Tài liệu Photoshop cs5 by Dayley part 59 pps

n Creating customized black and white photos When you convert a color image into a black and white photo, you are really combining three channels red, green, and blue of data into only o

On the Web Site

The image shown in Figure 13.16 can be found on this book’s Web site as Figure13-16.jpg Check out the file

on the Web site and make the changes shown in the example to see the detail come back and the brightness

get toned down n

Creating customized black and white photos

When you convert a color image into a black and white photo, you are really combining three channels (red, green, and blue) of data into only one grayscale channel This can be done in any number of ways However, there are three main concepts

One way to convert a color image to grayscale is to use only one of the three channels, for exam-ple, only the red channel The problem is that this gives you only the red data in the image, leaving much of the detail out This works well for some effects, but you likely want more detail in your image

Another way is to use a combination of the three channels For example, you could create grayscale data by taking 40 percent of the red value, 40 percent of the green value, and 20 percent of the blue value and adding them together to get the value for each grayscale pixel By using the best combination of the three channels, you can get the most detail out of the image This works very well, as you learned in the Channel Mixer section of Chapter 11 In fact, this is the default method that Photoshop uses to convert color images to grayscale and is the recommended method of con-version

A little bit more complex way to generate the grayscale data from the color channels is to focus on percentages of each color tone This allows you to maximize the amount of detail, best contrast, and overall appearance of the resulting black and white photo The drawback to this method is that it requires some guesswork and a bit of trial and error to get the best effect

The Black and White Adjustment tool, shown in Figure 13.17, allows you to use combinations of reds, greens, and blues, as wells as cyans, magentas, and yellows to generate the grayscale data in the black and white image By specifying percentages of these color tones, you can customize the resulting levels that go into the grayscale channel of the black and white photo

Tip

When you use the Black and White Adjustment tool to create black and white photos, keep in mind that

increasing the percentage of a color lightens those pixels in the resulting image Decreasing the percentage of a

color darkens those pixels in the resulting image For example, if you want to darken the sky in the black and

white photo, you would decrease the percentage of blue that is included in the resulting image n

To use the Black and White Adjustment tool to create a customized black and white photo, select Image ➪ Adjustments ➪ Black & White from the main menu in Photoshop to launch the Black and White dialog box shown in Figure 13.17 Then use the adjustment sliders to set the amount of each color to include when creating the grayscale channel

FIGURE 13.17

Using the Black and White Adjustment tool, you can create customized black and white photos using

combinations of the red, yellow, green, cyan, blue, and magenta colors in a color image

Note

The percentages of all colors in the adjustment tool do not need to equal 100 percent In fact, if they do, the

image likely will be too dark Because the cyan, yellow, and magenta channels are combinations of the red,

green, and blue channels and vice versa, there is lots of overlap Just keep in mind that as you increase or

decrease the total percentage, the overall brightness of the black and white photo is increased or decreased n

A nice feature of the Black and White Adjustment tool is the ability to add a tint to the resulting image This is a great way to create a sepia effect in the image because the tint takes into account the current color values along with the adjusted percentages when creating the overlaying tint

To add a tint to the resulting black and white image, select the Tint option shown in Figure 13.17

Then adjust the Hue setting until you have the correct color in the tint Then adjust the Saturation setting to set the appropriate density of the tint After adjusting the saturation of the tint, you may need to tweak the hue a bit to adjust for the change in tone

Hue and Saturation

The hue and saturation factors are by far the most important properties that define the color in an image Hue refers to the actual color tone the pixel in the image appears to the eye Hue is mea-sured in degrees around the color wheel, where 0 degrees and 360 degrees are red, 120 degrees is green, and 240 degrees is blue

Saturation refers to the difference of the color against its own brightness—in other words, how brilliant the pixel appears to the eye Low saturation means almost gray, and high saturation is the fully brilliant color

You adjust the hue and saturation of images for two main reasons One is to change the color tones that were affected by adverse lighting, such as a yellow cast caused by fluorescent lights The sec-ond is to bring back the intensity of colors that is lost due to the use of filters, haze, limited light-ing, or other adjustment made in Photoshop This section discusses using the Hue/Saturation Adjustment tool to fix the color tones in images

Using the Hue/Saturation tool

The most important tool you can use to adjust the color in images is the Hue/Saturation Adjustment tool shown in Figure 13.18 Using the Hue/Saturation Adjustment tool, you can change the hue, saturation, and lightness of all colors in the image, or you can adjust specific colors

