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<< Click to Display Table of Contents >> Embedded Images |
  
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<< Click to Display Table of Contents >> Embedded Images |
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VPE automatically embeds all images into PDF files.
The following rules apply:
Metafiles (WMF) and Enhanced Metafiles (EMF) are converted into true-color (24-bit) bitmaps, since the PDF file format does not support metafiles. Note: metafiles contain also resolution information, similar to the DPI resolution information in bitmaps. VPE analyses their resolution information and creates bitmaps of the same resolution. Many metafiles are written in a very high resolution, which causes VPE to create huge bitmaps, which causes high temporary memory consumption. We recommend to care for the resolution information of metafiles and to keep it low, say between 96 and 300 DPI, or to use the DocExportPictureResolution property in order to force all images embedded into PDF documents to be scaled down automatically to a fixed resolution.
JPEG images are embedded with their original JPEG compression and in their original RGB or CMYK format, i.e. VPE analyses JPEG files and copies their relevant data directly and unmodified - without uncompression and/or re-compression - into the PDF file.
Black and White bitmap images - regardless of their file type, e.g. BMP, PNG, TIFF CCITT FAX G3 or G4, etc. - are written as black and white (1-bit) images into the PDF files. They are always re-compressed using flate compression (i.e. ZLIB compression).
Palette images with 256 – or less – colors are written as palette images, using flate compression.
All other bitmap images are converted to true-color (24-bit) bitmaps and are then flate compressed.