Adobe Photoshop CS4 for Photographers phần 6 pptx

329 Image editing essentials Chapter 5 Multiple adjustment layers When you add multiple adjustment layers you can preview how the image will look using various combinations of adjustment layers and readjust the settings as many times as you want before applying them permanently to the photo. For example, you might want to use multiple adjustment layers to apply different coloring treatments to a picture. Instead of producing three versions of an image, all you need to do is add three adjustment layers, each using a different coloring adjustment, and switch the adjustment layer visibility on or off to access each of the color variations (Saving Layer Comps can help here). While it is possible to keep adding more adjustment layers to an image, you should try to avoid any unnecessary duplication of the layers. It is wrong to assume that when the image is fl attened the cumulative adjustments will somehow merge to become a single image adjustment. When you merge down a series of adjustment layers, Photoshop will apply them sequentially, the same as if you had made a series of normal image adjustments. So the main thing to watch out for is any doubling up of the adjustment layers. If you fi nd you have a Curves adjustment layer above a Levels adjustment layer, it would be better to try and combine the Levels adjustment within the Curves adjustment instead. Of course, when you use masked adjustment layers to adjust specifi c areas of a picture you can easily end up with lots of adjustment layers. One potential drawback of this is that it may slow down the screen preview times. This slowness is not a RAM memory issue, but to do with the extra calculations that are required to redraw the pixels on the screen. If you think this is happening then try switching off some of the adjustment layers while you are editing the photograph. To summarize, the chief advantages of adjustment layers are: the ability to defer image adjustment processing, and the ability to edit the layers and make selective image adjustments. Figure 5.54 This shows an example of how adjustments can be grouped together and a single mask applied to the combined group of layers. Grouped adjustments If you place your image adjustment layers inside a layer group you can use the layer group visibility to turn multiple image adjustments on or off at once (see Figure 5.54). You can also add a layer mask to a layer group and use this to hide or show all the adjustments in a group. Fi gu re 5 .5 4 Th is s ho ws a n ex am pl e of h ow Repeated adjustments warning It is important to stress here that the pixel data in an image can easily become degraded through repeated image adjustments. Pixel data information will progressively become lost through successive adjustments as the pixel values are rounded off. This is one reason why it is better to use adjustment layers, because you can keep revising these adjustments without damaging the photograph until you fi nally decide to fl atten the image. Martin Evening Adobe Photoshop CS4 for Photographers 330 Adjustment layer masks Although there are dodge and burn tools in Photoshop, which have been improved in Photoshop CS4, they are not really suited for dodging and burning broad areas in a photograph. If you want to dodge or burn a photograph, such as darken a sky or lighten someone’s face, then the best way to do this is to use a masked adjustment layer. This is not to say that the dodge and burn tools serve no use. Even though they have been improved in CS4, they are just not ideal for this type of photographic retouching. Working with adjustment layers is by far the best way to shade or lighten portions of an image, because you have the freedom to re-edit an adjustment layer to make the adjustment lighter or darker. Adjustment layers have an active layer mask, which means that whenever an adjustment layer is active, you can paint or fi ll using black to selectively hide an adjustment effect, and paint or fi ll with white to reveal again. Plus you can also keep editing the adjustment layer mask (painting with black or white) until you are happy with the quality of the mask (see Figure 5.55). Masks panel controls The Masks panel (Figure 5.57) is also new to Photoshop CS4 and can be used to refi ne the mask or masks associated with a layer. Layer masking is a topic I’ll be discussing more fully in Chapter 9 but, because it is relevant to masking adjustment layers, I thought it best to briefl y introduce the Masks panel features here fi rst. Adjustment layers are added to the layer stack with a pixel mask attached, so the default mode for the Masks panel will show the Pixel mask mode options. If you click on the Vector mask mode button next to it, you can add and edit a vector layer mask (see Step 4 on page 333). You can tell which mode is active because it will say Pixel Mask or Vector mask at the top of the panel and the relevant mode button will have a stroked