FIGURE 13.18

Using the Hue/Saturation Adjustment tool, you can make both specific and general adjustments to the

col-ors in an image

Presets Color channel On-image adjustment tool

The Hue/Saturation tool can be accessed by selecting Image ➪ Adjustments ➪ Hue and Saturation from the main menu or by adding an adjustment layer to the image From the Hue/Saturation tool, shown in Figure 13.18, you can set the following options:

l Presets: Allows you to select one of Photoshop’s predefined presets or one of your own

saved You can save the settings you make in the Hue/Saturation tool as a preset by select-ing the Save Hue and Saturation presets from the Adjustments panel menu Photoshop provides the following presets to quickly adjust the hue and saturation of images:

l Default: Uses the middle values for hue, saturation, and lightness.

l Cyanotype: Applies a blue monotone effect to the entire image.

l Increase Saturation More: Increases the saturation of all colors by +30, giving a

larger saturation boost to make the colors stand out more

l Increase Saturation: Increases the saturation of all colors by +10, giving a slight

satu-ration boost to make the colors stand out

l Old Style: Decreases the saturation by −40 to reduce the amount of color in the

image Lightness also is increased by +5 to compensate for the lost color

l Red Boost: Decreases the hue by −5 and increases the saturation by +20 to make the

reds pop out more

l Sepia: Makes the image a monotone by selecting Colorize and adjusting the hue to

red and the saturation down to only 25 to give the image a sepia look

l Strong Saturation: Increases the saturation of all colors by +50, giving a huge

satura-tion boost to make the colors really stand out

l Yellow Boost: Increases the hue by +5 and increases the saturation by +20 to make

the yellow colors pop out a bit

l Custom: Allows you to make your own changes to the hue, saturation, and lightness

in the image

l Color Channel: Allows you to select the Master color channel to change all colors or

select the red, yellow, green, cyan, blue, or magenta color tones

Note

If you adjust the adjustment color outside of the tonal range for that color into another color’s tonal range, the

color channel name changes to the new color tone For example, if you select the red color channel and adjust

it to green, the Adjustment color list displays Green 2 instead of red for the color channel n

l Hue: This adjusts the hue of the selected color channel based on the location of the slider

or the value in the text box

l Saturation: This adjusts the saturation of the selected color channel based on the location

of the slider or the value in the text box Increasing the saturation makes the colors brighter, and decreasing the saturation dims the color toward gray

l Lightness: This adjusts the lightness of the selected color channel based on the location of

the slider or the value in the text box

l On-image Adjustment tool: The On-image Adjustment tool is a great way to adjust the

hue or saturation of a specific color in the image When you select the On-image Adjustment tool, the mouse cursor changes to an eyedropper Simply select the color you want to change in the image, and drag the mouse to adjust the saturation The color chan-nel changes to match the color of the selected pixel As you drag the mouse left, the satu-ration decreases, and as you drag the mouse to the right, the satusatu-ration increases To adjust the hue, hold the Ctrl/Ô key down when you select and drag on the image The color channel changes to match the color of the selected pixel As you drag the mouse left, the hue moves toward the yellow side of red, and as you drag the mouse to the right, the hue moves toward the magenta side of red

l Eyedropper tools: The eyedropper tools allow you to define the hue of color channels by

clicking specific pixels in the image This allows you to use real pixels in the image to define colors The eyedropper tools are not available when the Master color channel is selected The regular eyedropper sets the middle of the color channel to the value of the pixel selected in the image When you use the plus eyedropper, the color of the selected pixel is added to the color channel, increasing the tonal range When you use the minus eyedropper, the color of the selected pixel is removed from the color channel, decreasing the tonal range

l Colorize: The Colorize option is used to either add color to a grayscale image or to create

a monotone image from a color image The color channels are flattened, and the hue, satu-ration, and lightness values apply to the entire image The only color in the image is the color range of the current hue value

l Adjustment slider: The Adjustment slider is the most powerful feature of the Hue/

Saturation tool The Adjustment slider allows you to specifically define the range of the colors being affected by the hue, saturation, and lighting You also can define how the color boundaries are feathered out into other colors To use the Adjustment slider, use the mouse to drag and adjust the following areas, as shown in Figure 13.19:

