Prevent Ghostscript from rasterizing text?

Question

I'm trying to convert PDFs to PCL (using ghostscript, but I'd love to hear alternative suggestions), and every driver (ghostscript device), including all of the built-ins and gutenprint generate PCL files many times larger than the input PDF. (This is the problem - I need my PCL to be about as small as the input).

Given that the text doesn't show up in the PCL file, I guess that Ghostscript is rasterizing the text. Is there a way to prevent GS generally, or just gutenprint, from doing that? I'd rather either have it embed the fonts, or not even embed the fonts (leave it to the printer to render the fonts)?

Unfortunately, there doesn't seem to be any documentation on this point.

Answer 1

There are 3 (I think) types of font in PCL. There are rendered bitmaps, TrueType fonts (in later versions) and the HPGL stick font.

PDF and PostScript Have type 1, 2 (CFF), 3 and 42 (TrueType, but not the same as PCL) and CIDFonts based on any of the preceding types.

The only font type the two have in common is TrueType, so in order to retain text, any font which was not TrueType would have top be converted into TrueType. This is not a simple task. So Ghostscript simply renders the text, which is guaranteed to work.

PDF is, in general, a much richer format than PCL< there are many PDF constructs (fonts, shading, stroke/fill in a single operation, transparency) which cannot be represented in PCL. So its entirely possible that the increase in size is nothing to do with text and fonts.

In fact, I believe that the PXL drivers in Ghostscript simply render the entire page to a bitmap at the required resolution, and then wrap that up with enough PCL to be successfully sent to a printer. (I could be mistaken on this point though)

Basically, you are not going to get PCL of a similar size to your PDF out of Ghostscript.

Answer 2

Here is a way to 'prevent Ghostscript from rasterizing text'. But its output will be PostScript. You may however succeed convert this PostScript to a PCL5e in an additional step.

The method will convert all glyphs into outline shapes for its PostScript output, and it does not work for its PDF or PCL output. The key here is the -dNOCACHE parameter:

gs -o somepdf.ps -dNOCACHE -sDEVICE=pswrite somepdf.pdf

Of course, converting font glyphs to outlines will take more space than keeping the original fonts embedded, because "fonts" are a space-optimized concept to store, retrieve and render glyph shapes.

Once you have this PostScript, you may be able to convert it to PCL5e with the help of either of the methods you tried before for PDF input (including {Apache?} FOP).

However, I have no idea if the output will be much smaller than versions with rasterized fonts (or even wholesome rasterized pages). But it may be worth a test.

Now vote down this answer too...

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Update

Apparently, from version 9.15 (to be released during September/October 2014), Ghostscript will support a new command line parameter:

 -dNoOutputFonts

which will cause the output devices pdfwrite, ps2write and eps2write to "to 'flatten' glyphs into 'basic' marking operations (rather than writing fonts to the output)".

That means that the above command should be replaced by this:

 gs -o somepdf.ps -dNoOutputFonts -sDEVICE=ps2write somepdf.pdf

Caveats: I've tested this with a few input files using a self-compiled Ghostscript based on current Git sources. It worked flawlessly in each case.