border. The Density slider can be used to adjust the density of the mask. If you apply a black mask this will normally Figure 5.55 This shows an example of a darkening adjustment layer applied to an image, but with a black to white gradient applied to the layer mask to fade out the adjustment from the middle of the image downwards. o e w ( M T C w m m in igure 5 55 This shows an example of a ‘Stalkers’ by The Wrong Size. Photograph: © Eric Richmond 331 Image editing essentials Chapter 5 Figure 5.57 The Masks panel controls. Figure 5.56 The Refi ne Edge dialog (see Chapter 9 for more information on using Refi ne Edge). hide all the black masked contents on a layer, but if you reduce the Density, this lightens the black mask color and therefore allows you to soften the contrast of the mask. So, when Density is set to 50%, the black mask colors will only apply a 50% opacity mask and the lighter mask colors will be proportionally reduced. The Feather slider can be used to soften the mask edges up to a 250 pixel radius. Beneath this though is the Mask Edge button which will open the Refi ne Edge dialog (Figure 5.56), where you’ll fi nd you have even greater control over the mask edges and softness. The Color Range button allows you to make selections based on colors that are in the image you are editing. This means that you can select colors to add or subtract from a Color Range selection and see the results applied directly as a mask. Beneath that is the Invert button for reversing a masking effect and at the bottom of the panel are options for converting a mask to a selection, deleting the mask and applying it to the layer, enabling/disabling the mask and a Delete button to remove the mask. Feather slider Convert mask to a selection Apply mask to layer Enable/disable mask Density slider Mask preview Vector mask mode Masks panel options Refi ne mask edges Make a Color Range selection Invert the mask Delete mask Pixel mask mode V R M I D M E Martin Evening Adobe Photoshop CS4 for Photographers 332 1 You can add a vignette in Photoshop by adding a darkening Levels (or Curves) adjustment, making an elliptical selection and fi lling the pixel mask with black. 2 If you go to the Masks panel you can increase the Feather amount to make the hard mask edge softer. Masks panel editing 333 Image editing essentials Chapter 5 3 But let’s say I wanted to soften the transition between the masked and unmasked areas. By decreasing the Density one can make the black areas of the mask lighter and thereby reveal more of the adjustment effect in the center of the image. 4 This technique is not just limited to pixel masks. This last step shows how I could have started with a subtractive elliptical pen path shape, applied this as a Vector mask and used the exact same Masks panel settings to soften the mask edge. Martin Evening Adobe Photoshop CS4 for Photographers 334 Color Range adjustment layer masking 1 In this example I wanted to demonstrate how to use the Masks panel controls in conjunction with an image adjustment to modify the image shown here, so that I could simultaneously control the adjustment effect and the adjustment masking. To start with, I added a new Hue/Saturation adjustment layer. I then went to the Masks panel and clicked on the Color Range button, which opened the Color Range dialog shown here. With the Localized Color Clusters option checked, I used the plus eyedropper tool to add color samples to the selection, sampling the blues in the central area of the photograph while avoiding the walls. I then adjusted the Fuzziness and Range, till I was happy with the way the selection looked, and clicked OK to the Color Range selection. 335 Image editing essentials Chapter 5 2 I then went to the Masks panel and feathered the selection, adding a 50 pixel feather. You can see a preview of the mask in both the small Masks panel preview as well as in the Layers panel. All I needed to do now was to adjust the Hue/Saturation sliders in the Adjustments panel. For this step I decided to make some of the blue colors more green and reduce the color saturation slightly. The main thing to learn from this particular example is that you can switch back and forth between the Adjustments panel and the Masks panel to re-edit the adjustment effect and masking. When you combine the ease of adjustment editing with the power of the new Masks panel and Color Range selections, Photoshop CS4 has the potential to allow you to make selections and modify images like never before. Photograph: © Eric Richmond Martin Evening Adobe Photoshop CS4 for Photographers 336 Blend mode adjustments You can lighten, darken or add contrast to an image by adding an adjustment layer above the Background layer (or at the top of the layer stack) and simply change the blend mode to Screen, Multiply or Overlay. You don’t need to apply a specifi c image adjustment, just add a neutral adjustment layer (any will do) and select one of the above layer blending modes. The