FIGURE 13.19

Using the Adjustment sliders of the Hue/Saturation Adjustment tool, you can specify both the specific color range and the surrounding fallout ranges that are used to feather adjustments

Left falloff hue Left range hue

Hue range area

Right range hue Right falloff

Left falloff handle Left fallout area Left range handle Right range handle

Right fallout area Right falloff handle

l Left Falloff Handle: Adjusts the area of the left falloff used to feather the color

correc-tion into other colors Increasing the falloff area results in more feathering of the color changes into the adjacent colors Adjusting this handle does not affect the hue range

at all

l Left Fallout Area: Moves the left fallout area The size of the left fallout area is not

affected by the change However, the hue range is increased or decreased

l Left Range Handle: Adjusts the area of both the hue range and the left fallout area

As the range increases, the left area fallout decreases and vice versa

l Hue Range Area: Moving this area moves the entire set of handles without changing

the respective sizes The hue range area specifies the colors directly affected by the hue, saturation, and lightness changes Increasing the range area includes more of the adjacent tones in the correction, just as decreasing the range area focuses on a specific color You may need to vary this setting for specific needs For example, if you want to correct a specific color, then you want the range to be as small as possible

l Right Range Handle: Adjusts the area of both the hue range and the right fallout area

As the range increases, the right area fallout decreases and vice versa

l Right Fallout Area: Moves the right fallout area The size of the right fallout area is

not affected by the change However, the hue range is increased or decreased

l Right Falloff Handle: Adjusts the area of the right falloff used to feather the color

cor-rection into other colors Increasing the falloff area results in more feathering of the color changes into the adjacent colors Adjusting this handle does not affect the hue range at all

Adjusting the hue and saturation to make colors pop

The biggest strength of the Hue/Saturation Adjustment tool is the ability to make hue, saturation, and lighting changes to specific color ranges This allows you to fix certain colors in an image with-out affecting other colors The following example demonstrates how to use the Hue/Saturation Adjustment tool to enhance the colors in an image:

The colors in this particular image are really dulled down by the haze that was present the day the photo was taken

Adjustments panel shown in Figure 13.21.

and Saturation Adjustment layer to the image and open the Hue/Saturation tool.

red up to +50

This will make the red colors in the leaves pop out much more

FIGURE 13.20

The colors in this image are very dull and a bit washed out by the haze present when the photo was taken

FIGURE 13.21

Selecting the Hue/Saturation option from the Adjustments panel in Photoshop adds an adjustment layer to the image and launches the Hue/Saturation Adjustment tool

shown in Figure 13.22

This helps the yellow and orange leaves a bit more.

The blue colors present a problem We want to correct the blue in the sky and the water

but not affect the other colors so much So we tighten down the range, as shown in Figure 13.22 We also increase the size of the right fallout area to allow the blue changes

to feather over a bit into the magentas and reds

7 After the blues range is set, adjust the saturation up to +50 to bring out the blue in

the sky and water and adjust the Hue to +25 to change the sky and water to a richer tone of blue.

FIGURE 13.22

Adjusting the saturation of reds and yellows in the image makes the color of the leaves stand out much more Using the Adjustment sliders to change the range of blues allows you to focus in on the sky without affecting the other colors

On the Web Site

The project used to create the image shown in Figure 13.23 can be found on this book’s Web site as

Figure13-23.psd Because the book is in black and white, you cannot really see the adjustments in the image in

the book Check out the file on the Web site to see the color changes in effect You can open it in Photoshop

and make your own changes to the Hue/Saturation Adjustment layer to see the effect on the image n

FIGURE 13.23

Using the Hue/Saturation tool, you made the red and yellow leaves pop out and changed the color and intensity of the sky and water to give the photo a brilliant color tone

Levels

The most basic adjustment you can make to an image to change the color and lighting is to change the level composition of the color channels in the image Adjusting the level composition can restore detail in areas of an image and fix a variety of lighting problems

Photoshop provides the Levels Adjustment tool to give you direct access to the levels of the color channels You can access the Levels Adjustment tool by selecting Image ➪ Adjustments ➪ Levels from the main menu or by selecting a Levels adjustment in the Adjustments panel

This section discusses how to configure and use the auto levels adjustment as well as making cus-tom levels adjustments to your images

Cross-Ref

The concept of color channel levels was introduced in Chapter 4 You should read that chapter before reading

this section because you need to understand the concepts from Chapter 4 to get the most out of using the

Levels tool n