About Arbortext Styler > Document Preview and Publishing > PDF Configuration File for the PTC ALD Engine > Compression Level
  
Compression Level
You can reduce the size of an output PDF file by setting its compression level. The level of compression that is possible depends on the content of the PDF:
• Using a moderate compression will give the best quality output.
• PDFs that only contain text are already compressed as far as possible with the default settings
• When PDFs contain raster graphics (TIFF, JPEG, PNG, etc.), the default setting is to use the Flate (zip) lossless compression scheme
Compression settings are configured with the Compression element in a .appcf file, and its child elements. In the file, add the following element hierarchy to the required Print element:
Print
PDFPrinter
Compression
Text Compression
The attribute compressText for the Compression element activates compression for text and line art. Use the value yes.
Image Compression
Child elements of the Compression element define the compression level for images.
Image Type
Child element of Compression
Attributes and Values
Monochrome images
MonochromeImages
type
• auto — use most appropriate compression for image type
• ccitt3
• ccitt4
• flate
• none — do not compress
This option is ignored for linked images when passthrough is enabled (see the Images element, a child of PDFPrinter).
Grayscale images
GrayscaleImages
type
• auto — use most appropriate compression for image type
• flate
• jpeg
• none — do not compress
quality
Amount of compression to apply when printing to JPEG
• high
• low
• max
• med
• min
Color images
ColorImages
type
• auto — use most appropriate compression for image type
• flate
• jpeg
• none — do not compress
quality
Amount of compression to apply when printing to JPEG
• high
• low
• max
• med
• min
Retain Original JPEG File Size
You can bypass any image compression settings by using the option to pass images directly to PDFLib without processing in PTC ALD before output. With this option selected, JPEG files in PDF output will retain the same size as in original source.
The Images element in a .appcf file includes an option to process images in this way. In the file, add the following element hierarchy to the required Print element:
Print
PDFPrinter
Images
Give the linked attribute for the Images element a value of passthrough.
EPS Files with Vector Graphics
You can set the level of PStill interpreter accuracy, which can reduce the size of EPS files containing vector graphics, especially those with many curves. 
The Images element in a .appcf file includes an option to set the DPI to use when converting EPS files. In the file, add the following element hierarchy to the required Print element:
Print
PDFPrinter
Images
Give the epsDPI attribute for the Images element a value that represents the required setting, for example 600.