Hướng dẫn sử dụng Coreldraw x5 - part 89 pps

Ill 27-6 Here’s what the options in this dialog control: ● Screening Technology This selector drop-down contains scripts for specific printing technologies such as Agfa and Linotronic image-setting devices. When Standard Defaults is used as the Screening Technology, other options are set according to settings for your specific printer driver, accessed through Properties on the General tab. ● Resolution This displays the output resolution of your printed material, the default value of which is set according to the Screening Technology selected. A service bureau or your print vendor will know the specifics. ● Basic Screen This option sets the resolution as measured in lines per inch of the screens rendered in your output material. Check with your print vendor for the exact setting needed. If you need to adjust this value, various choices will appear depending upon which Screening Technology and image setter Resolution is currently selected. The options shown in the Basic Screen section will also be available back in the Separations main tab. ● Halftone Type The Halftone Type selector is used to set the shape of the actual dots that compose the screens in the final output. Using this drop-down menu, you can choose to use such shapes as the Default (Dot), Line, Diamond, Elliptical, Euclidean, Lines, Grid, Microwaves, Rhomboid, and Star. If you’re just getting into commercial printing, anything other than a dot halftone shape is used either because the print press pulls better prints, or because you really know what you’re doing and want to create an effect in the finished print job. Microwaves, for example, is a special effect that sounds interesting, but you would need to have already seen the 864 CorelDRAW X5 The Official Guide effect on a printed sample before choosing it, and then you would do a short run to see whether the example produces the same effect in your own piece. On the other hand, Elliptical and Star shapes can be used to sharpen the output of a print, and therefore are more of an enhancer than an effect. Setting Trapping Options Trapping involves either spreading or overprinting portions of colored objects to avoid printing inaccuracies, the most common one being paper white showing at the edge between two color objects. Overprinting causes one ink color to print over another, resulting in two layers of ink— it’s a technique used to work around imprecise ink alignment. You can set the overprinting of fills and outlines applied to objects directly in your document; you cancel out of the Print dialog and return to the open document. Then with the Pick tool, right-click one or more objects, and choose Overprint Fill or Overprint Outline from the pop-up menu options. Overprinting can be set in three ways: directly in your document for each object, in the Separations tab using either fill or outline ink overprinting options, or using automated trapping. Where options have been set manually in your document or for each ink color, overprinting operates on a three-level hierarchy, which creates a condition where one overprinting setting overrides another one, as follows: 1. When printing, the objects in the drawing are first examined for any selected fill and/ or outline overprinting properties. Applying overprint properties directly to an object in a drawing overrides all other overprinting functions. 2. Next, ink color overprinting options are examined. If an ink color is set to overprint and no object fill or outline overprint properties are applied, the ink color overprints the objects beneath it. 3. Finally, the trapping options you have chosen in the Separations tab of the Print dialog are examined. If no overprint options are set, then automatic trapping will be applied if either Auto-spreading or Fixed Width is selected. Automatic trapping and overprinting options in the Separations tab have the following effects on how colors in your document are printed: ● Preserve Document Overprints This option preserves the overprint options applied directly to your drawing objects, regardless of the settings selected elsewhere. Your other option (on the drop-down list), Ignore, lets you work with the settings in the Separations tab, and any custom overprinting you’ve applied directly to objects in your document is ignored. ● Always Overprint Black When this option is selected, all objects that have color tints between 95 and 100 percent black will overprint underlying ink colors. Usually, you want black to overprint; black is the key plate for all the fine details, particularly necessary if you’re using a bitmap image in part of your design. CHAPTER 27: Printing: Professional Output 865 27 ● Auto-spreading This option causes CorelDRAW’s print engine automatically to create an overprinting outline of identical ink color around objects where they overlap other ink colors. When the option is selected, you can set the Maximum width of the spread within a range of 0 to 10 points (0.5 point is the default, a little wider than a hairline). Automatic width values vary according to the difference between the color being overprinted and the underlying color. Choose Fixed Width to set the Auto-spreading width of the outline to a constant width regardless of this color difference. When Auto-spreading is selected, choosing the Text Above option makes CorelDRAW ignore text sizes below a certain size; small text is often distorted by the spread effect. Choose a size between 0 and 200 points; the default is 18 points. In-RIP Trapping Settings If your output device is equipped with