Tài liệu Photoshop cs5 by Dayley part 17 potx

FIGURE 4.18 Selecting colors using the Color Picker tool... The Color Picker tool also allows you to select colors from a color library such as a Pantone color.. FIGURE 4.19 Selecting a

An image with 32 bit per channel is considered an HDR (High Dynamic Range) image Typically, these images

are used in 3D rendering and advanced CGI animation effects n

Choosing Colors

Now that you understand about color and how it relates to different modes in Photoshop, the last thing you need to know is how to actually select a color in Photoshop You will be working with many different tools in Photoshop that require you to select colors to use

Remember that even in 8 bits per channel, you can choose from more than 16 million colors The following sections discuss the main methods that you will use to set and select colors

Using the Color Picker tool

The most common method of choosing a color is using the Color Picker tool shown in Figure 4.18 The Color Picker tool is launched by clicking the foreground or background tool in the Photoshop toolbox

The Color Picker tool allows you to select any color possible in Photoshop and gives you a wealth

of information The main areas of the Color Picker tool are the color chooser pane, the range slider, the new/current color view, and the color settings

The Color Picker lets you use the mouse to select the color of any pixel displayed in the pane The range slider lets you use the mouse to adjust the range of colors displayed in the Color Picker pane The new/current color view simply shows the current color on the bottom and the newly selected color on top for comparison purposes

FIGURE 4.18

Selecting colors using the Color Picker tool

The color settings allow you to change each individual aspect of color that Photoshop uses to define a color Selecting one of the color settings changes the types of color that can be displayed

in the color chooser pane Changing the value of one of the settings changes the selected color

This list describes the available settings in the Color Picker tool:

l H: Changes the hue of the color The hue values are based on a range of 0 degrees to 360

degrees Think of a color wheel where red is at 0/360 degrees, green is at 120 degrees, and blue is at 240 degrees The hue setting is one of the best to use when selecting colors because it allows you to quickly move to a specific color using the range slider

l S: Changes the saturation of the color The values are based on 0% to 100% A higher

sat-uration means more of the color, and a lower satsat-uration means gray If you have the color you want but you want a little bit different tone, this is the best option to select for the range view

l B: Changes the brightness of the color The values are based on 0% to 100% Higher

val-ues mean the colors are brighter, and lower valval-ues mean darker This is also useful when you have the color you want but you want to adjust the tone just a bit

l R: Changes the intensity of the red channel in the color The values are based on intensity

levels of 0 to 255 Lower values mean less red, and higher values mean more intense red

l G: Changes the intensity of the green channel in the color The values are based on

inten-sity levels of 0 to 255 Lower values mean less green, and higher values mean more intense green

l B: Changes the intensity of the blue channel in the color The values are based on intensity

levels of 0 to 255 Lower values mean less blue, and higher values mean more intense blue

l #: Specifies the hexadecimal code associated with the color This is useful for colors that

are specified in Web pages and for specifying a particular color without having to memo-rize multiple values

l L: Changes the lightness of the color The values are based on a luminosity of 0 to 100 Higher

values mean white, lower values mean black, and middle values specify the tone of the color

This is useful when you have the color you want but want to adjust the tone just a bit

l a: Changes the value of the a channel in the Lab color mode The values are based on

tones between −128 and 127, where −128 is green, 127 is pink, and 0 is gray

l b: Changes the value of the b channel in the Lab color mode The values are based on

tones between −128 and 127, where −128 is blue, 127 is yellow, and 0 is gray

l C: Specifies the percentage of cyan in the color The values are based on a range of 0% to

100%, where 0% is no cyan and 100% is full intensity cyan

l M: Specifies the percentage of magenta in the color The values are based on a range of 0%

to 100%, where 0% is no magenta and 100% is full intensity magenta

l Y: Specifies the percentage of yellow in the color The values are based on a range of 0%

to 100%, where 0% is no yellow and 100% is full intensity yellow

l K: Specifies the percentage of black in the color The values are based on a range of 0% to

Another nice feature of the Color Picker tool is the ability to add the color you have chosen to the Swatches panel This is especially nice if you have taken a long time to find just the right color To add the color to the swatch, click the Add to Swatches button and specify the swatch name to add the color to

The Color Picker tool also allows you to select colors from a color library such as a Pantone color

