Compression PDF Options


One of the benefits of creating PDF files is that they can be compressed to take up less space. You use the same types of controls for compressing both color and grayscale bitmap images .

The compression controls in the Export PDF dialog box for color and grayscale bitmap images.

To set the color or grayscale downsampling:

1.

Choose one of the following from the Sampling menu :

  • Do Not Downsample does not throw away any pixel information. Use this to maintain all information in the image.

  • Average Downsampling to averages the pixels in a sample area.

  • Subsampling to reduces processing time compared to downsampling, but creates images that are less smooth.

  • Bicubic downsampling to is the slowest but most precise method, resulting in the smoothest tonal gradations.

The Sampling menu for color and grayscale bitmap images.

2.

When you have set a downsampling method, enter an amount in the resolution field .

The Resolution fields for color and grayscale bitmap images.

Tip

For print work this setting is usually 1.5 times the line screen of the printing press.

Tip

For onscreen viewing this setting is usually 72 pixels per inch.

3.

Enter an amount in the field for images above a certain resolution .

Tip

This helps you downsample only high-resolution images without losing information in lower-resolution images.

To set the color and grayscale compression:

1.

Choose one of the following from the Compression menu :

  • None applies no compression to the image.

  • Automatic (JPEG) lets InDesign automatically determine the best quality for color and grayscale images.

  • JPEG applies a compression that is best for images with tonal changes.

  • ZIP applies a compression that is best for images with large areas of flat color.

  • JPEG 2000 is the international standard for the compression and packaging of image data. This option is only available for Acrobat 6 (PDF 1.5) or higher.

  • Automatic (JPEG 2000) automatically determines the best quality for color and grayscale images. This option is only available for Acrobat 6 (PDF 1.5) or higher.

The Compression menu for color and grayscale bitmap images.

2.

Choose a setting from the Image Quality menu :

  • Maximum sets the least amount of compression.

  • Minimum sets the most.

The Image Quality menu for color and grayscale bitmap images.

Tip

Use Maximum for high-end output.


There are different resolution and compression options for monochrome bitmap images (such as 1-bit scanned art) .

The compression controls for monochrome images.

To set the monochrome bitmap downsampling:

  • Choose one of the following from the Sampling menu :

    • Do Not Downsample does not throw away any pixel information. Use this setting if you want to maintain all the information in the image.

    • Average Downsampling to averages the pixels in a sample area.

    • Subsampling to is faster than downsampling, but creates images that are less smooth.

    • Bicubic downsampling to is the slowest but most precise method, resulting in the smoothest tonal gradations.

    The Sampling menu for monochrome images.

To set the monochrome bitmap resolution:

1.

When you have set a downsampling method, enter an amount in the resolution field .

The resolution fields for monochrome images.

Tip

For print work, this setting is usually the resolution of the output device with a limit of 1500 dots per inch.

2.

Enter an amount in the field for images above a certain resolution .

Tip

This helps you downsample only high-resolution images without losing information in lower-resolution images.

To set the compression for monochrome images:

1.

Choose one of the following from the Compression menu :

  • None applies no compression to the image.

  • CCITT Group 3 is similar to the compression used for faxes.

  • CCITT Group 4 is a general-purpose method that produces good results for most monochromatic images.

  • ZIP works well for black-and-white images that contain repeating patterns.

  • Run Length produces the best results for images that contain large areas of solid black or white.

The Compression menu for monochrome images.

2.

Check Compress Text and Line Art to further reduce the size of the file.

3.

Check Crop Image Data to Frames to delete the image outside the frame.

More Info on Color Profiles

If you are interested in learning more about color profiles, you should visit www.color.org. This is the home of the International Color Consortium. From their Web site:

The International Color Consortium was established in 1993 by eight industry vendors for the purpose of creating, promoting and encouraging the standardization and evolution of an open, vendor-neutral, cross-platform color management system architecture and components. The outcome of this cooperation was the development of the ICC profile specification.

The intent of the International Color Consortium (R) profile format is to provide a cross-platform device profile format. Device profiles can be used to translate color data created on one device into another device's native color space.




InDesign CS2 for Macintosh and Windows(c) Visual QuickStart Guide
InDesign CS4 for Macintosh and Windows: Visual QuickStart Guide
ISBN: 0321573579
EAN: 2147483647
Year: 2006
Pages: 309
Authors: Sandee Cohen

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