Images from PowerPoint and Other Applications
Many modern applications whose principal purpose is not image editing can now save images at higher resolutions than they could in the past. Also, it is increasingly common that software programs that use vector graphics (for text, line drawings, and symbols) can export those graphics as bitmapped images. If an application can export images in TIFF or EPS format at the desired resolutions, it may be possible to use these images for publication. Publication images are typically desired at 300 or 400 ppi or dpi at width and height dimensions determined by the author according to the number of columns the image will span. Line drawings, graphs, and artwork are required at 1200 pixels or dpi.
Yet many of these programs save only in the JPEG format, and then only at relatively high levels of compression, resulting in a significant loss of visual data. The resolutions that result from saving as TIFF from these programs may also be less than what can be obtained through means discussed in this section. In Figure 4.24, for example, a zoomed image of a leaf shows that better resolution was achieved (on the left) when printing to Adobe PDF (Portable Document Format) using the Press Quality preset, versus saving a 300 ppi TIFF file from PowerPoint (right image). Note the coarser pixilation of the PowerPoint derived image.
Figure 4.24 A zoomed image of a leaf printed to Adobe PDF (left) and as a TIFF file saved in PowerPoint (right).
Also, many specialized graphing programs, older scientific programs, legacy QuickDraw programs, and programs on SGI (Silicon Graphics, Inc.)/SUN units do not provide any options for saving as TIFF or EPS through the Save As or Export commands. When documents from these sources are made into TIFF files, lettering and edges of drawings can be aliased.
Copy and Paste as a (Poor) Solution
Whenever possible, copying and pasting images from one application to another should be avoided. This is especially true when copying images and graphics from one software manufacturer (e.g., Microsoft) to another (e.g., Adobe). Copied graphics and images are saved at computer screen resolutions in memory (the Clipboard) at resolutions that are generally lower than the original.
For example, in Figure 4.25 a small portion of a graph is zoomed in to inspect the quality of lettering. A copied and pasted image of the graph is shown on the top; the same graph printed to Adobe PDF and saved as an EPS file is on the bottom. Note the change in colors of the bars in the copied and pasted image, along with the pixilation of the graphic indicated by the 5 and 0 in the number 50. Colors also shifted in the PDF derived EPS file: The graph was created in a Microsoft program in which color management is not used, resulting in interpretation of the colors by the Adobe PDF driver.
Figure 4.25 On the top is a copied and pasted image of the graph; on the bottom is the graph printed to Adobe PDF and saved as an EPS file.
Best Methods for Retention of Resolution
To retain as much visual data as possible without aliased lettering, the following approaches can be used for graphic (vector) line drawings, graphs, text, and so on:
Low-tech solution 1. Enlarge the graphic to eight times its size and save or export it in bitmap format (e.g., TIFF, JPEG, BMP, PICT). When the file is opened in Photoshop, in the Image Size dialog box, change the dimensions and resolution to the desired settings (see "Resample for Output [Image Size]" in Chapter 8).
Choose this method when graphics are easily enlarged and an option exists to save in a bitmap format.
Low-tech solution 2. Print the graphic to an inkjet printer or a deskjet printer (but only if it is a vector graphic), scan the page at 1200 dpi in the grayscale or color mode, save it as a TIFF file, and then optimize the image in Photoshop. If the image is a graphic (text, line drawings, graphs), make the grayish paper background white and the lines/text dark (see "Problem Images" in Chapter 6).
Use this option when no other options exist for saving as a bitmap or when other solutions don't work.
Print to Adobe PDF. Rather than saving a file in PDF format, which is likely to produce a low-resolution file, instead use the Print command and choose the Adobe PDF driver (Figure 4.26). This generates an image file in Adobe PDF format that retains the full resolution and detail of the original image or graphic. This method requires the purchase of one of the versions of Adobe Acrobat.
Figure 4.26 On the left, the Windows Print dialog box, showing the Adobe PDF driver selected. Clicking the Properties button opens the Adobe PDF Document Properties dialog box, seen at right.
In Properties (or Options), be sure to indicate the intent. In the Default Settings drop-down list, choose either of the following:
- For images, choose High Quality Print. An image no greater than 450 ppi (pixels per inch) will result (Figure 4.26).
- For graphics, choose Press Quality. A 2400 ppi document will result.
Open the document in Adobe Acrobat and check to see if the entire image or graphic fits into the page. If the document does not fit, any of the following actions can be taken:
- If the image or graphic is rotated to the wrong orientation but it fits within the page, in Acrobat choose Document > Rotate Pages to return the graphic or image to the correct orientation.
- If the image or graphic doesn't fit within the page because it is at the wrong orientation, change it before printing the PDF again. To do this, choose Landscape or Portrait (whichever is appropriate) in the Layout tab of the Print dialog box in Acrobat 7 for Windows, or in the Page Setup dialog box (File > Page Setup) in Acrobat 7 for Macintosh or Acrobat 8 for either platform.
- If the image or graphic doesn't fit within the page and it is at the correct orientation, rescale the image to the page size or increase the page size, whichever is appropriate. Click the Advanced button to access these options (Figure 4.27).
Figure 4.27 The Paper Size or Scaling options can be changed to fit the image or graphic within the page size.
Once you've created a satisfactory PDF file, convert it to the appropriate final format by opening it in Acrobat and choosing File > Save As. The encapsulated PostScript (EPS) format is preferred for publications because it retains details in graphics and produces compact files. Also, EPS files are scalable, meaning that they can be scaled to any dimensions and still retain their inherent resolution, provided that the graphics are in vector format and the original contains no bitmapped images. The TIFF format is preferred for bitmapped images, although JPEG files can be used in word processing documents.