its own In-RIP trapping software, you can use this option. The term RIP stands for raster image processor, the process of converting mathematical chunks of information to a map of where dots of ink go on the page to represent what you see onscreen. Many high-end image setters are equipped with internal software with which certain In-RIP trapping makes the whole trapping process faster and more efficient. This option is dimmed unless the output device defined on the General tab is PostScript compatible, PostScript 3 is selected in the Compatibility area of the PostScript tab, and Print Separations is disabled in the Color tab. With the feature enabled, choose the In-RIP Trapping option, and then click the Settings button to open the In-RIP Trapping Settings dialog, shown in Figure 27-4. Here you’ll find an ink listing similar to the one in the Separations tab, plus other options for setting these items: ● Neutral Density This is a value based upon the relative darkness of each process ink, ranging from 0.001 to 10.000. Trapping software derives neutral density for spot colors based upon their CMYK equivalents. Default values often work, or the value can be set according to advice from your print vendor. Most third-party ink swatches list the neutral density values for each ink color. ● Type You choose the Type for an individual ink by clicking its type in the top list to reveal an options drop-down. Although Neutral Density is the default for Image Trap Placement, this option becomes available when you have a specialty ink defined for a spot plate, such as a spot varnish. You can choose from Neutral Density, Transparent, Opaque, or Opaque Ignore. Opaque is often used for heavy nontransparent inks such as metallic inks, to prevent the trapping of underlying colors while still allowing trapping along the ink’s edges. Opaque Ignore is used for heavy nontransparent inks to prevent trapping of underlying color and along the ink’s edges. 866 CorelDRAW X5 The Official Guide ● Trap Width This option controls the overlap of adjacent colored objects into each other. The slightly overlapping colors prevent the appearance of white gaps due to misregistration when printing. The default Trap Width is 0.25 point. A larger number will accommodate larger printing errors due to older machinery. ● Black Trap Width This option controls the distance that inks spread into solid black, or the distance between black ink edges and underlying inks. It is used when the amount of black ink reaches the percentage specified in the Black Limit field (in the Thresholds area). ● Trap Color Reduction Use this option to prevent certain butt-aligned colors (areas on different plates that meet one another) from creating a trap that is darker than both colors combined. Values smaller than 100 percent lighten the color of the trap. ● Step Limit This option controls the degree to which components of butt-aligned color must vary before a trap is created, usually set between 8 and 20 percent. Lower percentages increase sensitivity to color differences and create larger traps. ● Black Limit This value controls the minimum amount of black ink required before the value entered in the Black Trap Width field is applied. CHAPTER 27: Printing: Professional Output 867 27 FIGURE 27-4 If your output device is equipped with In-RIP trapping, these options are available. ● Black Density Limit This option controls the neutral density value at, or above, the value at which the In-RIP feature considers it solid black. To treat a dark spot- color as black, enter its Neutral Density value in this field. ● Sliding Trap Limit This value sets the percentage difference between the neutral density of butt-aligned colors at which the trap is moved from the darker side of the color edge toward the centerline. Use this option when colors have similar neutral densities, to prevent abrupt shifts in trap color along a fountain fill edge, for example. ● Trap Objects to Images Choosing this option lets you create traps between vectors and bitmaps. ● Image Trap Placement This option sets where the trap falls when trapping vector objects to bitmap objects to either Neutral Density, Spread, Choke, or Centerline in this option’s drop-down list. Neutral Density applies the same trapping rules used elsewhere in the printed document. Using this option to trap a vector to a bitmap can cause uneven edges because the trap moves from one side of the edge to the other. Spread produces a trap in areas where bitmaps meet vector objects. Choke causes vector objects to overlap the bitmap (the bitmap is choked). Centerline creates a trap that straddles the edge between vectors and bitmaps. Trap Objects To Images must be checked for Image Trap Placement to have any effect. ● Internal Image Trapping This option creates traps within the area of a bitmap, which is useful when very high contrast and posterized images are part of a design. ● Trap Black-And-White Images Choosing this option performs trapping between vectors and black-and-white (monochrome) bitmaps. Setting Prepress Options The term prepress is used to describe the preparing of film for various printing processes. Choosing the Prepress tab displays all options controlling how your printing material will be produced, and which information is included on the page, as shown in Figure 27-5. Here’s what the options in the Prepress tab offer: ● Paper/Film Settings These two options specify negative/positive printing and on which side of the film the light-sensitive emulsion layer appears. Choose Invert to cause your output to print as a