Adobe 22020737 Acrobat X Pro Manual - Page 329

USING ACROBAT X PRO 323 Editing PDFs Specify the following options, as needed: Downsample Reduces file size by lowering the resolution of images, which involves merging the colors of original pixels into larger pixels. Note: Masked images and images with a size less than 16-by-16 pixels are not downsampled. Compression Reduces file size by eliminating unnecessary pixel data. In general, JPEG and JPEG 2000 compression give better results on images like photographs with gradual transitions from color to color. ZIP is the better choice for illustrations with large areas of solid, flat color, or patterns made up of flat colors. For monochrome images, JBIG2 compression, which is available in PDF Optimizer but not in Distiller, is superior to CCITT. Quality Available only for JPEG and JPEG 2000 formats. JPEG and JPEG 2000 compression methods are typically lossy, a process that permanently removes some pixel data. You can apply lossy JPEG or JPEG 2000 compression to color images at various levels (minimum, low, medium, high, maximum). For JPEG 2000 compression, you can also specify lossless so that no pixel data is removed. Compression for monochrome images is lossless, except for JBIG2 compression, which provides both lossy and lossless modes of compression. Tile Size Available only for JPEG 2000 format. Divides the image being compressed into tiles of the given size. (If the image height or width is not an even multiple of the tile size, partial tiles are used on the edges.) Image data for each tile is individually compressed and can be individually decompressed. The default value of 256 is recommended. Optimize Images Only If There Is A Reduction In Size When selected, if the image setting will cause an increase in file size, the optimization for that image is skipped. Fonts panel To ensure an exact match to the source document, it's a good idea to embed all fonts used in the document. If you don't need an exact match and you prefer a smaller file, you can choose not to embed fonts for roman text and East Asian text (Traditional Chinese, Simplified Chinese, Korean, and Japanese). Text in these languages is replaced with a substitution font when viewed on a system that does not have the original fonts. The Fonts panel of the PDF Optimizer contains two lists for fonts: fonts that are available for unembedding, and fonts to unembed. Certain fonts aren't available for unembedding and don't appear in the Fonts panel. To unembed fonts in a document, select one or more fonts in the Embedded Fonts list, and click the Unembed button. If you don't want to embed subsets of the embedded fonts, deselect Subset All Embedded Fonts. To prevent unembedding for all fonts in the document, select Do Not Unembed Any Font. Transparency panel If your PDF includes artwork that contains transparency, you can use presets in the Transparency panel of PDF Optimizer to flatten transparency and reduce file size. (Flattening incorporates transparency into corresponding artwork by sectioning it into vector-based areas and rasterized areas.) PDF Optimizer applies transparency options to all pages in the document before applying other optimization options. If you select the Acrobat 4.0 And Later compatibility setting, the Transparency panel is enabled and all transparency in the file is flattened during optimization. This ensures compatibility with Acrobat 4.0 and earlier, which doesn't support transparency. When you create flattening presets, they appear with the default presets in the Transparency panel. Note: Transparency flattening cannot be undone after the file is saved. Discard Objects panel The Discard Objects panel lets you specify objects to remove from the PDF and lets you optimize curved lines in CAD drawings. You can discard objects created in Acrobat and in other applications. Selecting an object removes all occurrences of that object within the PDF. Last updated 10/11/2011