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USING ACROBAT 9 PRO
Creating PDFs
Last updated
9
/30/2011
Monochrome
When scanning black-and-white or monotone images, select one of the following:
•
JBIG2
Applies the JBIG2 compression method to black-and-white input pages. Settings of 0.95 or higher use the
lossless method; at lower settings, text is highly compressed. Text pages typically are 60% smaller than CCITT Group
4 compressed pages, but processing is slow. Compatible with Acrobat 5.0 (PDF 1.4) and later.
Note:
For compatibility with Acrobat 4.0, use a compression method other than JBIG2.
•
Adaptive
(As described under Color/Grayscale settings.)
•
CCITT Group 4
Applies CCITT Group 4 compression to black-and-white input page images. This fast, lossless
compression method is compatible with Acrobat 3.0 (PDF 1.2) and later.
Deskew
Rotates any page that is not square with the sides of the scanner bed, to make the PDF page align vertically.
Choose Automatic or Off.
Background Removal
Whitens nearly white areas of grayscale and color input (not black-and-white input).
For best results, calibrate your scanner’s contrast and brightness settings so that a scan of a normal black-and-white
page has dark gray or black text and a white background. Then, Off or Low should produce good results. If scanning
off-white paper or newsprint, use Medium or High to clean up the page.
Edge Shadow Removal
Removes dark streaks that occur at the edges of scanned pages, where the paper edge shadows
the scanner light. Choose Off, Cautious, or Aggressive.
Despeckle
Removes isolated black marks in black-and-white page content. Low uses a basic peephole filter. Medium
and High use both a peephole filter and a large area filter that removes larger spots farther from nearby features.
Descreen
Removes halftone dot structure, which can reduce JPEG compression, cause moire patterns, and make text
difficult to recognize. Suitable for 200–400-dpi grayscale or RGB input or, for Adaptive compression, 400–600-dpi
black-and-white input. The Automatic setting (recommended) applies the filter for 300 dpi or higher grayscale and
RGB input. Select Off when scanning a page with no pictures or filled areas, or when scanning at a resolution higher
than the effective range.
Halo Removal
When On (recommended), removes excess color at high-contrast edges, which may have been
introduced during either printing or scanning. This filter is used only on color input pages.
Scanning tips
•
Acrobat scanning accepts images between 10 dpi and 3000 dpi. If you select Searchable Image or ClearScan for PDF
Output Style, input resolution of 72 dpi or higher is required, and input resolution higher than 600 dpi is
downsampled to 600 dpi or lower.
•
To apply lossless compression to a scanned image, select one of these options under the Compression section in the
Optimization Options dialog box: CCITT Group 4 for monochrome images, or Lossless for color or grayscale
images. If this image is appended to a PDF document, and the file is saved by Save, the scanned image remains
uncompressed. If the PDF document is saved using Save As, the scanned image may be compressed.
•
For most pages, black-and-white scanning at 300 dpi produces text best suited for conversion. At 150 dpi, OCR
accuracy is slightly lower, and more font-recognition errors occur; at 400 dpi and higher resolution, processing
slows and compressed pages are bigger. If a page has many unrecognized words or very small text (9 points or
smaller), try scanning at higher resolution. Scan in black and white whenever possible.
•
When Recognize Text Using OCR is disabled, full 10-to-3000 dpi resolution range may be used, but the
recommended resolution is 72 and higher dpi. For Adaptive compression, 300 dpi is recommended for grayscale
or RGB input, or 600 dpi for black-and-white input.
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