Hướng dẫn sử dụng Coreldraw x5 - part 72 ppsx

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Hướng dẫn sử dụng Coreldraw x5 - part 72 ppsx

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● Glows All effects created with the Drop Shadow tool are dynamically updated bitmaps, and as such they can look soft as shadows do on overcast days; they can also be put into merge modes. Therefore, you take a blurry bitmap, put it in Multiply merge mode, and you have a re-creation of a shadow. However, if you take that same blurry bitmap, give it a light color, and then put it in Normal or Add merge mode, you have a glow effect. This is part of what CorelDRAW does when you use a Glow preset, and you have a lot of manual control for creating a shady or glowing look that perfectly suits a piece of work. Like other effects in CorelDRAW, drop shadows maintain a dynamic link; any changes to the control object automatically update the shadow. A shadow’s look—its position, color, opacity, and feathering—can be customized, plus you can manipulate the angle, stretch, and fade properties of shadows and glows. Using the Drop Shadow Tool and Property Bar The Drop Shadow tool is about as hard to use as click-dragging, and after you click-drag to create a custom shadow, you’ll see a series of property bar options. The tool is found in the toolbox with other interactive tools. A drop shadow effect is anchored to an object at a specific point. For example, after you click-drag to create a drop shadow, the shadow is apparently anchored to the object by the white marker, the beginning of the effect. However, if you drag to any of the other three sides of an object, the shadow will snap to these other areas. Shadows are anchored because you probably don’t want your drop shadow to become detached from your object if you move the object. Losing your shadow is a privile ge only to be enjoyed by vampires. After an initial click-drag to add a drop shadow to an object, you’ll notice the property bar lights up, and you now have a ton of options for refining what amounts to sort of a “default” drop shadow effect. Drop shadows can take one of two states: flat (drop) or perspective (cast). Depending on which state you use, the property bar options will change. Figure 22-12 handsomely illustrates a look at the property bar when applying a flat shadow. Here’s an introduction to shadow-making through a tutorial intended to familiarize you with the property bar options as well as with a little interactive editing. As with most of the effects in CorelDRAW, the onscreen markers for click-dragging to customize a shadow are very much like the markers for the Extrude fountain fill and other tool control handles. 694 CorelDRAW X5 The Official Guide Working the Property Bar and Shadow-Making Markers 1. Create an interesting object to which you want to apply a shadow, and finish applying its fill and outline properties. If you deselect it, this is okay—click the object with the Drop Shadow tool to select it. 2. Choose the Drop Shadow tool, and notice that your cursor changes to resemble the Pick tool with a tiny drop shadow icon in its corner. If you don’t do anything with the tool, the only option on the property bar is the Preset drop-down list at the moment. 3. Click-drag from roughly the center of the selected object; continue holding down the mouse button so you can see some of the mechanics of this effect. Notice that a preview outline appears that matches your object. This indicates the position of the new shadow once you release the mouse button. Notice also that a white marker has appeared in the center of the object, and that another marker has appeared under the cursor as you drag it. A slider control has also appeared at the midpoint of a dotted guideline joining the two markers. CHAPTER 22: Lens Effects, Transparency, Shadows, Glows, and Bevels 695 22 FIGURE 22-12 You might be a shadow of your former self after sifting through all the drop shadow options! Drop Shadow tool Preset List Drop Shadow Angle Drop Shadow Opacity Shadow Feathering Shadow Fade Shadow Stretch Shadow Color Drop Shadow Offset Position Feathering Direction Feathering Edge Copy Shadow Properties Clear Drop Shadow 4. Release the mouse button and boing!—a drop shadow appears. This is a default shadow, colored black, and it has default properties. 5. Drag the slider control on the guideline between the two square-shaped markers toward the center of your original object. This reduces the shadow’s opacity, making it appear lighter and allowing the page background color—and any underlying objects—to become more visible. 6. To change the shadow color, click the color selector on the property bar and then select a color. Notice that the color is applied; you can do some wild stage-lighting stuff by choosing a bright color for the shadow, but the opacity of the shadow remains the same. 7. Drag the white marker to the edge of one side of the original object. Notice the shadow changes shape, and the marker snaps to the edge. This action changes a drop shadow to a perspective shadow. 8. Using property bar options, change the default Shadow Feathering value to 4, and then press ENTER. The shadow edges are now more defined. Increase this value to a setting of 35, and notice that the shadow edges become blurry; you’ve gone from a sunny day shadow to an overcast day shadow. 