This option results in no loss of detail or quality.įonts option: The Subset Embedded Fonts When Percent Of Characters Used Is Less Than option specifies when to embed the entire font (as opposed to just the characters used in the document) based on how many of the font's characters are used in the document. This option determines the size of the tiles for progressive display.Ĭompress Text And Line Art option: The Compress Text And Line Art option applies ZIP compression to all text and line art in the file. Tile Size option: The Title Size option is only enabled when the compression setting is JPEG2000. Using 4-bit ZIP compression with 8-bit data can affect the quality, however, because data is lost. That is, data is not removed to reduce file size, so image quality is not affected. If you use 4-bit ZIP compression with 4-bit images, or 8-bit ZIP compression with 4-bit or 8-bit images, the ZIP method is lossless. For ZIP compression, Illustrator provides 4-bit and 8-bit Quality options. For JPEG compression, Illustrator provides Minimum, Low, Medium, High, and Maximum Quality options. The available options depend on the compression method. Run Length compression produces the best results for images that contain large areas of solid black or white.Ĭompression (Image Quality): Determines the amount of compression that is applied. Group 3, used by most fax machines, compresses monochrome bitmaps one row at a time. ![]() ![]() Group 4 is a general-purpose method that produces good compression for most monochrome images. CCITT (Consultative Committee on International Telegraphy and Telephony) compression is appropriate for black-and-white images and any images scanned with an image depth of 1 bit. It also provides additional advantages, such as progressive display.ĬCITT and Run Length compression are only available for monochrome bitmap images. Like JPEG compression, JPEG2000 compression is suitable for grayscale or color images. JPEG2000 is the new international standard for the compression and packaging of image data. Because JPEG compression eliminates data, it can achieve much smaller file sizes than ZIP compression. However, it attempts to reduce file size with a minimal loss of information. JPEG compression is lossy, which means that it removes image data and can reduce image quality. JPEG compression is suitable for grayscale or color images. ZIP compression can be lossless or lossy, depending on the Quality setting. ZIP compression works well on images with large areas of single colors or repeating patterns, and for black-and-white images that contain repeating patterns. Use Automatic (JPEG2000) for superior compression. Use Automatic (JPEG) if you need the greatest compatibility. For most files, this option produces satisfactory results. The Automatic option automatically sets the best possible compression and quality for the artwork contained in the file. Subsampling significantly reduces the conversion time compared with downsampling, but results in images that are less smooth and continuous.Ĭompression (Compression): Determines the type of compression used. Subsampling chooses a pixel in the center of the sample area and replaces the entire area with that pixel color.Bicubic is the slowest but most precise method, resulting in the smoothest gradations. Bicubic Downsampling uses a weighted average to determine pixel color, which usually yields better results than the simple averaging method of downsampling.Average Downsampling averages the pixels in a sample area and replaces the entire area with the average pixel color at the specified resolution. ![]() The interpolation method you choose determines how pixels are deleted: ![]() Illustrator downsamples all images with resolution above this threshold. Then, enter a resolution in the For Images Above box. To downsample color, grayscale, or monochrome images, choose an interpolation method, enter the desired resolution (in pixels per inch). Deselect the option to disable all downsampling options.ĭownsampling refers to decreasing the number of pixels in an image. If you plan to print the PDF file at high resolution, then don't use downsampling. Each section provides the following options for compressing and resampling color, grayscale, or monochrome images.Ĭompression (Downsampling): If you plan to use the PDF file on the web, then use downsampling to allow for higher compression. The Compression area of the Adobe PDF Options dialog box contains three sections. Depending on the settings you choose, compression and downsampling can significantly reduce the size of a PDF file with little or no loss of detail and precision. When you save an Illustrator file as a PDF file, you can compress text and line art, and downsample bitmap images.
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