Tài liệu Photoshop cs5 by Dayley part 32 doc

Adjusting the White Balance Your camera has a White Balance setting that tells it what lighting is being used when a photo is captured.. If your photo is a raw image, you don’t have to w

You can select more than one image at once by using the Shift key to select images in sequence or the Ctrl/Ô key to select images one at a time You also can click Select All to select all the images

in the filmstrip

To Synchronize which changes are made to all the selected images, click Synchronize This opens the Synchronize dialog box, shown in Figure 8.5 Use the drop-down menu or individual check marks to select which options change across all the selected photos in Camera Raw

FIGURE 8.5

Use the Synchronize menu to choose which changes will be universally made

After you are finished making batch changes, you can select your photos one at time to preview the changes and tweak them individually, but the bulk of the adjustments already are made, saving you lots of time in processing your files

Adjusting the White Balance

Your camera has a White Balance setting that tells it what lighting is being used when a photo is captured A fluorescent light leaves a greenish-yellow cast on your photos, giving your whites a greenish-yellow tinge, for example Your camera can compensate by adjusting the color information

to filter out the color cast But just as any automatic process, the camera compensation is not ideal for all images

If your photo is a raw image, you don’t have to worry if the White Balance setting on your camera

is correct or if it compensated correctly for a particular lighting situation You can adjust the white balance after the photo has been shot using Camera Raw Not that you want to shoot all your images in tungsten mode, but you could

Getting the white balance correct is the single most important thing you can do to improve the col-ors in your photo Even photos that look good can be improved with a simple white balance adjustment, and photos taken in horrible lighting situations make a dramatic improvement The before photo in Figure 8.6 shows an image taken under indoor lighting without a flash It’s hard to tell in the grayscale version printed here, but you can see a color version in the center insert You’ll see that it has very yellow color cast It’s actually hard to distinguish any other color in the photo

The after photo shows the same image after a simple White Balance adjustment The colors have reappeared, the carpet and the cat’s eyes are blue, and his fur is white

FIGURE 8.6

With a click of the White Balance tool, this photo goes from scary yellow to beautiful color

On the Web Site

Find the before image saved as Figure 8-6 on the Web site Can you fix the colors? n

In Camera Raw, you can reset the white balance correctly You can accomplish this in three different ways:

l Change the lighting settings

Using the White Balance tool

The White Balance tool can be an effective way to quickly correct the color of your photo, or it could be an effort in frustration It all depends on the photo you are trying to correct and the area

on which you use the tool The White Balance tool can be found in the tool menu at the top of the Camera Raw dialog box

To use the White Balance tool, select it and click an area of your photo that should be white or a neutral gray, as shown in Figure 8.7 Camera Raw automatically adjusts the colors in your photo to correct the white balance based on your selection Picking just the right color in your photo can be

an effort in frustration It’s not always easy to determine an area that is white or neutral gray If you’re not satisfied with the results, just continue to click different areas and the white balance is set anew each time

FIGURE 8.7

Use the White Balance tool to select a white or neutral gray area of your photo

If you choose an area that is too bright for the White Balance tool to sample, you hear a ping and

no change takes place If you do it a second time, a dialog box pops up, letting you know that the area you are selecting is too bright to be sampled

Changing the lighting settings

You can use the White Balance menu shown in Figure 8.8 to change the lighting settings based on the lighting where your photo was taken If you took a photo on a cloudy day and it turned out too cool, choose Cloudy to warm it up If you took a photo under fluorescent lighting and your photo has that nasty yellow cast, choose Fluorescent to filter it out You get the idea You can pre-view different options before you decide The lighting you took the photo in may not always be the best lighting setting

FIGURE 8.8

You can use the White Balance menu to choose a lighting setting similar to the White Balance setting on

your camera

Needless to say, you probably won’t get the best white balance by using a setting from this menu

After all, it’s still a formulaic adjustment, but it can give you a sample of several different settings

You also can choose the best option from the drop-down menu and then use the Temperature and Tint sliders to tweak the colors until they are just right

