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.Figure 11-4 shows off four of theeffects at 230 ppi.To create Figure 11-5, I applied the Mezzotint filter set to the Long Lines effect.ThenI used the Edit ª' Fade Mezzotint command to mix filtered and original images.Iselected Overlay from the Mode pop-up menu and set the Opacity value to 40 per-cent.The result is a scraped image.(I ve decreased the resolution of the image to180 ppi so that you can see the effect a little more clearly.)When applied to grayscale artwork, the Mezzotint filter always results in a black-and-white image.When applied to a color image, the filter automatically applies theselected effect independently to each of the color channels.Although all pixels ineach channel are changed to either black or white, you can see a total of eight col-ors  black, red, green, blue, yellow, cyan, magenta, and white  in the RGB com-posite view.The upper-left example of Color Plate 11-3 shows an image subject tothe Mezzotint filter in the RGB mode.If the Mezzotint filter affects each channel independently, it follows that the colormode in which you work dramatically affects the performance of the filter.Forexample, if you apply Mezzotint in the Lab mode, you again whittle the colors downto eight, but a very different eight  black, cyan, magenta, green, red, two muddyblues, and a muddy rose  as shown in the top-middle example of Color Plate 11-3.If you re looking for bright happy colors, don t apply Mezzotint in the Lab mode. Part III &' Selections, Masks, and Filters496Medium dots Coarse dotsShort lines Long linesFigure 11-4: The results of applying the Mezzotint filter set to each of fourrepresentative effects.These line patterns are on par with the halftoning optionsoffered when you select Mode ª' Bitmap, as discussed back in Chapter 4. Chapter 11 &' Full-Court Filtering497Figure 11-5: To get this effect, I applied the Mezzotintfilter and then chose the Fade command (on the Editmenu in Photoshop 6).In the Fade dialog box, Iselected the Overlay mode and set the Opacityvalue to 40 percent.In CMYK, the filter produces roughly the same eight colors that you get in RGB white, cyan, magenta, yellow, violet-blue, red, deep green, and black.However, asshown in the top-right example of the color plate, the distribution of the colors ismuch different.The image appears much lighter and more colorful than its RGBcounterpart.This happens because the filter has a lot of black to work with in theRGB mode but very little  just that in the black channel  in the CMYK mode.The bottom row of Color Plate 11-3 shows the effects of the Mezzotint filter afterusing the Fade command to mix it with the original image.As in Figure 11-4, I choseOverlay from the Mode pop-up menu and set the Opacity value to 40 percent.Thesethree very different images were all created using the same filter set to the sameeffect.The only difference is color mode. Part III &' Selections, Masks, and Filters498Edge-Enhancement FiltersThe Filter ª' Stylize submenu offers access to a triad of filters that enhance theedges in an image.The most popular of these is undoubtedly Emboss, which addsdimension to an image by making it look as if it were carved in relief.The other two,Find Edges and Trace Contour, are less commonly applied but every bit as capableand deserving of your attention.Embossing an imageThe Emboss filter works by searching for high-contrast edges (just like the SharpenEdge and High Pass filters), highlighting the edges with black or white pixels, andthen coloring the low-contrast portions with medium gray.When you chooseFilter ª' Stylize ª' Emboss, Photoshop displays the Emboss dialog box shown inFigure 11-6.The dialog box offers three options:&' Angle: The value in this option box determines the angle at which Photoshoplights the image in relief.For example, if you enter a value of 90 degrees, youlight the relief from the bottom straight upward.The white pixels thereforeappear on the bottom sides of the edges, and the black pixels appear on thetop sides.Figure 11-7 shows eight reliefs lit from different angles.I positionedthe images so that they appear lit from a single source.Figure 11-6: The Emboss dialog box lets youcontrol the depth of the filtered image and theangle from which it is lit. Chapter 11 &' Full-Court Filtering499135 90 45180 0 135  90  45Figure 11-7: Reliefs lit from eight different angles, in45-degree increments.In all cases, the central sun imageindicates the location of the light source.Height and Amountvalues of 1 pixel and 250 percent were used for all images.&' Height: The Emboss filter accomplishes its highlighting effect by displacingone copy of an image relative to another.Using the Height option, you specifythe distance between the copies, which can vary from 1 to 10 pixels.Lowervalues produce crisp effects, as demonstrated in Figure 11-8.Values above3 goop up things pretty good unless you also enter a high Amount value.Together, the Height and Amount values determine the depth of the imagein relief.TipThe Height value is analogous to the Radius value in the Unsharp Mask dialogbox.You should therefore set the value according to the resolution of yourimage  1 for 150 ppi, 2 for 300 ppi, and so on. Part III &' Selections, Masks, and Filters5001, 50% 3, 50% 5, 50%1, 200% 3, 200% 5, 200%1, 500% 3, 500% 5, 500%Figure 11-8: Examples of different Height settings (first value)and Amount settings (second value).The Angle value usedfor each image was 135 degrees.&' Amount: Enter a value between 1 and 500 percent to determine the amount ofblack and white assigned to pixels along the edges.Values of 50 percent andlower produce almost entirely gray images, as you can see in the top row ofFigure 11-8.Higher values produce sharper edges, as if the relief were carvedmore deeply.As a stand-alone effect, Emboss is only so-so.It s one of those filters that makes yougasp with delight the first time you see it but never quite lends itself to any practi-cal application after you become acquainted with Photoshop.But if you think ofEmboss as an extension of the High Pass filter, it takes on new meaning.You can use Chapter 11 &' Full-Court Filtering501it to edit selection outlines in the quick mask mode, just as you might use the HighPass filter.You also can use it to draw out detail in an image.Figure 11-9 shows the result of using the Fade command immediately after applyingthe Emboss filter.(Remember, Fade now resides on the Edit menu, not the Filtermenu.) First, I applied the Emboss filter at an Angle of 135 degrees, a Height of 2 pix-els, and an Amount of 250 percent.Then I pressed Ctrl+Shift+F to display the Fadedialog box.To create the left example, I selected Darken from the Mode pop-up menu.This added shadows to the edges of the image, thus boosting the texture withoutunduly upsetting the original brightness values.I selected the Lighten blend modeto create the right example.In both cases, I set the Opacity value to 70 percent.Figure 11-9: After applying the Emboss filter, I used my old friend the Fadecommand to darken (left) and lighten (right) the image.TipTo create a color relief effect, apply the Emboss filter and then select the Luminosityoption in the Fade dialog box.This retains the colors from the original image whileapplying the lightness and darkness of the pixels from the filtered selection.Theeffect looks something like an inked lithographic plate, with steel grays and vividcolors mixing together.An example of this effect at 80 percent Opacity appears inthe first example of Color Plate 11-4.The second example in that same color plate shows a more impressive  if lesspractical  technique [ Pobierz caÅ‚ość w formacie PDF ]

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