Adobe 22002484 User Guide - Page 67

USING ACROBAT 9 STANDARD 62 Creating PDFs Optimization Options dialog box The Optimization Options dialog box for image settings controls how scanned images are filtered and compressed for the PDF. Default settings are suitable for a wide range of document pages, but you may want to customize settings for higher-quality images, smaller file sizes, or scanning issues. Automatic Applies default settings to balance file size and quality at a moderate level. • Aggressive Applies settings that minimize file size. In some cases, selecting this option may visibly affect the quality of the scanned PDF. Custom Settings Makes additional settings available under Compression and Filtering and disables the Aggressive setting under Automatic. If you select Custom Settings, the Color/Grayscale or Monochrome settings are available, depending on the option you selected in the Acrobat Scan dialog box. Color/Grayscale settings When scanning color or grayscale pages, select one of the following: • Lossless Does not apply compression or filters-such as Deskew, Background Removal, and so forth-to scanned pages. • 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 Last updated 9/30/2011