Photoshop cs5 cho nhiếp ảnh gia part 20 docx

The Color noise reduction sliders reduce color noise, the unexpected color vari-ations that often appear.. Again, zoom to a 100% or 200% view of the areas demonstrating problems with noi

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.

Clicking the saturation or Luminance tabs changes the eight color sliders so that they reflect increased and decreased saturation or modifications in luminance

spending the time to fine-tune the colors in your image may not be something you do to every image, but for some images, these tweaks can take an image from

ordinary to extraordinary!

if you checked the Convert to grayscale option on the basics tab, then a gray-scale mix tab will appear in place of the hsL tabs Adjusting the sliders for each color

lightens or darkens that color range by using these sliders, you can alter the contrast

within your image and create dramatic black-and-white versions of your images, as

shown in Figure 3.18

Figure 3.18 A Straightforward grayscale conversion is often lackluster, but by using the grayscale controls

you can create a more vibrant image

Alternate Interpretations: The Split Toning Tab

photography however, you may well find that a specific image lends itself to this creative interpretation based on a grayscale version of the file The concept (seen in Figure 3.19) is that you assign one color for the highlights and a different color for the shadows so that you “split” the tones of the image

Figure 3.19 A Split Tone version of this image increases the feeling of fall colors but may or may not be to your taste.

Fixing Aberration and Vignetting: The Lens Corrections Tab

fringing (chromatic aberrations)—that may result when using particular lenses with

dig-ital cameras some photographers either never have these problems or never notice them,

and that’s fine others perceive them readily and are quite bothered by them

Chromatic aberration, also known as fringing, occurs when the lens fails to focus the red, green, and blue wavelengths of light on exactly the same plane (the camera’s

image sensor); this causes color fringes along high-contrast edges Chromatic aberration

seems to be more of a problem with wider-angle shots, especially those made with lenses

not optimized for digital cameras it may be more noticeable toward the corners of the

image, as shown in Figure 3.20

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high-light edges or to all edges

Figure 3.20 Chromatic aberration (fringing) is noticeable along the branches in this image, when viewed at 100–200%

magnification, but you can easily remove it by adjusting the Chromatic Aberration sliders

before using these sliders, it’s a good idea to zoom in to 200% or more to easily see the fringing and the results of moving the sliders holding down Alt/option while

dragging these sliders limits which color channels are visible and makes it significantly

easier to locate the best setting for each slider

Vignetting is darkening in the corners of your images it typically occurs when

a lens originally designed for 35mm film photography, and not optimized for digital

cameras’ sensors, is used with a digital camera that has a sensor that is smaller than the

film area would have been however, vignetting also sometimes results when using a

lens hood with wide-angle lenses or even from using filters with wide-angle lenses The

Vignetting controls enable you to reduce or eliminate the darkening in the corners:

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applied to the corners

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on the midpoint slider increase the area that is affected, while smaller numbers reduce it

make adjustments in small increments while closely watching the effect on your image

Adding Grain and Vignetting: The Effects Tab

Post Crop Vignette as shown in Figure 3.21

Figure 3.21 In CS5 it’s possible to add grain as well

as several types of artistic vignettes

with digital photography, some people miss the grain that was characteristic of various types of film There are three sliders to use to add grain to an image The first slider controls the amount of grain to add, the second the size of the grain, and the third the texture of the grain The best way to get a feel for these sliders is to adjust them to their extreme settings, then adjust them visually to achieve the desired results

The Post Crop Vignetting controls enable you to add a vignette, either dark or light, after cropping an image There are three styles to choose from the drop-down menu highlight Priority applies the vignette while trying to maintain the natural highlights as much as possible, rather than uniformly darkening (or lightening) every-thing This tends to make the edges look “burned in.” however, it’s possible that there can be some color shifts in the darkened areas Color Priority tries to maintain as much of the color fidelity as possible while darkening just the edges in some ways the effect looks like a less opaque layer or black on the edges over the color some people find it dulls the appearance of the photo Paint overlay is similar to the basic Vignette tool on the Lens Correction tab but can be applied to a cropped image You may want

to try the various effects to see which is best for a particular image, but we often find that highlight Priority gives the best results