negative; choose Mirror to cause the image to print backward. Ask the press operator or service bureau which way their image setter is set up for film. ● Print File Information A Job Name/Slug Line text box is printed on each separation, to better visually identify each printed sheet. The path and filename of your document is used by default, but you can enter your own information. Choose Print Page Numbers 868 CorelDRAW X5 The Official Guide to print page numbers as defined in your CorelDRAW document; choose Position Within Page to print this information inside the page boundaries—outside is the default. ● Crop/Fold Marks Crop marks help locate your document’s page corners; fold marks indicate folds for a specific layout. Choose Crop/Fold Marks to print these markings. While this is selected, you can also choose Exterior Only to cause the marks to print only outside the page boundaries on your printing material, which produces a more polished final presentation. Both options are selected by default. ● Registration Marks and Styles Registration marks help to align each separation plate; the film print is used to make the plate, and the plates need to be precisely aligned when your piece is printed, or you get a “Sunday Funny Pages” finished output. Choosing Print Registration Marks (selected by default) includes these marks on your output. Use the Style selector to specify a mark shape; the selector includes a preview of both positive and negative versions. ● Calibration Bars and Densitometer Scales These two options enable you to include color calibration bars and densitometer scales outside the page boundaries of your printed material. Calibration bars are useful for evaluating color density accuracy by printing a selection of grayscale shades that may be used for measuring the density—or blackness value—of film or paper output. CHAPTER 27: Printing: Professional Output 869 27 FIGURE 27-5 Use these options to control how your output is produced and to add prepress information and markings. ● Bitmap Downsampling Unless you’ve imported a bitmap image whose resolution as placed in a document exceeds the maximum output resolution of the printing device, it’s not necessary to check either the Color & Grayscale or the Monochrome check boxes. This feature is provided as a time-saver: for example, if an image is greater than 300 dpi and your output device is only capable of a maximum of 300 dpi, time is wasted as excess data is spooled to the printer … and then discarded. ● Marks to Objects Choosing this option places the currently selected prepress marks around the bounding box containing the objects on each page. These appear regardless of whether the Crop/Fold Marks option is selected to print. Choosing PostScript Options None of the preceding information on separations and advanced trapping features will be meaningful if your chosen output is not to a PostScript device. If you don’t currently see the PostScript tab, shown in Figure 27-6, you need to define a different print driver on the General tab. PostScript options offer control over a specific type of page description language, Level 2, Level 3, the type of device, compatibility, and features covered next. 870 CorelDRAW X5 The Official Guide FIGURE 27-6 These options become available if your selected printer is PostScript compatible. You set the following options on the PostScript tab: ● Compatibility In most cases, the printer and the PPD (PostScript Printer Description) file you choose are automatically set with the Compatibility option, which determines which PostScript features the output device is capable of handling. Older printers may be limited to PostScript Level 1 or 2 technology; most new models are compatible with Level 3. If you’re unsure which to choose, check out the manufacturer’s FAQ area on their website or the physical printer documentation. ● Conform to DSC Document Structuring Convention (DSC) is a special file format for PostScript documents. It includes a number of comments that provide information for postprocessors. Postprocessors can shuffle the order of pages, print two or more pages on a side, and perform other tasks often needlessly performed by humans. ● Bitmaps Selecting Level 2 or 3 PostScript-compatible printers offers you the Compression Type option of Use JPEG to reduce printing time if you have bitmap images in your document. When this option is selected, the JPEG Quality slider is available for setting the quality of the bitmaps being printed. Keep in mind that JPEG is a lossy compression standard; some of the original image information is discarded, quality is compromised, and at high compression settings, a photograph can take on visual noise. ● Maintain OPI Links This option preserves links to server-based bitmap images, provided you have imported temporary low-resolution versions using the Open Prepress Interface (OPI) option when you created your CorelDRAW document. Using OPI, you can store high-resolution bitmap images in a printer’s memory, and work temporarily with an imported low-resolution version. When your document is printed, the lower-resolution version is swapped with the higher-resolution version. By default, this option is selected. ● Resolve DCS Links Desktop Color Separation (DCS) technology is similar to OPI; you use placeholders in your document that have links to digitally separated images for use in process or multi-ink printing. When this option is enabled, the linked images automatically replace the placeholder images at print time. By default, this option is selected. If this option is not selected, a