Sử dụng photoshop cs5 part 12 ppt

Increase the Highlights, Lights upper mid-tones, Darks lower midmid-tones, or Shadows value to lighten that tonal range and thereby raise the corresponding portion of the curve above the

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To apply tonal adjustments using the Parametric sliders in the Tone Curve tab:

1 Click the Tone Curve tab, then the nested

Parametric tab A–B Behind the curve you’ll see a static display of the current histogram

2 Increase the Highlights, Lights (upper mid-tones), Darks (lower midmid-tones), or Shadows

value to lighten that tonal range and thereby raise the corresponding portion of the curve above the diagonal line,C or reduce the value

to darken that tonal range and thereby lower that portion of the curve below the straight diagonal line) (A–B, next page) If you need

to intensify the contrast, try moving the Highlights and Lights sliders in opposite directions

3 After adjusting the sliders, you can move the

region control (located below the graph) to expand or contract the range of tonal values that each slider adjustment affects The left region control affects the Shadows slider, the right region control affects the Highlights slider (C–D, next page), and the middle region control affects the Lights and Darks sliders The more a control moves the curve away from the straight diagonal line, the more adjacent tonal ranges are affected; the more a control moves the curve closer to the diagonal line, the fewer adjacent tonal ranges are affected

➤ Except for the Recovery slider, the sliders in the Basic and Tone Curve tabs shouldn’t be pushed

to the extreme left or right

Using the Tone Curve tab

After making adjustments in the Basic tab, the next

step is to improve the contrast in the photo Using

the Parametric sliders in the Tone Curve tab, you

can adjust the highlights, lights, darks, and

shad-ows separately Although you could also adjust the

curve manually (employing the same techniques

as for a Curves adjustment layer in Photoshop), if

you don’t click and drag the curve in just the right

way, the image could become posterized For this

reason, we encourage you to use the sliders instead

If you use Adobe Photoshop Lightroom, the

Parametric curve and sliders here will look familiar

C The Lights adjustment darkened the upper midtones, and the Darks adjustment darkened the lower midtones

A In this photo, the highlights lack detail and the midtones lack contrast.

B In the Parametric tab (Tone Curve tab),

we reduced the Lights and Darks values, which had the effect

of lowering the mid-section of the curve.

Region controls

D The adjustment to the region control expanded the darkening effect of the Lights and Darks sliders, which further darkened both the light and dark tonal ranges In this final image, the exposure looks just right.

C We moved the middle region control to

the right (to 68), which had the effect of

lowering the midsection of the curve.

A To darken the highlights, we reduced

the Highlights value This had the effect

of lowering the top of the curve.

B To reduce the highlights, instead of moving a Tone Curve slider, we clicked the Targeted Adjustment tool, then dragged downward over a highlight area

This lowered the Highlights value (pushed some highlight areas into the upper midtone range) and recovered details, most noticeably in the clouds Overall, the image contrast is improved.

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Using the HSL/Grayscale tab

In the HSL/Grayscale tab, you can adjust the hue,

saturation, or luminance of individual colors The

sliders in this tab are powerful! (They can be used

as sliders or scrubby sliders.)

To adjust individual colors via HSL sliders:

1 Click the HSL/Grayscale tab, and

double-click the Hand tool to fit the image in the

preview.A

2 Click the nested Hue tab Move any slider to

shift that color toward its adjacent hues, as

shown in the bar For example, you could shift

the Greens toward yellow to make a photo

warmer, or toward aqua to make it cooler

3 Click the Saturation tab ( A–B, next page)

Move any slider to the left to desaturate a

color (make it grayer) or to the right to make it

more vivid (more pure) Avoid oversaturation,

to keep the photo from looking unnatural and

from becoming unprintable

➤ To make a sky look more vivid, increase the

saturation of the Blues and Aquas; or to

make a sunset warmer, increase the

satura-tion of the Yellows or Greens; or to make

the lighting look gray and hazy, lessen the

saturation of the Yellows or Greens

4 Click the Luminance tab ( C–D, next page)

Move a slider to the left to make that color

darker (by adding black) or to the right to make

it lighter (by adding white) Avoid overlightening

the colors, to prevent clipping of the highlights

A In the original photo, the sky lacks contrast and the greens and yellows

in the field are oversaturated

USING THE TARGETED ADJUSTMENT TOOL

you can apply local adjustments to a photo After choosing the tool, click a nested HSL tab or click

Luminance from the menu Next, drag over a specifi c color area to apply a correction: Drag upward or to the right to increase the slider values, or downward

or to the left to decrease those values The sliders corresponding to the color under the pointer will shift automatically

A In the nested Saturation tab of the HSL/

Grayscale tab, we reduced the saturation of the

Oranges and increased the saturation of the Blues.

