Photoshop cs5 cho nhiếp ảnh gia part 19 pps

Using the Brightness and Contrast Sliders The brightness slider shifts the majority of the pixels lighter or darker to make the overall image appear lighter or darker.. If you “expose to

Note: If you overexposed or underexposed the image to the point that you didn’t capture some of the highlight or shadow data, the Recovery and Fill Light sliders will not be able to recover it It can’t create infor-mation that you didn’t capture But if you were able to capture it on the sensor, then the Recovery slider will reveal it Remember that the sensor contains more information than can be displayed initially—usually up

to about 1/2 stop more information in the highlights and up to 11/2 stops more information in the shadows

set the Fill Light slider as necessary to recover detail in the darkest shadow areas You may need to modify the blacks slider setting as well The trick is that you still want some true blacks in your image, but you want to see detail in the not-quite-black shadow areas

Using the Brightness and Contrast Sliders

The brightness slider shifts the majority of the pixels lighter or darker to make the overall image appear lighter or darker watch how the bulk of the histogram shifts as you move this slider each way it’s similar to moving the center slider within Levels in Photoshop

The more extreme the adjustments you make with the exposure slider, the more likely it

is you’ll need to make adjustments using the brightness slider don’t forget to keep an eye out for any clipping you may introduce by increasing or decreasing the brightness

The Contrast slider is similar to applying an s curve within Curves in Photo-shop to increase or decrease the contrast within the bulk of the pixel values if you watch the histogram as you adjust this slider, you’ll see the bulk of the pixels being shifted away from the middle toward the extremes

Contrast is primarily modified in those pixels in the middle tonalities, with the lightest and darkest tonalities being less affected increasing the amount to greater than the default of +25 lightens values above the midtones and darkens values below the mid-tones similarly, reducing the value darkens values above the midtones and lightens values below the midtones to reduce the overall contrast if you decide to adjust the contrast in ACr, be sure to check that you have not introduced any clipping to your highlights or shadows You may have to readjust the other sliders

Note: Given the ability to make some fairly dramatic changes in exposure, it may seem as if you don’t have to worry about capturing the correct exposure in-camera In fact, as discussed in Chapter 1,

“Thinking Digitally,” the better your initial exposure, the better the final product will be If the image is initially underexposed, you’ll find that although you can correct the exposure, there is likely to be a lot

of distracting noise in the final image If you “expose to the right” (again, see Chapter 1), you will have the least amount of noise within your image, although you may have to adjust the Blacks slider, and possibly the Brightness slider as well Exposing to the right with raw captures ultimately gives you the best possible result as long as you make certain you don’t clip the highlights

Modifying Clarity, Vibrance, and Saturation

The Clarity slider is sometimes called the “make-it-better” slider, and we use it on most

of our images when the slider is adjusted to the right, it increases midtone contrast

as well as adding a small amount of sharpening that slightly increases the amount of

detail apparent in the image This can make an image seem to “pop.” when the slider

is moved to the left, the details in the image become progressively more blurred and in

some cases, the image may appear to glow That can be helpful for more artistic,

cre-ative interpretations of certain images some photographers we know routinely advise

pulling the Clarity slider all the way to the right we suggest caution because applying

too strong a Clarity adjustment can create artifacts we advise zooming in to a 100%

magnification to check for artifacts after initially setting the slider

both the saturation and Vibrance sliders affect the saturation or purity of col-ors in an image saturation increases the purity of all colcol-ors equally whereas Vibrance

is a “smart” saturation tool it affects colors differentially as it increases (or decreases)

the saturation to reduce the chances of introducing clipping in any color instead of

applying increased saturation uniformly to all colors, Vibrance applies it heaviest to

the less saturated colors and less to the more saturated colors it also tends to saturate

yellows and oranges less in order to try to preserve skin tones Although nature

pho-tographers are not often concerned with skin tones, we may want to saturate some

colors more than others in fact, we find that the Vibrance slider often creates a more

pleasing result we find that we can use higher settings with the Vibrance slider and

create images that pop but still look natural

At times you may want to use the saturation slider in addition to or instead of the Vibrance slider be sure to check for unexpected clipping within the different color

channels

The saturation and Vibrance sliders affect all the colors in your image if you want

to adjust specific color ranges, use the hsL/grayscale tab, which we’ll cover shortly