prompt will appear while the document is being printed, so you can relink the files manually through directory boxes. ● Fonts PostScript printing devices can print Type 1, True Type, and OpenType fonts. Type 1 fonts are often preferred because the font data is written in PostScript language. OpenType fonts, when a typographer creates them, can be coded to Bézier curves (in which case programs recognize them as PostScript encoded) or to Quadratic B-Splines—which are usually interpreted by an application as True Type CHAPTER 27: Printing: Professional Output 871 27 in structure. A good reason to lean toward Type 1 fonts when you output to PostScript is that there is no ambiguity to the structure of a Type 1 font. CorelDRAW’s options let you control which fonts are used during printing. It’s more reliable to download the fonts to the printing device; this speeds printing and produces better-looking text. To enable this feature, select Download Type 1 Fonts. If this option is disabled, fonts are printed as curves, which can take a lot of printing time when you have a lot of text on a page. When you select the Download Type 1 Fonts option, the Convert True Type To Type 1 option becomes available (and selected by default). ● PDF Marks If your document is being prepared for printing as a composite to an Adobe PDF distiller, these options become available. You can specify how your PDF file initially displays when viewed in Adobe Acrobat Reader or in a third-party reader by using options in the On Start, Display selector. Choose Page Only, Full Screen, or Thumbnail view. You can also choose whether to Include Hyperlinks and/ or Include Bookmarks in the resulting PDF file. If you’re preparing a PDF to send to a service bureau for high-resolution output, don’t use hyperlinks; they mess up the appearance of your printed piece, and let’s get real—how does your intended audience click on a piece of paper to visit a website? ● Auto Increase Flatness This option lets you simplify the printing of curves by decreasing the number of straight vector lines that describe the curve. This option can be used as a last resort if you run into problems printing highly complex shapes in your CorelDRAW document, usually a printer memory problem, as in not enough memory. ● Auto Increase Fountain Steps This option makes the print engine examine your document for opportunities to increase the number of fountain steps in an effort to avoid fountain fill banding. Banding is the visible effect of not having enough sequential steps in a fountain fill; you see bands of gradually changing color instead of a smooth transition from one object area to another. Increasing the number of steps that describe a fountain fill will cause fountain fills to appear smoother, but it will also increase printing complexity and output time. ● Optimize Fountain Fills This option works in reverse of the previous option by setting the print engine to decrease the number of fountain steps set for objects in your document to the number of steps your printer is capable of reproducing. CorelDRAW’s Printing Issues Tab The process of verifying that every last detail in your document will print as expected is often called preflight, and the good news is that the Issues tab is your flight attendant. CorelDRAW examines the contents of your document and the printing options you’ve selected and then compares them with the capabilities of your selected printer and your 872 CorelDRAW X5 The Official Guide selected output material. Printing snafus are found automatically and flagged by warning symbols, as shown in the earlier illustration in this chapter about issues icons. Figure 27-7 is the Issues tab, which is divided into two sections; with Print Preview turned on, it’s both documented and visually obvious what this proposed print has going against it. The top half of the Issues dialog lists the preflight issues detected with a brief explanation. The bottom half explains the causes, identifies the exact problems, and offers suggestions and recommendations for correcting them. The Issues feature will not prevent you from printing your document. If you want, you can deactivate the feature by selecting the found issue in the upper portion of the tab and choosing “Don’t check for this issue in the future” at the bottom of the tab. This disables the detection of the issue in the Preflight Settings dialog. Clicking the Settings button opens this dialog, which also lets you save and load current settings for future use. Previewing Your Printed Document CorelDRAW’s Print Preview feature provides a very good way of viewing your document and performing minor touchups, and it’s fully integrated with CorelDRAW’s print engine. To open the Print Preview feature, click the Print Preview button from within the Print dialog. Print Preview also is available in the File menu. CHAPTER 27: Printing: Professional Output 873 27 FIGURE 27-7 If CorelDRAW anticipates printing problems, they’ll be explained in this dialog. . high contrast and posterized images are part of a design. ● Trap Black-And-White Images Choosing this option performs trapping between vectors and black-and-white (monochrome) bitmaps. Setting Prepress. fine details, particularly necessary if you’re using a bitmap image in part of your design. CHAPTER 27: Printing: Professional Output 865 27 ● Auto-spreading This option causes CorelDRAW s print. Width to set the Auto-spreading width of the outline to a constant width regardless of this color difference. When Auto-spreading is selected, choosing the Text Above option makes CorelDRAW ignore