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- Compression - Determines the type of compression that is used:
- Automatic (JPEG)
- Determines automatically the best quality for color and grayscale images. For most files, this option produces satisfactory results.
- Is suitable for grayscale or color images. JPEG compression is lossy, which means that it removes image data and may reduce image quality; however, it attempts to reduce file size with a minimal loss of information. Because JPEG compression eliminates data, it can achieve much smaller files sizes than 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. ZIP compression can be lossless or lossy, depending on the Image Quality setting.
- JPEG 2000
- Is the international standard for the compression and packaging of image data. Like JPEG compression, JPEG 2000 compression is suitable for grayscale or color images. It also provides additional advantages, such as progressive display. The JPEG 2000 option is only available when Compatibility is set to Acrobat 6 (PDF 1.5) or later.
- Automatic (JPEG 2000)
- Determines automatically the best quality for color and grayscale images. The Automatic (JPEG 2000) option is only available when Compatibility is set to Acrobat 6 (PDF 1.5) or later.
- CCITT And Run Length
- Are only available for monochrome bitmap 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. Group 4 is a general-purpose method that produces good compression for most monochrome images. Group 3, used by most fax machines, compresses monochrome bitmaps one row at a time. Run Length compression produces the best results for images that contain large areas of solid black or white.
Note: Grayscale images that have been colorized in InDesign are subject to the compression settings for Color Images. However, grayscale images colorized with a spot color (and [None] applied to their frames) use the compression settings for grayscale.
Do you know what the differences between Automatic Jpeg and Jpeg is regarding file sizes and quality? Is Auto jpeg better quality but bigger file sizes than jpeg? What are the pros and cons of using one instead of the other seeing as they both say Jpeg?
Is this another innovation for electronic publication? IDCS4's PDF presets for Zip compression have Image Quality greyed out.
Edit: To answer my own question, the same explanation appears in the IDCS4 Help PDF.
Message was edited by: David W. Goodrich
On behalf of Adobe and to be very specific ...
There is a very major difference between Automatic(JPEG) and JPEG.
With the JPEG option, compression is always lossy JPEG compression using the chosen quality setting.
With the Automatic(JPEG) option, each image is analyzed and depending upon the image content, JPEG or ZIP compression would be used. If the image is “photographic” in nature, lossy JPEG compression is used with the quality setting chosen. If the image is effectively a raster representation of mostly text and/or vector content (such as many screen shots, especially of menus or dialog boxes), lossless ZIP compression, using indexed color if less than 256 distinct colors, is chosen to avoid imaging artifacts that JPEG compression can introduce for such content.
Automatic(JPEG2000) works similarly, except that lossy JPEG2000 compression is used for the photographic images. (JPEG2000 compression in PDF requires at least PDF 1.5 compliance).
In general we recommend Automatic(JPEG) with quality set to Maximum as the best compromise for image quality and file size, including for most critical high resolution printing. My personal high quality printing experience confirms this recommendation. (Note that there are purists who never allow any “lossy” compression such as JPEG for any content, but I have yet to see any real world benefit of that unless you examine you images with very high power magnifiers!)
Thanks Dov, that answered my question perfectly.
Sorry I got sidetracked by shiny things yesterday (aka work). My answer would not have been as comprehensive as the one supplied by Dov.
I'll have to save that as a note
No worries, all input thanfully received...