To select a color from a color library, click the Color Libraries button to bring up the Color Library dialog box shown in Figure 4.19 Select the library book, and choose the color To change back to the Color Picker, click the Picker button

FIGURE 4.19

Selecting a color from the Color Libraries tool in Photoshop

Using the Color panel

Another method of choosing a color is using the Color panel shown in Figure 4.20 The Color panel provides the option of quickly selecting a color based on one of the color models or using sliders to adjust the levels of the color channels To launch the Color panel, select Window ➪ Color from the main menu in Photoshop

The working components of the Color panel are the before/after view, the Slider tools, the color ramp, and the menu The before/after view allows you to see the original color as well as the newly selected color The color ramp at the bottom allows you to select a color from the ramp using the Eyedropper tool that becomes visible when the mouse is over it The Slider tools allow you to use the mouse to drag handles to quickly select the level for each available channel or to type in a spe-cific value

The menu of the Color panel provides the following options to change the color mode used to select colors:

FIGURE 4.20

Selecting colors from the Color panel tool in Photoshop

l Grayscale Slider: Sets the slider control to a single slider that adjusts the level of

gray-scale colors This tool is useful if you need to add gray without any other tone to the image

l RGB Sliders: Sets the slider control to three sliders that allow you to adjust the intensity

levels of the red, blue, and green channels

l HSB Sliders: Sets the slider control to three sliders that allow you to adjust the hue,

satu-ration, and brightness of the color

l CYMK Sliders: Sets the slider control to four sliders that allow you to adjust the intensity

levels of the cyan, yellow, magenta, and black channels

l Lab Sliders: Sets the slider control to three sliders that allow you to adjust the values of

the a, b, and luminosity levels in the Lab channels

l Web Color Sliders: Sets the slider control to three sliders that allow you to adjust the hex

code values of the red, green, and blue channels for Web images

l Copy Color as HTML: Copies the current color as the HTML code that gets inserted into

an HTML tag when building Web pages—for example, color=”#9999cc”

l Copy Color’s Hex Code: Copies the current color as the hexadecimal code that

repre-sents the red, green, and blue values—for example, 9999cc

l RGB Spectrum: Changes the color ramp to use the RGB spectrum for selecting colors

using the eyedropper

l CYMK Spectrum: Changes the color ramp to use the CYMK spectrum for selecting colors

using the eyedropper

l Grayscale Ramp: Changes the color ramp to use the grayscale ramp for selecting a shade

of gray using the eyedropper

l Current Colors: Changes the color ramp to use only the tonal values of the current color

The Current Colors ramp is useful when you have the color you want, but you want to change the tone a little

bit or when you want to use multiple tones of the same color in the image n

l Make Ramp Web Safe: Changes the color ramp to provide only the Web-safe palette for

selecting colors using the eyedropper

Using the Swatches panel

One of the simplest methods of choosing a color is using the Swatches panel shown in Figure 4.21

A swatch is just a set of colors combined together The Swatches panel displays the available colors

in the swatch either as thumbnails or a list To choose a color, simply click the one you want To launch the Swatches panel, select Window ➪ Swatches from the main menu in Photoshop

FIGURE 4.21

Selecting colors from the Swatches panel tool in Photoshop

Using the Swatches panel menu, you can select one of the following views to display the colors available in the swatch:

l Small Thumbnail: Displays the colors as tiny squares in the Swatch panel This view is

the most commonly used Typically, the colors are big enough to see and yet the panel doesn’t take up much room

l Large Thumbnail: Displays the colors as larger squares in the Swatch panel This view is

useful if you have colors that are very close to each other in the swatch Viewing larger squares makes it easier to distinguish between the colors

l Small List: Displays the colors as a list with tiny squares next to the color names in the

Swatch panel This view typically is used when you want to know the name of the color when selecting it Navigating large swatches from the list form is difficult

l Large List: Displays the colors as a list with large squares next to the color names in the

Swatch panel This view is almost never used because of the difficulty in scrolling through

to find a color

Using the menu in the Swatch panel, you also can save the colors in the current swatch as a cus-tom swatch as well as load and replace swatches You also can select from a list of swatches built into Photoshop

