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Discussion: Double Sided Map PDF - Color Issue

in: Orienteering; General

Apr 27, 2023 3:25 PM # 
I'm giving participants a double sided map for an event this weekend. I have discovered, to my chagrin, that when I take the separate front and back map .pdfs (which print nicely separately, ergo, not an OCAD output problem) and merge them to a single, double-sided .pdf, the result is noticeably lighter than the originals. I also note that the file size decrease from abt 14MB each to only 1.5MB or so in the combined file.

- Have you experienced this, and did you find a way/set of settings to directly print double sided .pdfs without degradation of color (other than printing side 1 and running those sheets back through to print side 2 on the back)?

Apr 27, 2023 5:00 PM # 
Or just print them separately and put two pieces of paper in the map case?
Apr 27, 2023 6:39 PM # 
If you're using Adobe, default settings for merging PDFs shrinks them, you could try adjusting the setting.
Apr 27, 2023 8:58 PM # 
Map case... how quaint!
Apr 28, 2023 12:03 AM # 
QPDF works well for this. Download and install qpdf-11.3.0-msvc64.exe from here, or other versions as needed, or "apt install qpdf" on WSL 2 Ubuntu or other Debian-ish Linux things.

The PDF code inside the doc from the following is unaltered after joining, and it's very very fast:

"\Program Files\qpdf 11.3.0\bin\qpdf.exe" --empty --pages map_front.pdf map_back.pdf -- map_combined.pdf

It's amazing what some products waste their time on when "doing things" with PDFs, especially concatenations like this. It's all text in there!
Apr 28, 2023 12:16 AM # 
My club uses the quaint JJ solution. The main reason is the potential of the image on the reverse side showing through. Short of printing on a very heavy “cover” stock, try looking at the back of any one-sided map held up to a light or computer screen, and you’ll be able to at least see shading differences where there is print on the other side. At most printers, the cost difference between 1 sheet double sided and two sheets single sided is negligible.

I wonder if possibly the color lightening might not be in the PDF, but perhaps be a “smart” printer setting that is attempting to reduce the “bleed through” effect, especially if the printer is sophisticated enough to be set for different paper weights. If the printer has settings for the paper weight, you might print a test copy on 80 or 100 pound cover stock and see if it still comes out lighter. The “smarter” that printers have become, the more they mess with stuff that you don’t want them to mess with!
Apr 28, 2023 12:22 AM # 
The “smarter” that printers have become, the more they mess with stuff that you don’t want them to mess with!

Apr 28, 2023 3:30 AM # 
Can't help thinking of Talkie the Toaster from Red Dwarf.
Apr 30, 2023 7:14 PM # 
@mikem - Thanks! You are correct, the reverse sides do show through ever so slightly when held face down (and badly with light from behind), but I figured that was a fair price to pay for having one less set of paper to manage (and one less piece of paper for runners to deal with in a breeze).

Your message got me to do a re-examination of the situation. I'd been certain that the merged pdfs were visibly lighter on-screen, but I was wrong (printing only side 2 of the two sided file came out on paper as nicely as did printing the pre-merged side 2).

My (fairly new...) Epson WP-4380 does in fact have stuff-that-I-didn't-want-to-mess-with :-) in the form of a "Print Density" sub-menu. The default print density value is -30%. I set that to 0% and set the between-sides drying time to 15secs, and the result was excellent.

Further to your point, saving paper is the least important dollar-parameter. Home printing, I can get 28lb (still not thick enough to block shine-through) paper locally at $0.05/page, my printer uses abt $0.19 of ink per side, and OUSA rules-spec map cases run $0.13 each. Cheap 20lb paper (sub OUSA spec) can be bought for $0.01/page.
Apr 30, 2023 8:21 PM # 
The paper quality is important for the final result. I use 32lb paper when I print good quality maps at home.
May 1, 2023 6:28 AM # 
We've gone to Teslin 115 for everything. There are some issues, but show-thru is not one of them. And double-sided maps are more and more common round here.

This discussion thread is closed.