Note: Some images may benefit from reduced saturation or vibrance Be sure to watch the histo-gram as you make any changes

Setting the Other Tabs

ACr includes a total of 10 tabs, as shown in Figure 3.13, that have features to help you

optimize your image many photographers are more than happy with the results they get

simply by adjusting the sliders on the basic tab however, if you want to have even more

control, you should venture into these other tabs after you’ve made your initial

correc-tions on the basic tab we’ll describe how to use the other tabs in the order they appear

Figure 3.13 Click each of the tabs to reveal

additional tools to fine-tune and adjust your image

Setting the Tone Curves: The Tone Curve Tab

ellen calls Parametric Curves “easy Curves” because they’re much easier and more

intui-tive for novices to use but in addition to being easy, they’re quite powerful and useful

we routinely start with the Parametric Curves in ACr As shown in Figure 3.14, there are four sliders beneath the Parametric Curves graph, and the histogram is superimposed within it Adjusting the highlights slider primarily adjusts the brightest quarter of the tonalities Adjusting the Lights slider primarily affects the midtones to light tones but may affect the lightest tonalities or the darks as well The effect is most pronounced within the midtones to light tones The darks slider primarily affects the middle to darkest quarter

of tonality, while the shadows slider affects the darkest quarter of tonal values As you adjust any of these sliders, the more dramatic the adjustment you make, the wider the range of tonal values that will be affected To change the tonal range controlled by each slider, click on the triangles at the bottom of the graph and move them left or right

Figure 3.14 Creating customized curves

to adjust midtone contrast is easy using the Parametric Curve slider controls

we suggest you spend a little time experimenting with these sliders and getting comfortable with them They can be quite useful

Note: Parametric Curves are also available in Lightroom and Elements 8.0, but not in the Ele-ments version of ACR, and not within Photoshop itself

The Tone Curve tab offers another tab to access the Point Curve This is the type of curve that is found in Photoshop

when you click the Point tab (illustrated in Figure 3.15), you’ll see a drop-down menu for the Tone Curve, which by default is set to medium Contrast You’ll also see a graph showing the actual tone curve superimposed over a graph showing the distribu-tion of pixels by clicking within the drop-down menu, you can choose the Linear Curve option, which causes no additional contrast to be added to your image, or the strong Contrast option, which uses a preset tone curve that adds more contrast to your image

however, the really useful part of the Point tab is that you can begin with any

of the Tone Curve presets and modify the curve, using the preset points as well as any points you want to add, to create a custom curve for each image The advantage of doing this in ACr rather than later in Photoshop is that the curve is still operating on the linear data As long as you have the clipping preview boxes checked in the histogram

in ACr, you can see whether the changes you make are causing any clipping if you’re

comfortable using curves, you may want to experiment with the Point Tone Curves

within ACr if curves are new to you, you may want to stick with Parametric Curves

until you are more familiar with using them

Figure 3.15 By using the Point tab, you can access

various preset tone curves or make a custom curve to further refine your image

Note: By holding the Ctrl/F key and hovering the cursor over a pixel in the image preview, a circle will appear on the tone curve indicating where that point falls To create a point on the curve at that location, click while holding the Ctrl/F key

Sharpening and Reducing Noise: The Detail Tab

reduction

it’s important to remember that the sharpening you’re applying in ACr is a first pass only The final sharpening should be based on the output size of the image

Therefore, your setting should be conservative we often use the default settings

however, you may want to adjust them

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the edges

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very fine details, it may need a lower setting, and if it has larger details, it may benefit from a larger radius however, large radius settings can cause unnatural results, so be careful