Note

It’s not too hard to change the white balance settings so you like the colors in your image If you ever want to

start over from the camera settings, however, choose As Shot from the lighting settings menu n

Using the Temperature and Tint sliders

If you prefer to “eyeball” the changes to your white balance, you can adjust the Temperature and Tint sliders in the Basic panel, as shown in Figure 8.9 The Temperature slider adjusts the levels of yellow and blue in your photo, and the Tint slider adjusts the levels of red and green A good rule

of thumb is to find an object in your photo that you want to be a certain color (skin tones or whites are fairly easy to determine) and tweak the sliders until you have just the color you want

The Temperature and Tint sliders also are ideal for tweaking after you’ve made a white balance adjustment using the White Balance tool or the White Balance menu I usually try the tool first and

FIGURE 8.9

Use the Temperature and Tint sliders to eyeball the white balance of your image

Tip

Add a neutral color card to your shot, and you can set your white balance easily by clicking the card in your

photo after bringing it into the Camera Raw dialog box A light gray piece of paper works really well After

you’ve used it to set your white balance, simply crop it out of the photo If you are taking several photos in the

same lighting conditions, you can remove the card after the first shot and set the white balance for all the

photos at once n

Adjusting Lighting

The next six settings in the Basic panel adjust the exposure and lighting of your photo in different ways This is where you’ll really see a difference in the quality of a camera raw image over a JPEG

Look at Figure 8.10, for example The before photo is a shot of balloons taken in the early morning light, creating a dark photo where the balloons are just silhouettes on the background of the east-ern sky If this image were a JPEG, making the image lighter would result in a grainy photo with lots of color noise The after image in Figure 8.10 shows that fixing this image in Camera Raw turned out with a better result; some noise was created, but not nearly as much as if this image had been a JPEG

FIGURE 8.10

Changing the exposure on a dark camera raw image created much less noise than if the image had been

a JPEG

On the Web Site

Find the before image saved as Figure 8-10 on the Web site Can you fix the exposure? n

Note

Two highlighted buttons at the top of the light and color adjustments found in the Basic panel are labeled Auto

and Default To see the settings that Camera Raw thinks are best for your image, click Auto and the settings are

adjusted to a mathematical interpretation of where the colors and tonal ranges really belong in your image

Auto usually does a good job of setting your Recovery because Recovery is based entirely on the number of

blown out pixels that can be recovered in your image It is only a guess for most of your other settings,

how-ever, and you probably want to do some tweaking.

The Default link resets your image to the settings that it opened with, whether these are the original camera

raw settings created by your camera or settings you created on a previous opening of your image n

As you change the light settings of your image, keep an eye on your specular highlights and deep shadows As you increase and decrease your exposure, you run the risk of creating areas where the pixel information is lost because they are too light or too dark Be sure to keep these areas manage-able Click the Highlight clipping warning and Shadow clipping warning icons in the Histogram, shown in Figure 8.11, to show clipped highlights in red and clipped shadow in blue

Tip

Holding down the Alt/Option key while adjusting the Exposure and Recovery shows you clipped highlights in

your image White areas have no color detail, and red and yellow areas are clipped in one or two channels

Holding down the Alt/Option key while adjusting the Blacks shows clipped Shadows in black n

You also create some noise as you use these sliders The noise is more visible the more the sliders are adjusted You can reduce some noise in the Detail tab, but noise reduction is never an ideal fix

if noise can be prevented in the first place

Change the lighting of your image by using the following sliders in the Camera Raw dialog box:

l Exposure: This slider adjusts the lightness or darkness of your image The results are

sim-ilar to changing the aperture setting on your camera In fact, the numbers on the exposure slider are in increments that correlate to f-stops; 1.0 is similar to widening your aperture one f-stop and so on

l Recovery: The Recovery slider attempts to recover detail from highlights Rather than

darkening the entire image, this slider looks for color detail in the extreme highlights of your image and brings them back into play in an effort to recover any blown out areas of your image You often will want to use Recovery in conjunction with other settings, such

as Exposure and Fill Light so you can achieve a good balance of lighting in your photo

l Fill Light: Adjusting the Fill Light does the opposite of Recovery, lightening the shadows

in the photo This slider is a real miracle worker when either the foreground or the back-ground of your photo is much darker than the other Consider Figure 8.12, for instance

