Photoshop cs5 cho nhiếp ảnh gia part 41 pdf

Painting on a Mask in some situations you don’t want to create the adjustment layer mask based on a selection.. Using the Color Range Option the Color range option, which is part of the

let’s consider an example to see how these panels work when you’re optimiz-ing your image Figure 6.14 shows the panels for an image where we want to lighten the subject rather than making a selection beforehand as you might have done in earlier versions of photoshop, open the Adjustments panel and click on levels Adjust the sliders to approximately where you think you want them then click the masks panel and choose Color range Click on the subject and use Color range to make the best selection you can then use mask Edges to tweak the edges now go back to the Adjustments panel and finalize the settings

Figure 6.14 Since CS5 is nonmodal, you can

have an adjustment dialog open while you are tweaking the mask and easily alternate between the mask and the dialog

Painting on a Mask

in some situations you don’t want to create the adjustment layer mask based on a selection When the edge of the area you want to adjust isn’t well defined, it’s often easier and more efficient to paint directly on the mask to control where the effect is visible the concept is that you paint with white or black on the mask to control the visibility of the effects of that layer

Almost all of us have been using a paintbrush since we were preschoolers, so creating a mask by painting is usually a very natural and intuitive approach to use this approach, take the following steps:

making the particular section of your image look the way you want, and don’t worry that the rest of the image may be “ruined.” We’ll use the layer mask to restore those areas to their “before” states

adjustment layer so it’s easier to see exactly where in the image the adjustment layer applies

use a soft brush (0% hardness), but in some instances you will want to use a harder brush or even a totally hard brush to make a discrete edge

4. press d to set the colors to their defaults of black and white, and then press x

as needed to switch foreground and background colors

Figure 6.13 By making adjustments using layer masks, you can help emphasize your subject by applying one type of adjustment

to the subject and a different one to the background

Using the Color Range Option

the Color range option, which is part of the masks panel in Cs5, offers an efficient

method to create a selection for the layer mask even if you’ve already begun setting

the adjustment layer You can use the options within the masks panel at any time

ini-tially the adjustment is set to affect the entire image unless you began with a selection

if you began the adjustment process by first creating a selection and then opening an

adjustment layer, the Color range control will operate only within that selection, not

across the entire image Color range becomes a way to limit the effect to a subset of

your original selection

When you click the Color range option, the Color range tool appears use

it the way we discussed in Chapter 4 to define the area you want the adjustment to

affect think of this as an automated way of controlling where to apply the

ment the ability to use the Color range tool while in the midst of making an

adjust-ment is extremely helpful

fore-ground color to remove the effects of your adjustment from that area

your foreground color then paint over the area to correct the mistake layer masks are very forgiving!

to help you see exactly where you have masked the image and where the effect will appear, press the \ key this will create a type of quick mask over your image A transparent red layer will appear over the masked areas, as shown in Figure 6.15 As you paint with black, the red area will increase; to remove the red from an area and allow the effect to be visible there, paint with white We know it’s a little confusing to paint with black and have it appear red, but remember you’re not really painting on the image You’re painting on the layer mask, and the red is there as a superimposed version of the mask that’s easier to see to remove the quick mask, press the \ key again this is one of our favorite tricks!

Figure 6.15 Pressing the backslash (\) key makes a red mask appear over the parts of your image that are masked,

helping you to see whether you need to refine the mask

in the Layers panel That way, the mask appears in place of your image preview, making it easy to clean

up small areas that may have been missed in painting

one of the benefits of using layer masks is that if you decide you need to further revise the layer mask, you can simply click the adjustment layer to make it active, and

paint as needed to change the areas where the adjustment is blocked or revealed

looking at the image, then Alt/Option+click on the mask in the Layers panel to see the mask preview

in place of the image That way they can more easily fill in the area within the outline When done, Alt/

Option+click on the mask icon again to return to the image preview

At times, you’ll want the adjustment layer to apply to a very small area of your image, but that area won’t be conducive to making a selection in such situations, it

may seem that the only solution is to paint with black throughout most of the image

An easier way is to begin with a layer mask that is already filled with black and then

paint with white on the areas where you want the effect to show to do this, take

these steps:

1. After creating the new adjustment layer, choose Edit > Fill from the menu

fills the layer mask with black, blocking the effect of the adjustment from the entire image

