problems
You have no doubt taken some photos in which something annoying--a wandering tourist, a telephone pole, a fluttering pigeon--ruins an otherwise wonderful photo. In many cases, it's a snap to clone away unwanted elements in Adobe Photoshop Elements or any other popular photo editing program.
To get started in Photoshop Elements, click the Clone tool in the palette on the left side of the screen (it looks like a rubber stamp). Next, find a region in your image that's similar to the area you want to cover. If you want to airbrush away a power line that runs through the sky, for instance, look for a nearby patch of sky to serve as your source for the clone brush. To set the source, position the mouse pointer over it and Alt-Click. Now move your mouse over to the area you want to brush away, and start painting. Don't try to cover the blemish all at once; paint a little, pick up the mouse, and paint again. This action reduces the chances that a recognizable pattern will appear. You can see a work in progress in this example, where I'm cloning away a boat by painting over it with water.
Advanced Clone Brushery
The Clone tool works best in small areas because you can start to see a repetitive pattern in the photo if you paint over too large a region. But to help you out, the Clone tool has two different modes, which you control via the Aligned checkbox in the toolbar at the top of the Photoshop Elements screen. In one mode, when you pick up the brush and paint elsewhere, the source stays where you put it; this is called Nonaligned mode. If you pick up the brush and start painting elsewhere, and the source moves the same relative distance from where you started, your tool is in the Aligned mode.
It's kind of a complicated concept, but you can see what I mean if you try cloning someone's face and then painting it somewhere else in the photo, as I did here. If you clone it using Aligned mode, you can paint the entire face without any glitches even if you paint a few strokes, lift and move the mouse, then click and paint again. Try that in Nonaligned mode, though, and you'll restart the face from the clone source point wherever you click, making it impossible to paint a face unless you do it in a single set of strokes without lifting your finger off the mouse button. Some pictures work better with one mode or the other--experiment to see which is best in each situation.
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