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halos to emphasize the edges Lower settings remove blurring from edges, whereas higher settings make textures more pronounced

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the image receives the same amount of sharpening, while at 100 sharpening is restricted to areas near the strongest edges

Zoom in to 100% magnification and experiment with the sliders err on the side of caution and avoid oversharpening, which can cause obvious halos and/or a crunchy appearance noise reduction has been significantly improved in Cs5 There are now several sliders to help control luminance noise, in addition to sliders to mini-mize color noise These algorithms are so powerful that you may find you rely far less

on third-party noise-reduction software than in the past

noise is a by-product of digital captures, and is more problematic when using higher isos, making extremely long exposures, and/or correcting underexposed images

it’s a bigger problem with some cameras than with others noise may be seen primar-ily in areas of darker tonalities, although it can extend into the midtones as well (see Figure 3.16) noise appears as variations in tones and colors in areas that should be smooth, such as skies or skin

Luminance noise refers to grayscale noise, the unexpected and unwanted varia-tions in tonal values that appear This type of noise is similar in appearance in many ways to film grain by reducing these tonal variations, this type of smoothing may reduce the overall sharpness of your image, so keep these corrections to a minimum

it’s a good idea to zoom in on various critical areas of your image to 100% or even 200% to see how they’re being affected as you make adjustments

Cs5 has improved the luminance noise reduction that’s available in ACr

rather than just the single slider it had in the past, there are now three sliders to adjust (see Figure 3.16), which enable you to have more control and to apply noise reduction more specifically

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apply when the slider is set to 0, no luminance noise reduction is applied

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noise moving the slider to the right preserves more detail but also may cause more luminance noise to remain Conversely, adjusting the slider to the left can decrease the amount of luminance noise in the image but may inadvertently also cause some details to be removed

Note: If you opt to have ACR use Process 2003, the Luminance Detail slider is disabled

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while setting it to the right may preserve more texture in the image, it may also cause more noise to remain moving it to the left helps create smoother, fine-grained results, but may inadvertently cause some image texture and detail to

be smoothed

since luminance smoothing can reduce overall sharpness and blur fine detail,

we still often prefer to do most luminance noise reduction in Photoshop rather than

in ACr That way, we can use a mask to apply it only to problematic areas and retain full detail in our subject matter however, the new algorithms in Cs5’s ACr are effec-tive enough to have us trying them

Luminosity and Color noise reduction

No noise reduction

Default noise reduction

Figure 3.16 Noise appears as

random variations in tones and colors

in areas that should be smooth Using the noise-reduction sliders is an easy way to eliminate it

The Color noise reduction sliders reduce color noise, the unexpected color vari-ations that often appear Although this noise is most common in the darker tonalities,

it can also sometimes be seen as green and magenta blobs in areas that should be neu-tral gray and as rainbow artifacts in the highlights Again, zoom to a 100% or 200%

view of the areas demonstrating problems with noise, and move the sliders to reduce the color variations make the minimum adjustment necessary to decrease the noise

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applied to thin, detailed, color edges higher settings will retain more color detail in the edges but may cause more color noise to remain At lower set-tings, more color noise suppression is applied, but this may result in thin edges becoming desaturated or in color bleeding

we tend to use the Color noise reduction sliders in ACr to remove as much color noise as possible when noise is an issue

Correcting Color: The HSL/Grayscale Tab

visual tool offering the ability to fine-tune each color range on a variety of parameters

For example, you can modify the yellows so that they are closer to orange or closer to green You can also adjust the saturation of the yellows and then the luminance—or lightness/darkness—of them This means you can make subtle—or not-so-subtle—

adjustments to individual color ranges in your image without affecting other colors

when you click the hue, saturation, or Luminance subtabs, the eight color range sliders change to gradients, as shown in Figure 3.17, indicating how moving the slider will change the appearance of the colors You set each color individually

Figure 3.17 By using the HSL controls, Ellen fine-tuned the colors in this sunflower image.