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54
Adobe Acrobat Help
Acrobat Distiller Options
Using Help
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Contents
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54
If you select the Automatic option, Acrobat determines the best compression method and
quality for your color or grayscale images. For most PDF files, this provides satisfactory
results. JPEG is applied to 8-bit grayscale images and to 8-bit, 16-bit, and 24-bit color
images when the images have continuous, smooth tones. ZIP is applied to 2-bit, 4-bit, and
8-bit grayscale images; to 4-bit color images and indexed 8-bit color images; and to 16-bit
and 24-bit color images when the images have sharp color changes.
5
To resample monochrome images, choose Average Downsampling To, Subsampling To,
or Bicubic Downsampling To, and enter a resolution in dpi in the Monochrome Images
area. Then enter a resolution in dpi in the For Images Above text box. Acrobat resamples
all monochrome images that are above this threshold in a PDF file.
Use the same resolution as the output device, but be aware that saving a monochrome
image at a resolution higher than 1500 dpi increases the file size without noticeably
improving image quality.
Note:
Resampling monochrome images can have unexpected viewing results, such as no
image display. If this happens, turn off resampling and convert the file again. This problem
is most likely to occur with subsampling and least likely with bicubic downsampling.
6
To apply compression to monochrome images, select Compression in the Monochrome
Images area, and choose CCITT Group 4, CCITT Group 3, ZIP, or Run Length compression.
Acrobat applies the compression to all monochrome images in a PDF file.
Note:
Make sure that monochrome images are scanned as monochrome and not as
grayscale. Scanned text is sometimes saved as grayscale images by default. Grayscale text
compressed with the JPEG compression method is muddy at best and may be unreadable.
7
To smooth jagged edges in monochrome images, select Anti-Alias to Gray.Then choose
2 bit, 4 bit, or 8 bit to specify 4, 16, or 256 levels of gray. (Anti-aliasing may cause small type
or thin lines to look blurry.)
8
Select Compress Text and Line Art to apply the ZIP compression method to all text and
line art in a PDF file. This method results in no loss of detail or quality.
Note:
If you selected Optimize for Fast Web View in the General settings, text and line art
are compressed regardless of what you choose here.
9
To apply the changes to the current job options, click OK. You cannot overwrite the
predefined sets of options. To save the changes as a different job options file and make
that the new job options file, click Save As.Then enter a name and location for the new set,
and click Save in the Save Job Options As dialog box. By default, these files are saved in the
Distillr/Settings folder (Windows) or Distiller/Settings folder (Mac OS) in the Acrobat
folder.
Applying different settings to different images
When Distiller processes a file, it normally applies your compression settings to images
throughout the file. If you want images in a file to be compressed and resampled using
different methods, you can do this in several ways:
•
Use the Adobe Photoshop application to resample and compress images before
processing with Distiller. In this case, you should deselect the compression and
downsampling or subsampling options in Distiller.
•
Create separate PostScript files for each part of the document you want to process
differently, and use different compression options to distill each part. Then use Acrobat