optimize-pdf does not optimize about asciidoctor-pdf HOT 9 CLOSED

It's highly dependent on which version of gs you have installed. Newer versions do a much better job. And, of course, we may need to tweak the parameters to get more out of it.

One thing to keep in mind is that you should specify an IMAGE_DPI environment variable when calling the script. I keep changing the default, but it's best to be explicit. I found that IMAGE_DPI=150 gives good results (balancing size and quality).

...also, the optimize-pdf script needs to be rewritten in Ruby so it can get packaged in the Gem. We might want to use rghost instead of invoking gs directly.

https://rubygems.org/gems/rghost

Feel free to play around with the script. I'm all ears for recommendations.

from asciidoctor-pdf.

Ghostscript is 9.06 (the latest one on Cygwin), which is about two years old. Setting IMAGE_DPI didn't affect the file size. I'm not a PDF-Ghostscript-DPI expert, so "playing around" with the settings in the script won't help much.

from asciidoctor-pdf.

That's probably the difference. I have Ghostscript 9.14. I remember when writing that script that major changes were made to image optimization around 9.10 and I did see a big difference when I upgraded.

I was able to compile Ghostscript at the time since a package wasn't available for my system back then. If that's possible for you, I encourage you to give it a try.

I looked for other solutions for optimizing PDF, but unfortunately nothing does the job quite like Ghostscript. Eventually, however, I am hoping that whatever logic is going on there can make its way into Prawn so that we can optimize when generating the PDF. Prawn has some optimization flags, but at the time they were corrupting my PDF.

from asciidoctor-pdf.

Btw, I had no idea what I was doing either when writing that script. But I learned through trial and error and this reference page:

http://ghostscript.com/doc/current/Ps2pdf.htm

from asciidoctor-pdf.

I tried the Windows version of 9.14 with the script. Now the resulting PDF is of the same size as the original one. At least the size doesn't double anymore. I guess I leave the PDF optimizations for now as they are.

from asciidoctor-pdf.

Actually, that's a good point...when to use optimize-pdf. The reason I was using it...the reason I created it...is because my original PDF was 20MB. In that case, I saw a major decrease in size. Below a certain size, you might end up with a larger PDF as you have observed. I'd say if the PDF is below 5MB, then just keep it as is. A good tip for the guide.

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The action here is that if the optimized file is not smaller than the original, don't overwrite the file. There's nothing I can do about Ghostscript not actually making the file smaller. There's no guarantee of that.

from asciidoctor-pdf.

There are two solutions to this problem. In the next release, you'll be able to activate the optimizer and control the quality using the optimize attribute. For example, -a optimize=screen may, in fact, decrease the size.

The other solution is to use hexapdf as documented in the README.

Beyond that, this is really outside the scope of what Asciidoctor PDF can do.

from asciidoctor-pdf.

I'm going to close as a duplicate since #535 will address this in part, and using hexapdf as an alternative has already been documented.

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