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Color Bitmap Images:
To compress color images, select Downsample To and specify a dpi
value; InDesign only downsamples the image when its resolution exceeds 1.5 times the value
you specify. For compression, we recommend choosing Automatic, and setting Quality
to Maximum. Note that JPEG 2000 compression (available when you specify Acrobat 6
compatibility) may not be supported by all RIPs and prepress applications.
Grayscale Bitmap Images:
To compress grayscale images, select Downsample To and specify
a dpi value; InDesign only downsamples the image when its resolution exceeds 1.5 times the
value you specify. For compression, we recommend choosing Automatic, and setting Quality
to Maximum. Note that JPEG 2000 compression (available when you specify Acrobat 6
compatibility) may not be supported by all RIPs and prepress applications.
Monochrome Bitmap Images:
To compress one-bit images, select Downsample To and enter
the resolution of the final output device. Then, select CCITT Group 4 for the greatest lossless
compression. InDesign supports CCITT Group 3 and Group 4 compression options. CCITT
Group 3, which is used by most fax machines, compresses monochrome bitmaps one row at
a time. Another option, Run Length, is a lossless compression option that produces the best
results for images with large areas of solid white or black.
Compress Text and Line Art:
This is selected by default; we recommend leaving it selected.
InDesign uses lossless compression, so the quality of these elements in your PDF file won’t be
affected.
Crop Image Data to Frames:
This option may reduce file size by exporting only image data
that falls within the visible portion of the frame. Don’t select this option if post-processors
might use the additional information (for repositioning or bleeding an image, for example).