Figure 6.16 You can use the Fill command

to fill a layer mask with black and then paint with white to apply the adjustment to specific areas of the image

adjust-ment in the areas where you’d like it to be applied

and use Ctrl+Delete/F+Delete to fill a layer mask with the background color

so far you’ve seen how you can paint with black or white on an adjustment layer mask to target specific areas where the adjustment should be blocked or revealed

if you’d like to only partially block or reveal the effects of an adjustment layer, then the layer mask will need to be a shade of gray the darker the gray, the more the effect will be blocked, and the lighter the gray, the more it will be revealed, as shown in Figure 6.17 rather than using the Color picker to select a shade of gray (because it’s easy to accidentally select a non-neutral gray, which can lead to unexpected results),

we recommend continuing to use the default colors of black and white but reducing

the opacity of the brush to reduce the opacity of the brush, use the opacity box in

the toolbar options bar (not the layers panel) And, as we mentioned earlier, paint with a soft-edged brush if necessary to produce a gradual transition between the areas that are and are not affected by the adjustment layer When using a brush with lowered opacity, be careful because if you release the cursor and paint over the same spot again, the effect will be cumulative At times this may be exactly what you want

to happen! But at other times it could result in unexpected results if you accidentally overlap the edges of your brush strokes

Figure 6.17 You can use shades of gray on an adjustment layer mask to have the effect partially revealed within the image.

yield an opacity of 10%, 2 will give 20%, and so on Pressing 0 returns the opacity to 100%

mask You can set the pen so that the pressure you use determines the opacity of the brush That makes transitions smooth and intuitive

of course, you can also combine the two approaches to creating a mask You could start by creating a selection that defines the area you want to adjust, and then

paint on the layer mask to fine-tune the area you want to have affected by the

adjust-ment this allows you to utilize the best of both techniques to achieve the best results

possible in your images

create a rough selection of the interior of the flower using the Lasso tool Then create a Levels adjust-ment, lighten the interior of the flower, and click OK Then use the Brush tool to refine the initial selec-tion edge, painting with white where you want the selecselec-tion to apply and painting with black where you don’t want it to apply Try this exercise a second time using the new Color Range option

Refining the Layer Mask

We highly recommend that you take advantage of the vastly improved mask Edge

dialog accessible from the Cs5 masks panel to fine-tune the edges of your mask if you

began the layer mask from a selection otherwise the transition between the areas you

adjusted and those you didn’t will be relatively harsh, as you can see in Figure 6.18

sometimes this works well, but other times you may want a more natural transition

of course, if you created the mask by painting it or from Color range, it may still

benefit from the mask Edge controls the mask Edge dialog is identical to the refine

mask dialog we covered in Chapter 4; only the name is different!

Figure 6.18 When you use a nonfeathered selection or a hard-edged brush with a layer mask, the transition between adjusted

and nonadjusted areas will be relatively harsh Using Refine Mask leads to a more gradual, and often more natural, transition

For Photoshop Elements Users: Smart Brushes

Photoshop Elements provides two tools, the Smart Brush and the Detail Smart Brush, which combine the Quick Selection and the Selection Brush tools, respectively, with an adjustment and a layer mask They let you pick an adjustment and paint over the part of the image that you want to adjust Since they automatically create an adjustment layer, you are able to easily change the adjustment settings at any time

Continues

For Photoshop Elements Users: Smart Brushes (Continued)

The Detail Smart Brush differs from the Smart Brush in that the Smart Brush uses the Quick Selec-tion tool algorithms so that the areas that you paint are intelligently selected and expanded The Detail Brush uses the regular Selection brush so that any areas you paint over, but only those areas, are affected

To use the Smart Brushes follow these steps:

1. Select the Smart Brush icon in the toolbar

2. Choose an adjustment from the pull-down menu in the tool Options bar as seen here We find that the All Purpose, Lighting, and Nature categories tend to have the most useful options for nature photographers

3. Adjust the brush size and paint over the image to apply the adjustments Elements will drop a “pin” onto the image that connects to the controls for the adjustment

4. Right/Ctrl+click on the pin and choose Change Adjustment Settings to open the Adjust-ments panel containing the adjustment Tweak any of the settings and the area you ini-tially brushed over will update immediately

5. Use a combination of the Add to Selection and Remove from Selection icons , as well as the Refine Mask dialog to refine the mask The tool Options bar also has controls to refine your brush settings