Tip

When you open a new swatch, it allows you to append it to the existing swatch This enables you to combine

swatches you commonly use into a single custom swatch that you can load later, allowing you to avoid

con-stantly switching between swatches n

Using the Eyedropper tool

Another way to select a color is to use the Eyedropper tool in the Toolbox This is by far the sim-plest method of selecting a color The Eyedropper tool works by selecting the color that the mouse

is currently over in the image when the left button is clicked

The downside to using the Eyedropper tool is that the color must appear in the image The upside

to using the Eyedropper tool is that the color appears in the image These two statements may appear to conflict; however, it depends on what you are trying to do

If the colors in the image are limited or you want to add a color that doesn’t exist in the image, the Eyedropper tool will not work for you However, if you are trying to use a color that matches the sur-rounding image, selecting a color from the image guarantees that it matches somewhere in the image

When using the Eyedropper tool, the options menu shown in Figure 4.22 will allow you to set the following options:

l Sample Size: Allows you to specify the size of the area of pixels beneath the Eyedropper

tool that are sampled to determine color when the mouse is clicked The default is 11 by 11, but you can specify ranges from a single pixel to 101 by 101 The total area of pixels is sampled and the average color is selected For images with a lot of variance, you will likely want to use a smaller sample size

l Sample: Specifies whether to sample pixels from all layers or only the current layer.

l Show Sampling Ring: When this option is selected a large ring, shown in Figure 4.22, is

displayed as long as you hold the mouse button down The color ring shows the current color on the bottom and the sampled color on top as you drag the mouse around the image Notice that the current color is black and the sample color is from the small patch

of blue in the image

Note

The Show Sampling Ring option is available only if you enable OpenGL drawing as described in Chapter 2 n

FIGURE 4.22

The Sampling Ring allows you to see the previous color on top as well as the current color under the

cur-sor on bottom

Using the Color Sampler tool

A subtool of the Eyedropper tool in the Photoshop Toolbox is the Color Sampler It looks like the Eyedropper, but has a crosshair in the icon The Color Sampler tool allows you to view channel settings for up to four channels As shown in the Info panel in Figure 4.23, the Color Sampler tool launches when a pixel is selected

To use the Color Sampler tool, select it from the Toolbox and use the mouse to select pixels in the image After a pixel is selected by left-clicking in the image, the Info panel is loaded As the mouse moves, the data at the top of the Info panel changes, telling you the values of the RGB and CYMK channels of the pixel that the mouse is over

You can add up to four samples to the Info panel using the Color Sampler tool To delete a sample, right-click the sample using Color Sampler tool and select Delete from the pop-up menu To change the color mode information listed in the Info panel, right-click the sample and select the color mode

FIGURE 4.23

Viewing color channel data in the Info panel in Photoshop

Using the HUD Color Picker

One of the best ways to quickly select a color while using another tool such as a brush is to use the HUD Color Picker shown in Figure 4.24 The HUD color picker provides a hue strip or wheel that sets the base tone for a color block An Eyedropper cursor in the color block allows you to select a specific color from the color block or a hue from the hue strip or wheel

The HUD Color Picker is launched by pressing Alt(Option)+Shift while right-clicking with the mouse Figure 4.24 shows both the wheel and strip versions of the HUD Color Picker Which version

is displayed is defined in the General settings of the Preferences dialog as discussed in Chapter 2

FIGURE 4.24

The HUD Color Picker is a very useful method to change the color while using other tools

Eyedropper

Color block Hue strip

Hue wheel

The HUD Color Picker is available only if you enable OpenGL drawing as described in Chapter 2 and in 8-bit

and 16-bit images n

Summary

This chapter covered everything about color, from how the human eye perceives it to how to select

a color in Photoshop The histogram shows you the basic composition of one or more color chan-nels, and modifying the histogram modifies the color composition in the image

The purpose this chapter was to familiarize you with the relationship between light, color, the human eye, digital files, and Photoshop You have learned the following:

l Color is simply light reflected off surfaces at different frequencies and intensities

l Photoshop sees colors in terms of channels and levels

l How to understand the information contained in a histogram and how it applies to the level and channels contained in the different color modes of Photoshop

l The purpose and how to best use each of the color modes such as RGB, CYMK, and grayscale

l Utilizing the color tools in Photoshop to give you the maximum information when editing your images