Sử dụng photoshop cs5 part 12 ppt

ptg 72 Chapter 4 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 midtones), 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 aects. e left region control aects the Shadows slider, the right region control aects the Highlights slider ( C–D , next page), and the middle region control aects the Lights and Darks sliders. e more a control moves the curve away from the straight diagonal line, the more adjacent tonal ranges are aected; the more a control moves the curve closer to the diagonal line, the fewer adjacent tonal ranges are aected. ➤ 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  e L i g h t s a d j u s t m e n t d a r k e n e d t h e u p p e r m i d t o n e s , 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 eect of lowering the mid- section of the curve. Region controls ptg Camera Raw 73 D  e a d j u s t m e n t t o t h e r e g i o n c o n t r o l e x p a n d e d t h e d a r k e n i n g e  e c t o f t h e Lights and Darks sliders, which further darkened both the light and dark tonal ranges. In this nal image, the exposure looks just right. C We moved the middle region control to the right (to 68), which had the eect of lowering the midsection of the curve. A To darken the highlights, we reduced the Highlights value. is had the eect 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.  i s l o w e r e d t h e H i g h l i g h t s v a l u e ( p u s h e d s o m e h i g h l i g h t a r e a s i n t o t h e u p p e r midtone range) and recovered details, most noticeably in the clouds. Overall, the image contrast is improved. ptg 74 Chapter 4 Using the HSL/Grayscale tab In the HSL/Grayscale tab, you can adjust the hue, saturation, or luminance of individual colors. e sliders in this tab are powerful! (ey 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 t 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 eld are oversaturated. USING THE TARGETED ADJUSTMENT TOOL With the Targeted Adjustment tool in Camera Raw, you can apply local adjustments to a photo. After choosing the tool, click a nested HSL tab or click and hold on the tool and choose Hue, Saturation, or 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. ptg Camera Raw 75 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  e S a t u r a t i o n a d j u s t m e n t s l e s s e n e d t h e i n t e n s i t y o f t h e o r a n g e s i n the eld 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 eect similar to a polarizing lter used during a photo shoot. D  e L u m i n a n c e a d j u s t m e n t s l i g h t e n e d t h e c o l o r s i n t h e  e l d a n d 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. ptg 76 Chapter 4 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 dierent edges. 4. Raise the Luminance Contrast value to restore some edge contrast. e eect 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 eect 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 A and 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 denition. 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. ptg Camera Raw 77 A  i s i s a c l o s e - u p o f a p h o t o o f a s h o p w i n d o w (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. is had the eect 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. e nal 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 denition. C To resharpen the edges of the letters, we increased the Luminance Detail value to 78. . 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. 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  e L i g h. 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