Adobe Acrobat 9 PRO Extended - Manual (Page 74)

68 USING ACROBAT 9 PRO EXTENDED
Creating PDFs
Last updated 9/30/2011
• Adaptive Divides each page into black-and-white, grayscale, and color regions and chooses a representation that
preserves appearance while highly compressing each type of content. The recommended scanning resolutions are 300
dots per inch (dpi) for grayscale and RGB input, or 600 dpi for black-and-white input.
• JPEG Applies JPEG compression to the entire grayscale or RGB input page.
Note: The scanner uses either the selected Color/Grayscale option or the selected Monochrome option. Which one is used
depends on the settings you select in the Acrobat Scan dialog box or in the scanner’s TWAIN interface, which may open
after you click Scan in the Acrobat Scan dialog box. (By default, the scanner application dialog box does not open.)
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.