Chapter 19

Understanding Advanced Graphic File Types

• Linking to Better JPEG Graphics
• Publishing TIFF Resources for Your Clients
• Creating a TIFF Document
• Delivering Technical Artwork in EPS Format on the Web
• Creating an EPS Document
• Making Documents Portable with Adobe's PDF
• Creating a Portable Document
• Next Steps
• Q&A
  

The paradigm that we've been using to create graphics for Web distribution has been predominantly based on viewing pages via a 72 dpi monitor. All the tasks and examples shown to you are based on screen resolution. But what happens when you try to print graphics at 72 dpi? (See Figure 19.1.) Most of the time, the prints will be much lower in quality than what you desire.

Figure 19.1 : A 72 dpi print at high resolution.

One might think that the solution is to provide bitmap graphics with higher dpi settings, say 300 or 600 dpi. Unfortunately, there are drawbacks to simply increasing dpi, although at times it will work. The biggest problem is exponential file size increase. Remember that with the Web, everything is an issue of file size.

This book talks about many of the concerns you'll be facing when you distribute work to be viewed or printed over the Internet. Fonts, jaggies, and file size top the list. So how can you overcome these specific limitations and still accomplish the task of getting your information out the way you want?

That's why this chapter is here. This chapter discusses the first method that includes providing higher quality Joint Picture Experts Group (JPEG) images to your audience. It also discusses Encapsulated PostScript (EPS) and Portable Document Format (PDF) and how they can help overcome jaggies and font issues.

Linking to Better JPEG Graphics

Due to the 8-bit restriction of the Graphical Interchange Format (GIF) image, you may want to distribute higher quality JPEG images at your site, particularly if you're in the graphics field. Even though JPEG images use lossy compression, they can be set up to retain most of the image data in your original file. Decreasing the amount of compression will help alleviate lost data and in turn will give you better copies of the original data.

But what if you don't want to lose any data? Well, JPEG will always lose some image data when you save. Many times it will be unnoticeable to the eye onscreen. However, if you were to print the image at a high enough resolution, you would be able to see the missing data. Thus, distributing in Tagged Image File Format (TIFF) may be your best alternative if you wish to maintain printability at the high end. TIFF was designed for print media and uses lossless compression, meaning that you don't lose any data.

Publishing TIFF Resources for Your Clients

The TIFF image format is designed to maintain high bit-depth data. Its original intention was to allow scanned image data to be easily transferred cross-platform for the purpose of high-end printing. The file format can maintain bit depths up to 32 bits, which very few of us use; most of us only use TIFF format for its 24-bit capability. It can also store black-and-white or bitmap mode at the low end. The image format follows either RGB or CMYK color models for transfer, which means that it will work well for both screen and print files. An advantage to this format is that it will also allow extra data to be stored internally in the file, including alpha channels, gamma correction data, and other proprietary information.

Lossless File Formats

Because the TIFF format allows extremely descriptive data, it is designed to utilize internal compression. Most color TIFF files use Lepel-ZivWelch (LZW) compression. This compression scheme internally marks redundant data and replaces it with tokens. These tokens represent specific series of colors or patterns within the file. When a TIFF file is saved, the creator application will generally prompt the user to ask if he or she wishes to compress the file with LZW. LZW compression is a lossless compression scheme, meaning it will not loose any data from compressed to uncompressed file. The TIFF format also allows other types of compression-Comité Consultif International Téléphonique et Télégraphique (CCITT), JPEG, and Packbits. The most common, however, is LZW.

Creating a TIFF Document

Creating a TIFF document is as simple as saving a particular file. Because the format is designed to accept up to 64-bit colors, no reduction of colors is necessary-unlike the GIF format. To create a TIFF document in Adobe Photoshop, follow these steps:

1. Once you have created the image to save as TIFF (see Figure 19.2), choose the Save As option from the File menu.
2. Set the Save File as Format Type to TIFF.
3. Give the file a filename.
4. Once you have clicked the OK button, you will be prompted to choose a platform and whether you want LZW compression in the file. Note that the Macintosh/PC option does not mean that you can't open it from the other platform. It simply means that the file is internally marked to whichever platform the file is written.
5. Click the LZW box if you want to use compression to reduce the file size.

