Adobe InDesign CS5 - Manual (Page 516)

510 USING INDESIGN
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Last updated 11/16/2011
• Subsampling To Chooses a pixel in the center of the sample area and replaces the entire area with that pixel color.
Subsampling significantly reduces the conversion time compared with downsampling but results in images that are
less smooth and continuous.
• Bicubic Downsampling To Uses a weighted average to determine pixel color, which usually yields better results
than the simple averaging method of downsampling. Bicubic is the slowest but most precise method, resulting in the
smoothest tonal gradations.
Compression Determines the type of compression that is used:
• Automatic (JPEG) Determines automatically the best quality for color and grayscale images. For most files, this
option produces satisfactory results.
• JPEG Is suitable for grayscale or color images. JPEG compression is lossy, which means that it removes image data
and may reduce image quality; however, it attempts to reduce file size with a minimal loss of information. Because
JPEG compression eliminates data, it can achieve much smaller files sizes than ZIP compression.
• ZIP Works well on images with large areas of single colors or repeating patterns, and for black-and-white images
that contain repeating patterns. ZIP compression can be lossless or lossy, depending on the Image Quality setting.
• JPEG 2000 Is the international standard for the compression and packaging of image data. Like JPEG compression,
JPEG 2000 compression is suitable for grayscale or color images. It also provides additional advantages, such as
progressive display. The JPEG 2000 option is only available when Compatibility is set to Acrobat 6 (PDF 1.5) or later.
• Automatic (JPEG 2000) Determines automatically the best quality for color and grayscale images. The Automatic
(JPEG 2000) option is only available when Compatibility is set to Acrobat 6 (PDF 1.5) or later.
• CCITT And Run Length Are only available for monochrome bitmap images. CCITT (Consultative Committee on
International Telegraphy and Telephony) compression is appropriate for black-and-white images and any images
scanned with an image depth of 1 bit. Group 4 is a general-purpose method that produces good compression for most
monochrome images. Group 3, used by most fax machines, compresses monochrome bitmaps one row at a time.
Run
Length compression produces the best results for images that contain large areas of solid black or white.
Note: Grayscale images that have been colorized in InDesign are subject to the compression settings for Color Images.
However, grayscale images colorized with a spot color (and [None] applied to their frames) use the compression settings
for grayscale.
Image Quality Determines the amount of compression that is applied. For JPEG or JPEG 2000 compression, you can
choose Minimum, Low, Medium, High, or Maximum quality. For ZIP compression, only 8-bit is available. Because
InDesign uses the lossless ZIP method, data is not removed to reduce file size, so image quality is not affected.
Tile Size Determines the size of the tiles for progressive display. This option is only available when Compatibility is set
to Acrobat 6 (1.5) and later, and Compression is set to JPEG 2000.
Compress Text And Line Art Applies Flate compression (which is similar to ZIP compression for images) to all text
and line art in the document, without loss of detail or quality.
Crop Image Data To Frames May reduce file size by exporting only image data that falls within the visible portion of
the frame. Do not select this option if postprocessors might require the additional information (for repositioning or
bleeding an image, for example).
Marks and Bleeds options for PDFs
Bleed is the amount of artwork that falls outside of the printing bounding box, or outside the crop marks and trim
marks. You can include bleed in your artwork as a margin of error, to ensure that the ink extends all the way to the
edge of the page after the page is trimmed or to ensure that a graphic can be stripped into a keyline in a document.
You can specify the extent of the bleed and add a variety of printer’s marks to the file.