Screen mode can be used to lighten an image, Multiply to darken and Overlay to add more contrast. You could achieve the same type of result by duplicating the Background layer and changing the blend mode of the duplicate layer, but this is actually quite unnecessary and you’ll end up with an image that is twice the fi le size, whereas adding an adjustment layer will normally increase the fi le size by just a few kilobytes. Blend modes are in effect a shorthand for applying different, set-value Curves adjustments. For example, the late Bruce Fraser devised a semi-automated workfl ow in which he recorded separate Photoshop actions to apply a Screen, Multiply of Overlay neutral adjustment layer and fi lled the layer mask with black. All he had to do then was select a paint brush or gradient tool to paint on the layer mask and reveal the adjustment effect. Figure 5.58 Here is the fi rst of two examples showing how you can use blend modes to adjust an image. In this example I dragged the Background layer down to the New Layer panel button to make a duplicate layer and changed the layer blending mode from Normal to Multiply. When the image was saved, the fi le size doubled to 64 MB. d l w S fi s m B Y a ( b n n t u F i g ure 5.5 8 H ere is the fi rst of two exam p les 1 This shows a photograph processed using the default Camera Raw settings. Figure 5.59 In this example I added a new Levels adjustment layer, but didn’t apply any changes to the Levels settings. I then changed the adjustment layer blend mode from Normal to Multiply. Both this and the Figure 5.58 example produced identical results, but in this case the fi le size was only increased by 57 kilobytes. 337 Image editing essentials Chapter 5 2 I started by adding a neutral adjustment layer (in this case, Levels) and changed the layer blend mode to Screen. This step lightened the whole image, but since I was mainly interested in lightening the water, I applied a linear, black to white gradient to the adjustment layer mask to fade out the adjustment from the horizon upwards. 3 I then wanted to darken the sky, so I added a second neutral adjustment layer. At this stag e I could have used a Multipl y blend mode to darken the image, but instead, I used the Overlay blend mode to apply more contrast. Again, I used the gradient tool to add a linear, black to white gradient to fade out the adjustment, this time from the horizon downwards. Overlay alternatives Instead of using the Overlay blend mode, you might also like to try using the Soft Light or Hard Light blend modes for gentler or stronger contrast adjustments. Martin Evening Adobe Photoshop CS4 for Photographers 338 Cropping The image you are editing will most likely require some kind of crop, either to remove unwanted edges or to focus more attention on the subject. Select the crop tool from the Tools panel and drag to defi ne the area to be cropped. To zoom in on the image as you make the crop, you may sometimes fi nd it useful to use the zoom tool shortcut: hold down the Spacebar followed by the C L key and marquee drag over the area you want to magnify, and to zoom out use the Spacebar plus O A or use C0 L0 (which is the shortcut for View ➯ Fit To Window). You can then zoom back in again to magnify another corner of the image to adjust the crop handles. If the crop tool does not behave as expected try clicking on the Clear button in the tool Options bar and this will reset the tool. In the normal default mode the crop tool will allow you to set any rectangular-shaped crop you like and merely trim away the unwanted pixels without changing the image size or resolution. Figures 5.60 and 5.61 show and explain the normal and modal states for the crop tool options. Crop tool presets Swap height and width Crop resolution Load foreground image dimensions and resolution Clear crop settings Front Image cropping If you want a crop to match the dimensions and resolution of a document that is already open in Photoshop, click on that document to make it active. Then click on the Front Image button in the Crop Options bar. This will load the document dimensions and resolution into the Crop Options settings. Now select the image you wish to crop and, as you drag with the crop tool, the aspect ratio of the front image will be applied. When you OK the crop, the image size will be adjusted to match the front image resolution. Figure 5.60 Here are the primary options for the crop tool. If you mouse down on the triangle button next to the crop tool you will see a list of any preloaded crop tool presets. If none are visible click on the triangle button (circled), or go to the Tool Presets panel to load the Crop and Marquee.tpl preset. New individual custom presets can be added by clicking on the New Preset button in the Tool Presets panel (circled). To set a custom crop, enter the crop unit dimensions in the Width and Height boxes followed by: mm, cm, in or px to denote the unit dimension type. In this example the crop tool has been set to a fi xed crop of 8 inches wide by 10 inches tall at a resolution of 300 pixels per inch. If you click on the button between the Width and Height boxes, you can swap these dimensions. Clicking on the Clear button clears the current crop options. [...]