Figure 19.2 : The TIFF Options dialog box.

Delivering Technical Artwork in EPS Format on the Web

Generally EPS artwork is not distributed over the Web because browsers, such as Netscape, are not capable of reading the file. Viewing EPS files requires a multipurpose Internet mail extension (MIME) definition and an external helper application like GhostScript. Nonetheless, most EPS files distributed over the Web are done so that the audience can print them.

EPS files give us an advantage of letting users print an image or file at their printer's resolution. This gives them much better results than a printed bitmap. The problems of jaggies on technical artwork and font problems are also overcome due to the vector description in the EPS file.

EPS files undoubtedly work great on the Macintosh. Standards are pretty much adhered to, but on the PC side, EPS files are probably the worst format to deal with. EPS on the PC comes in so many variations that some programs and printers will regurgitate on foreign EPS files. Use caution with EPS files in the Windows envi-ronment.

Creating an EPS Document

Once you've created artwork within a drawing program, it is easy to export an EPS version. Most packages such as Macromedia FreeHand, Adobe Illustrator, and CorelDRAW! store their native file format in EPS even though, for example, on a PC the extension says something other than EPS. To create an EPS file from Macromedia FreeHand, follow these steps:

1. Choose the Export option from the File menu and select EPS. (Note that in some packages EPS may be under the Save As option.)
2. If given an option, set the intended resolution to the intended resolution of the printer. You may also have the option to include font descriptions in the file as well.
3. Give the file a name and click OK.

Making Documents Portable with Adobe's PDF

Adobe's PDF is probably one of the most ingenious formats created in the past two years. One of the biggest problems in the printing industry, when it comes to digital files, is the font issue. You create a file, take it to someone else's computer (if they even have the same layout program you used), and print it. Everything is screwed up. Widows, orphans, and nasty-looking fonts appear. All the stinking technical glitches mess up your whole design. And in comes PDF (see Figure 19.3).

Figure 19.3 : The Acrobat Reader interface.

PDF was designed to allow a means of transporting design and page layout documents from one computer to another, regardless of the fonts used. In addition, the format is designed so you don't have to worry about whether the other computer has the same application for the document to print correctly. The PDF format stores not only all the text and graphics, it also stores the fonts and font characteristics and allows you to print from anywhere. And you can zoom in and out at your own leisure (see Fig-ure 19.4).

Figure 19.4 : Zooming in on a PDF file.

Sound too good to be true? To utilize the PDF format you must have Adobe's Distiller program. This is the program that actually creates the PDF file. The nice thing is that it's as easy as printing a document.

Once you have created a PDF document, you can open it into the Adobe Acrobat Reader. The reader is designed much like Microsoft's PowerPoint viewer. It allows you to play and view any PowerPoint slide file. The Acrobat Reader not only lets you view the document, but it also allows you to zoom in and out, rearrange graphics and text, and print. While maintaining the capability to print, the PDF format provides a slick way of transporting documents from one computer to another without worrying about fonts, graphics, or applications.

Creating a Portable Document

Once you have installed the Acrobat Distiller product, you will be able to create PDF documents. The Distiller adds a printer driver to your system. When you get ready to create the PDF file, print to this driver, which will write a PDF file to your hard drive. To create a PDF file, follow these steps:

1. Open your page layout program and the file you would like to make into a PDF file. Note that this will not affect the original document layout.
2. In the layout program, set the destination printer to the PDF driver. In some programs this is under page setup while in others it will be an option called Printer Setup in the File menu.
3. Choose the Print option from the File menu. The driver will now create a PDF file generated from the file you currently have open. That's all there is to it!

Next Steps

Now that you know how to use some of the other graphics formats available

• For more information on GIF and JPEG file formats, see Chapter 3 "Creating Cool Graphics for the Web."
• For information on including high resolution file links in your HTML page, see Chapter 7 "Designing Graphical Pages Anyone Can Download."
• For more information on interlaced or transparent GIFs, see Chapter 16, "Utilizing Inline Graphics to Your Advantage."
• For more information on converting graphics from one format to another, see Chapter 20, "Converting Graphics for Use on the Web."

Q&A