Is it possible that a file size increases “by itself” during printing?
From the following Microsoft Support Article: "The size of the EMF spool file may become very large when you print a document that contains lots of raster data"
Symptoms When you print a document that contains lots of raster data, the size of the Enhanced Metafile (EMF) spool file may become very large. Files such as Adobe .pdf files or Microsoft Word .doc/.docx documents may contain lots of raster data. Adobe .pdf files and Word .doc/.docx documents that contain gradients are even more likely to contain lots of raster data.
Cause This problem occurs because Graphics Device Interface (GDI) does not compress raster data when the GDI processes EMF spool files and generates EMF spool files.
This problem is very prominent with printers that support higher resolutions. The size of the raster data increases by four times if the dots-per-inch (dpi) in the file increases by two times. For example, a .pdf file of 1 megabyte (MB) may generate an EMF spool file of 500 MB. Therefore, you may notice that the printing process decreases in performance.
Resolution
To resolve this problem, bypass EMF spooling. To do this, follow these steps:1. Open the properties dialog box for the printer. 2. Click the Advanced tab. 3. Click the Print directly to the printer option.Note This will disable all print processor-based features such as the following features:
- N-up
- Watermark
- Booklet printing
- Driver collation
- Scale-to-fit
TL;DR - Your PDF file didn't increase in size. It is only a large spool file that was created. It's nothing to worry about but Microsoft provides a solution listed above to prevent that situation from happening again (with a reduction of features).
There are a number of reasons why a print file may be a lot larger than the original PDF/DOC/PPT, etc.
The first one applies particularly to files that started out as PowerPoint (PPT) presentations. A presentation typically has the same background graphics on every slide. In the PPT file (or a PDF created from it) that graphic only appears once, and every slide has a reference to it. In the print file, that same graphics will be added once for every slide. A 1 MB graphics in a 20 page page presentation will thus become 20 MB in the spool file. And it could be a lot larger, because of the next issue.
An image may grow when sent to a printer, depending on the printer model. Suppose you have a 1000 x 1000 pixel colour image. The displayed size of it is such that, when printed, it will show as 10" x 10". If you use a PCL5 or GDI printer that is set for 300 dpi, that image will be sent as a 3000 x 3000 pixel image (10 x 300) to account for the printer's resolution. So it is suddenly 9 times larger. This would not happen with PostScript printers, as they are capable of scaling images to suit.
Some people think that, if an image will be printed on a 1200 dpi printer, it needs to be scanned at 1200 dpi for best results, giving a size increase of 16 times compared to 300 dpi. In fact, for printing you only need 300 dpi, regardless of printer resolution. For most applications even 200 dpi will be perfectly adequate. Only for top-end prints (on a printer capable of 2400 dpi or better) would you scan at 600 dpi.
Note that here are no desktop printers capable of printing better than 1200 dpi (1440 dpi for some inkjets). Any higher quoted "resolution" is only intended to give an idea of the quality of the printer's halftoning (the ability to print shades of colour).
It is a misconception. The size shown in the printer dialogue is not the file size, it is the size of the print data (the size of the spool for the print job).
Your file size has not changed.