9. Click the Shadow Fade slider control and increase it to 80. Notice that the shadow now features a graduated color effect, with the darkest point closest to the original object becoming a lighter color as the effect progresses farther away from your object. This is not only a photorealistic touch, but it also helps visually integrate a shadow into a scene containing several objects. If the Shadow Fade slider is dimmed, it’s because you didn’t complete step 7 successfully. The Shadow Fade slider is only available when the shadow type is a perspective shadow. 10. Click the Shadow Stretch slider and increase it to 80. The shadow stretches farther in the direction of the interactive marker, and you’ve gone from high noon to almost dusk in only one step. 11. Click a blank space on the page to deselect the effect, or choose the Pick tool, and you’re done. Take a break and hang out in the shade for a while. To launch quickly into the editing state of an existing drop shadow effect while using the Pick tool, click the shadow once to display property bar options, or double-click the shadow to make the Drop Shadow tool the current tool. Manually Adjusting a Drop Shadow Effect After the drop shadow effect is applied, you’ll notice the interactive markers that appear around your object. You’ll see a combination offset position and color marker joined by a 696 CorelDRAW X5 The Official Guide dotted line featuring an Opacity slider. If you’re new to interactive controls, this illustration identifies these markers and indicates their functions. Ill 22-11 Shadows as Glow Effects CorelDRAW’s drop shadow effect is not limited to making shadows; if you think about it, a blurry bitmap can also represent a glow effect by using a different merge mode and color. By default, whenever a new shadow is created, black is automatically the applied color. You can reverse this effect by applying light-colored shadows to dark-colored objects arranged on a dark page background or in front of a darker-colored object. Here you can see a black compound path (the cartoon light bulb) on top of a Radial fountain-filled rectangle (black is the end color and 30% black is the start color at center) with a light-colored shadow effect applied. The result is a credible glow effect; there are also Glow Presets on the property bar when you use the Drop Shadow tool to give you a jumpstart on creating glows. Ill 22-12 CHAPTER 22: Lens Effects, Transparency, Shadows, Glows, and Bevels 697 22 Position marker Position marker Opacity slider (50%) Offset/Color marker (black) Offset/Color marker (40% black) Opacity slider (80%) Glow Background fountain fill rectangle, Radial style This chapter has shown a lot of non-special effects; effects that aren’t supposed to “wow” your audience, but rather shadows, lens effects, transparency, and bevels speak of a quiet elegance that strikes the viewer on a subliminal level. It’s well worth your time to become proficient with these effects for when you need a touch of photorealism in a drawing, something that strikes the audience without hitting them over the head. This concludes the special effects portion of The Official Guide, and if you turn the page, you’ll be entering an arena of graphics that look so real, they’re picture-perfect. You’re going to get into digital imagery and what CorelDRAW and Corel PHOTO-PAINT offer in the way of photo retouching features. Bring along a snapshot of the kids. 698 CorelDRAW X5 The Official Guide PART VIII The Bitmap Side of Corel Graphics Suite This page intentionally left blank CHAPTER 23 Bitmap Boot Camp: Working with Photographs 701 A time will come when you’ll want to set aside the Bézier pen tool and the fountain fill—your layout for a brochure, for example, is all done, and now you want to add a photograph of your product, front page and center. The good news is that CorelDRAW can import just about any bitmap file you have. A photo from your camera, a scan of a photo, a painting you created in PHOTO-PAINT, or an image you snagged off your client’s website—you can crop, rotate, and perform enhancements on it right within CorelDRAW. This chapter takes you first through the structure of pixel-based images (bitmaps): how you can get them to print well, what you can and cannot do with them, special properties, and the difference between this type of graphic and the one you’re more accustomed to: vector artwork. Then you’ll work with some photographed and created bitmap images to learn how to do some basic—and some fairly advanced—image editing and enhancing. Putting a photo into a CorelDRAW document isn’t very rewarding unless it’s a really good photo, and you feel confident it will print well. This chapter delivers the goods on the whats, whys, and whens for bitmap importing, finessing, and integration to make your documents come alive and communicate. Download and extract all the files from the Chapter23.zip archive to follow the tutorials in this chapter. The Properties of a Pixel-Based Image Many of us take the structure of a pixel-based image for granted, without a lot of concern over its structure. We take a