6. If you’re not happy with an adjustment, right-click/Ctrl+click on the pin and choose Delete Adjustment

7. To make additional Smart Brush adjustments, click the triangle on the left edge of the tool Options bar and choose Reset Tool Start painting on an area to create a new adjustment

As you make additional adjustments, you can switch between them by either clicking on the appropriate pin or by right-clicking/Ctrl+clicking on any pin and choosing the desired pin from the context menu

Curves

difficult controls to master Although becoming comfortable with it can take some

time and practice, it provides an incredible level of control over your images it enables

you to change the brightness values and contrast within your image by applying

vary-ing degrees of adjustments to pixels of different tonal values simply put, you can

con-centrate contrast or brightness modifications in certain tonal ranges As with levels,

you can accomplish similar effects within ACr, but the Curves tool in photoshop has

some features that make it more convenient

the key to understanding the Curves adjustment is the concept of “before” and

“after” values All adjustments in Curves are based on shifting the value of all

pix-els at (or near) a particular tonal value therefore, think in terms of brightening the

midtones or darkening the highlights, for example, when working with Curves the

Curves dialog box shows a “curve” overlaid on a grid (see Figure 6.19), all of which

is superimposed over the histogram of course, at first the curve isn’t a curve at all,

but a straight line at a 45° angle As you learn to “read” the curve, you’ll see that this

45° line represents no change in the image the gradient along the bottom of the grid

represents the before tonal values, and the gradient at the left shows the after values

if you follow a vertical line up from a specific tonal value on the gradient below the

grid to the point that intersects the curve line, and then you follow in a straight line to

the left until you reach the after gradient, at this point the before and after values are

exactly the same Changing the shape of the curve alters the relationship between the

before and after values, resulting in a change in the appearance in your image

Figure 6.19 The Curves dialog box shows a “curve” that

by default is actually a straight line at a 45° angle

the grid behind the curve line is provided simply for reference, and you can set it to either a 16-square grid or a 100-square grid in general, the 16-square grid

is preferred by those working in prepress, because they tend to think about quarter

tones, midtones, and three-quarter tones however, most photographers prefer the

100-square grid, and that is the setting we recommend to toggle between the two

settings, hold the Alt/option key, and click the cursor anywhere within the grid

keep in mind that changing the increments has absolutely no effect on the actual adjustment being applied

Clipping Preview

to check for clipping, go to the Curves fly-out menu and toggle on show Clipping for Black and White points, then click and drag the white or black points—that is, the points at either extreme of the curve the image turns either nearly or all white, or nearly or all black A white background is used to check for clipping in the shadows, and a black background is used to check for clipping in the highlights Any areas where there is clipping will appear in color to indicate the particular channel that’s being clipped, and if all three channels are clipped, then the area will appear black or white—whichever is the opposite of the background color this makes it easy to see where there’s any clipping and to decide whether you need to modify your adjustments

to try to eliminate it sometimes the clipping will be in dark shadows that should be black or in specular highlights that should be pure white At other times the clipping preview may show you that you’ve unintentionally lost detail in your subject

You can use the clipping preview to accurately set the white and black points in your image Click the small white triangle on the bottom right of the histogram the image will turn black then drag the triangle to the left until colored pixels begin to appear in the preview Back the slider off until there is no clipping, if possible that sets the white point repeat the process with the small black triangle on the bottom left of the histogram to set the black point

dragging the triangles toward each other will increase the contrast in the image and eventually introduce clipping Again, for the maximum amount of contrast in your image, drag these sliders toward the center until colored pixels appear, and then back off slightly then, to change the overall brightness of the image or to refine the contrast within a certain range of tonalities, apply anchor points to the curve

Anchor Points

You use anchor points for changing relationships between the before and after values in your image, which in turn creates the actual tonal adjustment Anchor points allow you

to place a handle on a particular point on the curve and adjust its position When you

do so, photoshop automatically smoothes out the curve to connect all the anchor points, providing a seamless transition in your adjustments

the curve always starts off with anchor points at the extreme ends You can adjust the position of these points by setting the black points and white points within your image as we just described in the “Clipping preview” section

to see the basic functionality of anchor points, position your mouse at about the middle of the curve, and click this places an anchor point at that position; then you can drag it around to change the shape of the curve, as you can see in Figure 6.20

move the anchor point upward to lighten the image and downward to darken the image the result is similar to adjusting the midtones slider in levels it differs in that the tones closest to the point you moved on the curve are altered more than tones far-ther away from that point in fact, the effect tapers off toward the ends of the curve