FIGURE 8.11

Use the clipping warnings to show you areas that have lost all color information

Shadow clipping warning

Highlight clipping warning

Indicates clipped highlights

FIGURE 8.12

Adding fill light makes the foreground of this photo much lighter without brightening the rest of the photo

On the Web Site

Find the before image saved as Figure 8-12 on the Web site Can you bring the foreground into the light? n

l Blacks: This setting determines the color values that are mapped to black in a photo

Raising this setting affects the shadows in a photo and creates the illusion of increasing contrast

l Brightness: Although this slider adjusts the brightness of your photo in much the same

way as the Exposure slider, there is one significant difference The Exposure setting increases the lightness or darkness of the entire image, creating the possibility of clipping highlights or shadows The Brightness setting compresses the shadows and highlights as the slider is moved so there is no possibility of clipping This warps the color data in the image, reducing the contrast The Brightness slider should be used after the highlight clip-ping value is set by the Exposure and the shadow clipclip-ping value is set by the Blacks

l Contrast: Contrast is the last tonal adjustment, and it’s the last one you should use As

you raise the contrast in your image, you see the histogram widen The contrast affects the midtones in your image, making the dark midtones even darker and the light midtones lighter

The amazing thing about using Camera Raw to adjust your exposure is that you can create two amazing images with the same shot Consider the balloons again By reducing the exposure and fill light and increasing the blacks, I can change the focus of the image from the balloons to the sky, as shown in Figure 8.13

FIGURE 8.13

Camera raw files can be adjusted to create different looks with the same photo

Adjusting Color and Clarity

Adjusting the color of a raw image can be done in the Basic panel for a general fix, the Tone Curve panel for a targeted fix, and the HSL panel for a highly precise adjustment that allows you to make custom decisions about your color in eight different color ranges Don’t be overwhelmed with all this ability for changing and adjusting the color of your images As with most areas (in life as well

as in Photoshop), it’s best to start with the basics and work up, depending on how much control you want to have over the color

Working with in Photoshop is an art form, not a science—even when it comes to correcting color

Although the basic tools are fairly simple and straightforward, adjusting tonal curves takes a little practice and effort before you can do it well without thought, and adjusting color levels in the HSL panel can very quickly get out of hand! The best way to become proficient is to jump in and work with these tools until you feel comfortable using them to adjust the photos that really matter

Clarity, vibrance, and saturation

Clarity, vibrancy, and saturation can be adjusted in the basic panel of Camera Raw These adjust-ments are basic not because they are not powerful, but because they are so useful and commonly used that the default panel is the best place for them They also are the easiest of the color adjust-ments to use and to get right

As well as improving the color and clarity of your images generally, these settings can compensate for loss of color and clarity due to the tonal adjustments This is a great way to create stunningly colorful images, similar to taking pictures with a high-saturation film

You can adjust the clarity and saturation of your image by adjusting these sliders:

l Clarity: This adjustment clarifies the edges in the image, restoring definition and sharpness

lost to the tonal adjustments It works by increasing the contrast of the midtone pixels This works like magic to reduce hazy or dull images that are a result of the conditions when the image was shot or using other settings that reduce contrast, such as the Brightness slider

See the difference in the before and after images in Figure 8.14, for instance The first image is very hazy and blah The second image takes advantage of the Clarity adjustment

to make a dramatic difference in the clarity and crispness of the image

On the Web Site

Try your hand at adjusting the clarity of the before image saved as Figure 8-14 on the Web site n

l Vibrance: This adjustment saturates only the areas of the image that are of a lower

satura-tion without affecting the areas that are already highly saturated It also leaves skin tones alone, making it ideal for saturating images with human subjects

l Saturation: This adjustment saturates the image uniformly, giving you the ability to

reduce the colors in your image to grayscale or to increase the color of your image to as much as double the saturation Colorful photos, such as flowers or balloons, are especially fun to over-saturate in order to create a color statement