Adobe InDesign CC 2015 - Manual (Page 535)

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Exporting and publishing
Last updated 6/6/2015
The interpolation method you choose determines how pixels are deleted:
Average Downsampling To
Averages the pixels in a sample area and replaces the entire area with the average pixel color at the specified resolution.
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.