in addition to the Amount and midpoint sliders, you can control the shape of the vignette with the roundness slider, and control how gradually the vignette blends

into the image with the Feather slider The highlights slider is enabled only with

the highlight Priority and the Color Priority styles Use it to apply less vignetting to

strong highlights The best way to get comfortable using these sliders is to experiment

by setting the Amount very high so the effect is easy to see Then adjust the other

slid-ers Finally, back off the Amount until you achieve the desired effect

Accounting for Camera Variation: The Camera Calibration Tab

raw information from your camera The default is now Process 2010 and is what you

should use most of the time Adobe claims that among other tweaks, the processing

of some reds and yellows has been noticeably improved earlier versions of ACr used

Process 2003, and this option appears as an option for legacy reasons for use with

images previously processed in ACr

The Camera Profile drop-down menu contains a variety of presets that yield slightly different interpretations of your images These profiles differ according to

your specific camera model The algorithms used in each vary slightly so that some

have more contrast, some more saturation, etc we suggest you experiment with the

presets and choose the one that results in an initial image appearance closest to your

personal style This profile setting is sticky, meaning that whatever profile you choose

will be used for other images unless you specifically change it

most nature photographers never touch the remaining sliders; those who do will need to use them only rarely The purpose of the these sliders is to tweak the performance

of the built-in camera profiles to account for any variations between your camera and the

one they actually used to build the profiles in ACr for that specific camera model if you

notice that your images routinely have a slight color cast, rather than removing it in the

Adjust tab, you can use the sliders here to set a correction To do this accurately, you need

to shoot a color-checker chart, such as those available from X-rite (www.xrite.com), and

then compare it to a downloaded version with known values You then move the sliders

to match up the colors To modify the reds, use the controls in the red Primary section;

to adjust the greens, use the ones found in the green Primary section; and to adjust the

blues, use the sliders found in the blue Primary section You can also adjust the tint of the

shadows

After creating settings for a particular camera, save them as the Camera raw defaults by using the fly-out menu as described earlier in this chapter Then go to the

toolbar in ACr, and click the Preferences icon to access the Preferences dialog box

Check the option make defaults specific to Camera serial number That way, if you

have several cameras, ACr will use the correct camera calibrations for each one

Preset Tab

to the right of the name of the tab and choose save settings That way, you can use

the same settings on other images by choosing the particular preset

Snapshot Tab

it’s now possible to create and save multiple versions of an image For example, you could create a black-and-white version as well as a color version or one with a very different crop, etc when you have adjusted the image in a way that you’d like to keep,

image looking this way That way you can further modify the image any way that you like To return the image to the snapshot, open the snapshot tab and click the snap-shot or choose Apply snapsnap-shot from the fly-out menu at the top right of the tab and choose the desired snapshot To delete a snapshot, select it and then click the Trashcan icon in the lower right of the interface

You can make multiple snapshots for each image, and open each simultaneously into Photoshop This is particularly useful with very contrasty images if you want to create two versions to merge together to extend the dynamic range This way you can use the raw file to access highlight or shadow information that may not be accessible

in the converted image that hdr Toning uses (we cover single-image hdr Toning in Chapter 8, “Composites.”)

Making Localized Adjustments

ACr includes the ability to make localized adjustments right in the raw converter

This means that you can make adjustments to specific parts of your image while still accessing all the information your sensor captured rather than having to wait and use the converted file in Photoshop with selections and layer masks it’s worth spending the time to get comfortable with these new tools At first they may seem a bit quirky, but if you follow our instructions, you’ll have them under control in no time!

Using the Adjustment Brush

when you click the Adjustment brush icon, the interface changes, as shown in Fig-ure 3.22 The first controls consist of three radio buttons that let you specify whether you’re making a new adjustment, adding to or modifying an existing adjustment, or erasing part of an adjustment every time you use a new Adjustment brush on the image,

show Pins in the lower-left part of the interface To remove a pin, click on it and press delete

Lower in the interface are sliders to control the features of each brush size refers to the size of the brush, and Feather controls whether the edges of the adjust-ment blend in gradually to the image or have a discrete edge Flow controls the rate the correction is applied or, in other words, how rapidly the effect flows out of the brush density refers to the opacity of the effect