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Lesson 4. Customizing Adobe PDF Output Q... > Using default compression settings

Using default compression settings

In this section, you'll compare the image quality and file size of four different PDF files prepared by converting a sample PostScript file to Adobe PDF four times, using a different predefined set of job options each time.

Start Acrobat.

Choose File > Open, and select the four Adobe PDF files—Color1.pdf, Color2.pdf, Color3.pdf, and Color4.pdf—in the Lessons/Lesson04 folder. (You can shift-click to select contiguous files.) Click Open.

Color1.pdf was created using the Distiller eBook job options, Color2.pdf was created using the Distiller Press job options, Color3.pdf was created using the Distiller Print job options, and Color4.pdf was created using the Distiller Screen job options.

Choose Window > Tile > Vertically to display all the files in the document pane. If needed, use the scroll bars to display the same area in each of the files.

At the default magnification, all four images look very similar.





Click several times with the zoom-in tool () or use the magnification pop-up menu to display each image at 400% magnification. Scroll as needed so that you can see the same area in each of the files.





In comparison with the other images, Color4.pdf (the screen-optimized file) has a more jagged display quality. Since Color4.pdf is intended for low-resolution, on-screen use, and especially for Web use where download time is important, it does not require as detailed a display quality. Screen-optimized files display more quickly than files with higher resolution images.

Select the hand tool ().

With the Color4.pdf window active, choose File > Close, and close the Color4.pdf file without saving any changes.

Choose Window > Tile > Vertically to resize the remaining three images.

Select the zoom-in tool and click twice in each document pane to display Color1.pdf, Color2.pdf, and Color3.pdf at 800% magnification. Scroll as needed to display the same area in the three files.

Color1.pdf (the eBook-optimized file) has the coarsest display quality. The eBook job options are chosen to balance image quality with a reasonable file size. The display quality of Color3.pdf (the print-optimized file) is very close to that of Color2.pdf (the press-optimized file). Color2.pdf is intended for high-resolution printing—it contains the most detailed image quality and has the largest file size.

Color1.pdf 76KB

Color2.pdf 956KB

Color3.pdf 872KB

Choose Window > Close All to close all three files without saving them.

Now you'll compare the file sizes of the four Adobe PDF files. (File size may vary depending on your platform.)

In Windows, use Windows Explorer to open the Lesson04 folder, and note the sizes of the four files. In Mac OS, open the Lesson04 folder, shift-click the Color1.pdf, Color2.pdf, Color3.pdf, and Color4.pdf to select all four files, and then choose File > Get Info > General Information.

Color4.pdf has the lowest image quality and the smallest file size, while Color2.pdf has the highest image quality and the largest file size. Note that the significantly smaller Color1.pdf file does indeed balance image quality with small file size.


File sizes may vary slightly depending on whether you are using a Windows or Mac OS system.

Close all open windows.

PDF creation often involves a trade-off between image quality and file compression. More compression means smaller file sizes but also coarser image quality, while finer image quality is achieved at the expense of larger file sizes. For information on the default job options, see “Changing the Distiller job options” in Lesson 3.

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