Image Compression
To get smaller file size, you can set image compression in the following ways:
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choose a predefined compression control from the PDF Create Profiles dialog box for a selected profile.
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for documents with text and pictures, scanned to image files, use MRC compression.
PDF Create offers options to let you choose the best compromise between image quality and file size. The higher the compression, the smaller the file and the less quality it will have. If you want to keep the original image quality, you must choose lossless.
Compression controls
PDF Professional provides the following predefined compression controls:
Lossless (level 100)
High Quality (level 75)
Medium Quality (level 50)
Low Quality (level 25)
Image Place Holder (level 5)
No Image (level 0)
You can use these compression controls with Auto Settings and also in Custom Settings. See more about this in the Compression Controls topic.
MRC compression
The above mentioned image compression algorithms are useful in general cases and can also be effective for PDF files with a combination of textual and image data. The MRC (Mixed Raster Content) compression technology is of value in the following cases:
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When the input is taken from image files resulting from scanning.
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When these files contain both text and color or grayscale pictures or backgrounds.
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When reducing the PDF file size is desired.
Traditional compression methods apply one value to the whole file content, which may be too high for some elements, too low for others and optimal for neither. MRC separates the text elements from the pictures or backgrounds and applies optimum compression to each. This can yield PDF files up to ten times smaller than traditional methods, with less compromising of file quality. MRC offers no benefit for black-and-white files, for text-only or picture-only files – the program examines input files and will not apply MRC in these cases, even if you specified it.
Nuance PDF Create Assistant provides a predefined profile for MRC compression and you can also use this compression method with other profiles.
To use the ‘PDF with MRC Compression’ profile in PDF Create Assistant
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Open the Nuance PDF Create Assistant.
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In the
Profile selection box, select PDF with MRC Compression.
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Click the Profiles… button to check settings in the PDF Create Profiles dialog box. Compression is automatically set to Lossless (level 100) and the MRC checkbox is turned on. Keep these settings and change other settings (e.g. security, watermark, etc.) if required.
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Click the Settings… button to display the MRC PDF Conversion Settings dialog box. Select which image quality is needed for MRC compression, then close the dialog box.
To use MRC compression with any profiles
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Open the Nuance PDF Create Assistant.
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In the
Profile selection box, select a profile.
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Click the Profiles… button.
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In the PDF Create Profiles dialog box, set Compression to Lossless (level 100) and turn on the MRC checkbox.
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Click the Settings… button to display the MRC PDF Conversion Settings dialog box. Select which image quality is needed for MRC compression, then click OK.
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In the PDF Create Profiles dialog box check and change other settings (e.g. security, watermark, etc.) if required. Click OK.
Note
MRC compression should not be combined with other program compression – both act and would lower quality too much. Using the MRC profile as delivered avoids this, since it sets program compression to lossless (100%), leaving MRC to do all the work. When processing without a profile, you should set little or no program compression when MRC is enabled and expected to run.
Tip
To get a Searchable PDF from image-only input, along with MRC compression, turn on both checkboxes.
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