... identical results, but with less hassle (Figure 6. 6) Figure 6. 6 These two screen shots show a Split Tone being applied to a full color image In the top screen shot you can see the before version and in the bottom screen shot you can see the result after applying a blue/sepia Split Toning effect Photograph: © Eric Richmond 361 Martin Evening Adobe Photoshop CS4 for Photographers Advanced B&W Photo tips There... crop tool, or by making an angle measurement with the measure tool followed by an arbitrary rotation as described in Figure 5 .66 Figure 5 .65 The Image ➯ Rotate menu including the Arbitrary option which is described below in Figure 5 .66 Figure 5 .66 When an image is opened up in Photoshop, you may discover that it is not perfectly aligned Although the crop tool will allow you to both crop and rotate at... image, the masked figure started to disappear As before, it is important to watch carefully for jagged edges and not compress the image too much As you can see, this technique doesn’t completely remove all the pixels, but this edited image could easily be tidied up using the healing brush Photograph: © Jo Cowler 2003 347 Martin Evening Adobe Photoshop CS4 for Photographers Background layers and big data... Martin Evening Adobe Photoshop CS4 for Photographers Black and white film conversions Traditional black and white film emulsions can all differ slightly in the way they respond to different portions of the visual spectrum (as well as the colors we can’t see) This is partly what gives emulsion films their ‘signature’ qualities So in a way, you could say that film also uses standard formulas for converting... Collinge Model: Jagna Szaykowska @ Profile 357 Martin Evening Adobe Photoshop CS4 for Photographers The extra color sliders Camera Raw has more sliders than the Black & White adjustment and these allow you to adjust the in-between color ranges such as Oranges, Aquas and Purples The Oranges slider is useful for targeting skin tones and the Aquas is useful for adjusting photographs of sunny beach scenes Having... completely and still be able to drag the corners or sides of the crop to make adjustments 339 Martin Evening Adobe Photoshop CS4 for Photographers Shade cropped area Shade color Enable perspective cropping Shade opacity Apply crop Cancel crop Figure 5 .61 After you have dragged with the crop tool and before you commit to a crop, the tool Options bar will change (as shown here) to what is known as a modal... Contrast’ preset and the saved presets can be accessed by mousing down on the presets menu at the top of the adjustments panel (circled) Figure 6. 3 Examples of different Black & White Adjustment presets applied to a color image 353 Martin Evening Adobe Photoshop CS4 for Photographers Color blend mode You will notice that I suggest you use the Color blend mode when applying adjustment layers that are intended... clicked on the Highlights button and added a yellow cast to the highlights I also set the adjustment layer blending mode to Color, which helped to preserve the image luminance information 355 Martin Evening Adobe Photoshop CS4 for Photographers Curves adjustment layer split toning The Color Balance method is reasonably versatile, but you can also colorize a photograph by using two Curves adjustment layers... current image size Figure 5 .68 To use the crop tool as a canvas size tool, first make a full frame crop, release the mouse and then drag any one of the bounding box handles outside of the image and into the canvas area Double-click inside the bounding box area or hit E to add to the canvas size, filling with the background color 343 Martin Evening Adobe Photoshop CS4 for Photographers Edge detection... panel like this in Photoshop Figure 6. 5 Here is an example of the Split Toning panel in action 360 Chapter 6 Black and white Camera Raw color image split toning Although the Split Toning panel appears to be an extension of the HSL Grayscale panel, the Split Toning controls are just as useful for working on color images Although there are ways to produce a color cross-processing effect in Photoshop, the . selections, Photoshop CS4 has the potential to allow you to make selections and modify images like never before. Photograph: © Eric Richmond Martin Evening Adobe Photoshop CS4 for Photographers 3 36 . image. Martin Evening Adobe Photoshop CS4 for Photographers 330 Adjustment layer masks Although there are dodge and burn tools in Photoshop, which have been improved in Photoshop CS4, they are not. the instructions in Figure 5 .68 below). Martin Evening Adobe Photoshop CS4 for Photographers 344 Content-Aware Scaling This is probably the star feature of Photoshop CS4, yet also the most controversial