photograph with our megapixel camera, we copy the image to hard disk as a JPEG, we email it, and that’s the end of the story. However, if you want to do something with a digital image, such as incorporate it into a flyer, crop it, resize it, or put something else into it within a CorelDRAW composition, this is only the beginning of the story of pixel-based images and their manipulation. Without a cursory understanding of how pixel-based images are structured, you won’t be able to successfully do as many things as you’d like to with them in CorelDRAW. Therefore, the following sections dig a little into what goes into a pixel-based image, so you can get more out of them as covered in the rest of this chapter. Pixel Artwork vs. Vector Artwork Although there are two fundamentally different types of graphics you can work with on a personal computer—vector graphics and pixel graphics—actually 100 percent of what you see onscreen is a pixel-based graphic. Your computer monitor has no easy way to display vectors as vectors, so even when you work with paths in CorelDRAW, what you’re seeing onscreen is a pixel-based representation that CorelDRAW draws to your screen on-the-fly. This truth is not offered to make your life harder, but rather to get you thinking more about pixels as an art form and as a tool. 702 CorelDRAW X5 The Official Guide Vector artwork, the kind of art you create in CorelDRAW, is resolution independent, a term you’ll hear a lot, particularly if you’re around programmers. Resolution independent means that the art you create in CorelDRAW can be scaled up and down, rotated and distorted every which way, and it still retains focus and its structural integrity. Vector artwork can be boiled down to a direction a path travels in, the width of its outline, its fill color—regardless of how complex you make a drawing, it can be explained and saved to file in math terms. And because math can be divided and multiplied without discarding the values you put into an equation, you understand that scaling a vector drawing doesn’t change its core values. For example, 150 × 2 = 300 is an equation that results in twice the 150 value, but the 150 value isn’t really altered to produce a result of 300. Pixel-based graphics, on the other hand, are resolution dependent. This means that a finite number of pixels goes into what you see onscreen, and it cannot be increased or decreased without making a visible, fundamental change to the structure of such a graphic. Pixel-based images aren’t usually as flexible as vector artwork; until you understand the term resolution, it’s quite possible to irrevocably damage a pixel-based image, throwing it out of focus or adding artifacting (explained in a moment). However, the positives of pixel images outweigh any negatives: while it’s very easy to take a snapshot, it’s quite hard to draw (using vectors) something that looks exactly like a photograph. Pixel-based images can have depth of field, exposure, a source of scene lighting, and other properties; although many talented artists have created CorelDRAW pieces that look almost like a photograph, CHAPTER 23: Bitmap Boot Camp: Working with Photographs 703 23 Artifacts and Anti-Aliasing It’s possible to take resolution-dependent bitmap images and make them larger, artificially increasing the size (and the saved file size) of the final image. However, you cannot add detail to an existing photograph by enlarging it: when a computer application is commanded to add pixels to an image, it has no real way of telling what color pixels should be added to the photograph. Not CorelDRAW, not Adobe Photoshop—no application (except those phony forensic computers you see on TV shows) can intelligently, artistically, or accurately add, for example, detail to a photo of a mailbox so the address instantly becomes crisp and legible. What you get when you perform any “make this photo larger” command is “fake resolution”; the program averages pixel colors neighboring the original pixels to create more, similarly colored pixels. This can often lead to artifacting, what we commonly describe as “there’s some junk in the upper left of this photo near my aunt’s face.” Artifacting can be introduced to a digital photograph at any stage of photography: your camera didn’t write the file correctly, the image became corrupted when you copied it to your hard drive, and/or you tried to enlarge a resolution-dependent image. The cure for the last reason here is, don’t resample important images; instead, print a copy of the image at its original size and see how it looks. From there, increase its . picture-perfect. You’re going to get into digital imagery and what CorelDRAW and Corel PHOTO-PAINT offer in the way of photo retouching features. Bring along a snapshot of the kids. 698 CorelDRAW X5. that CorelDRAW draws to your screen on-the-fly. This truth is not offered to make your life harder, but rather to get you thinking more about pixels as an art form and as a tool. 702 CorelDRAW X5. the effects in CorelDRAW, the onscreen markers for click-dragging to customize a shadow are very much like the markers for the Extrude fountain fill and other tool control handles. 694 CorelDRAW X5 The

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