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Adobe Acrobat Help
Acrobat Distiller Options
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Subsampling chooses a pixel in the center of the sample area and replaces the entire
area with that pixel at the specified resolution. Subsampling significantly reduces the
conversion time compared with downsampling but results in images that are less
smooth and continuous.
Setting the Distiller Compression job options
The Compression job options specify compression for text and line art, and compression
and resampling for images. Compression and resampling can significantly reduce the size
of a PDF file but can also degrade the quality of images. However, it does not affect the
quality of text and line art. You may want to experiment with these options to find an
appropriate balance between file size and image quality. (See
“Applying compression and
resampling” on page 51
.)
To set the Compression job options:
1
Select an existing set of job options from the Job Options menu to use as a starting
point.
2
Choose Settings > Job Options, and click the Compression tab.
3
To resample color or grayscale images, choose Average Downsampling To, Subsam-
pling To, or Bicubic Downsampling To, and enter a resolution in dots per inch (dpi) in the
Color Images or Grayscale Images area as appropriate.Then enter a resolution in dpi in the
For Images Above text box. Acrobat resamples all color or grayscale images with
resolution above this threshold.
The resolution setting for color and grayscale should be 1.5 to 2 times the line screen
ruling at which the file will be printed. (As long as you don’t go below this recommended
resolution setting, images that contain no straight lines or geometric or repeating
patterns won’t be affected by a lower resolution.)
You should also consider whether users will need to magnify a page. For example, if you
are creating a PDF of a map, consider using a higher image resolution so that users can
zoom in on the map.
The following table shows common types of printers and their resolution measured in
dots per inch (dpi), their default screen ruling measured in lines per inch (lpi), and a resam-
pling resolution for images measured in pixels per inch (ppi). For example, using the table,
if you were printing to a 600-dpi laser printer, you would enter 170 for the resolution at
which to resample images.
4
To apply compression to color or grayscale images, select Compression in the Color
Images or Grayscale Images area as appropriate, and choose Automatic, JPEG, or ZIP
compression, and a quality setting. Acrobat applies the compression to all color or
grayscale images in a PDF file.
Printer resolution
Default line screen
Image resolution
300 dpi (laser printer)
60 lpi
120 ppi
600 dpi (laser printer)
85 lpi
170 ppi
1200 dpi (imagesetter)
120 lpi
240 ppi
2400 dpi (imagesetter)
150 lpi
300 ppi