PDF File Size Comparisons

In this article, I'll show the results of some PDF file size comparisons I performed printing from MicroStation 8.5, 8.9, and 8.11. I'll also compare PDF file sizes produced by MicroStation 8.11 printing to both pdf.pltcfg and the Adobe Acrobat 8 Standard Windows printer driver. You should be able to reproduce these results if you care to.

In all cases, I printed using the default Untitled workspace and the standard, unmodified pdf.plt / pdf.pltcfg printer driver configurations delivered with the product. I opened the same design files in all versions of MicroStation.

For my non-rasterized-print test case, I wanted a representative medium-density vector drawing with no raster or OLE content. I chose the BSI400-P01-Plan_Profile.dgn delivered in the MicroStation Examples/Civil workspace. I printed this sheet model maximized to ANSI D paper size.

For my rasterized-print test case, I chose the BSI300G1001-Cover.dgn delivered in the MicroStation Examples/Building workspace. This design contains vector data, a raster attachment, and a smooth-shaded reference attachment. I printed this sheet model maximized to ISO A2 paper size. For this data case, I combined all the design and data files into a single folder so that the file would open correctly in the Untitled workspace. When printing from MicroStation 8.5, I also had to modify pdf.plt to swap in the ISO paper sizes.

Here are the output PDF file sizes I obtained printing BSI400-P01-Plan_Profile.dgn to the MicroStation PDF printer driver in non-rasterized mode:

1144 KB - MicroStation

1137 KB - MicroStation

522 KB - MicroStation

Here are the output PDF file sizes I obtained printing BSI300GI001-Cover.dgn to the MicroStation PDF printer driver in rasterized mode:

5227 KB - MicroStation

9244 KB - MicroStation

3822 KB - MicroStation

MicroStation 8.11 shows a clear improvement in PDF output file size when compared to both MicroStation 8.5 and 8.9. This is due to a number of factors, including an increase in the level-of-detail threshold in the default pdf.pltcfg, improvements to the implementation of raster quality factor when printing in rasterized mode, and a more compact numerical representation in the PDF file.

I also wanted to see how the PDF printer driver in MicroStation 8.11 compared with the Windows printer driver delivered with Adobe Acrobat Standard 8. This was a bit of a challenge, as the Adobe PDF printer has countless settings that make an apples-to-apples comparison difficult. Here are the modifications I made to the Adobe printer driver's default Standard settings:

• Changed the printer resolution from 1200 DPI to 600 DPI to match pdf.pltcfg.

• Added paper sizes for ANSI D and ISO A2.

• For each of the three image types, turned off image downsampling, changed the compression mode to ZIP, and changed the image resolution to 600 DPI to match pdf.pltcfg. (Note that since I was only printing raster content in rasterized mode, the 600 DPI pdf.pltcfg rasterized resolution was the important value, not the 300 DPI raster resolution that would have been used in a non-rasterized print.)

With these settings, here are the output PDF file sizes I obtained printing the same data cases from MicroStation using the standard printer.pltcfg in conjunction with the Adobe PDF Windows printer:

590 KB - BSI400-P01-Plan_Profile.dgn (compare with 522 KB for pdf.pltcfg)

3613 KB - BSI300GI001-Cover.dgn (compare with 3822 KB for pdf.pltcfg)

These results show that the MicroStation 8.11 PDF printer driver produces comparable output file sizes with the Adobe PDF Windows printer when the print settings are roughly equivalent.

I could have achieved much smaller PDF files from both the MicroStation PDF printer driver and the Adobe PDF Windows printer driver by switching the raster compression mode from ZIP to JPEG. However, since I was printing in rasterized mode, the entire PDF would have been affected, producing undesirable compression artifacts around text and line work.

Of course, comparisons between pdf.pltcfg and printer.pltcfg become irrelevant when printing OLE objects in non-rasterized mode. In that case, the Windows printer driver wins out over the MicroStation PDF printer driver easily. This is because OLE ojects must be rasterized when printing to any non-Windows printer, whereas OLE objects such as Excel spreadsheets are printed as vector data when using printer.pltcfg.  For more information on this topic, refer to my blog article Printing Rasterized OLE Objects: Performance and PDF File Size.