B The Saturation adjustments lessened the intensity of the oranges in the field and added richness to the blues in the sky.

C In the nested Luminance tab, we lightened

the Oranges and Yellows and darkened the

Blues A negative Blues adjustment can

pro-duce an effect similar to a polarizing filter

used during a photo shoot.

D The Luminance adjustments lightened the colors in the field and darkened the colors in the sky Overall, the colors in the top part of this photo are now in better balance with those in the lower part.

➤ Choose a zoom level of 66% for the Camera Raw preview to see

a more accurate rendering of the adjusted pixels.

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All digital cameras produce some luminance (gray-scale) noise and color artifacts Although budget cameras tend to produce the most noise, it can also

be produced by a high-end camera if used with a high ISO (light sensitivity) setting to capture a poorly lit scene Before opening your photo into Photoshop, you should try to remove as much noise from it as possible, as it can become accentuated by image edit-ing When you follow these instructions, you’ll see that shifting one slider value often requires adjusting another

To reduce luminance and color noise using the Detail tab: ★

1 With a photo open in Camera Raw ( A, next

page), click the Detail tab and choose a zoom level of 200–300% for the preview

2 To reduce grayscale noise (graininess), increase

the Luminance value ( B, next page) Try a value between 20 and 70

3. Raising the Luminance value smoothed out the high-contrast edges in the photo To resharpen

those edges, raise the Luminance Detail value

(C, next page) Note that a high Luminance Detail value may reintroduce noise along the edges

➤ With the Hand tool (H), you can move the photo in the preview window, to examine different edges

4 Raise the Luminance Contrast value to restore

some edge contrast The effect of this slider is most noticeable in photos that contain a lot of noise

5 Defects such as color artifacts and random

speck-ling tend to be most noticeable on solid-color surfaces, particularly those in the shadow areas

To reduce these defects, increase the Color value

from the default value of 25 to around 40–50, depending on the subject matter of the photo

6. Raising the Color value may lower the intensity

of colors in areas of the photo that were poorly lit To restore some saturation and intensity to

those areas, increase the Color Detail value

(D, next page) from the default value of 50 to around 75, or until the color saturation looks just right To judge the overall effect of the settings you have chosen in this tab, lower the zoom level

Using the Detail tab

Via sliders in the Detail tab, you can preview and

adjust the sharpness of your photo, and also reduce

any unwanted color noise Using these

nondestruc-tive sharpening controls is the best way to apply

what is called capture, or input, sharpening

To sharpen edges using the Detail tab:

1 Click the Detail tab Aand choose a zoom

level of 100% for the preview Note: If the words

“(Preview Only)” display in the Detail tab, click

the Open Preferences button in the toolbox

In the Camera Raw Preferences dialog, choose

Apply Sharpening To: All Images, then click OK

2 In the Sharpening area, use the Amount slider

to adjust the edge definition For subject matter

that needs a lot of sharpening, such as hard

objects or architecture, set this slider to 100; if

less sharpening is needed, try a value of 50–60

➤ To evaluate sharpening in a grayscale preview,

Alt-drag/Option-drag the Amount slider

3 Alt-drag/Option-drag the Detail slider slightly to

the right to sharpen edge details and textures,

and Alt-drag/Option-drag the Masking slider to

around 50 to protect low-contrast areas with a

black mask and sharpen only high-contrast areas

A In the Detail tab, we adjusted the

Sharpening sliders.

A This is a close-up of a photo of a shop window

(viewed at a zoom level of 300%), with the Noise

Reduction: Luminance and Color sliders set to zero

(no noise reduction applied) Grayscale noise is

evident in the signage, and color artifacts are

evi-dent in the poorly lit interior behind the letters

D To remove color artifacts from the dark areas,

we increased the Color value to 60 This had the

effect of desaturating the colors, though, so to

revive the color saturation and intensity, our last

adjustment was to increase the Color Detail value

to 70 The final image is shown at left.

B To remove graininess from the letters, we

changed the Luminance value to 69, but this also

diminished the edge definition.

C To resharpen the

edges of the letters, we

increased the Luminance

Detail value to 78.