Processing a color map for B/W printing

[Steerpike]

I'm still in the dark-ages with a b/w Laserjet printer that seems indestructible (old HP laserjet from decades ago); it suits my needs pretty well as I get color prints made online. But often I find myself wanting to print a color map, and the results are terrible. If I just 'reduce color depth' to b/w, the map becomes illegible. I've tried using the 'FineThreshold' Adobe 8BF plugin, and by fine-tuning the 'threshold' to around 200 - 220 range, I can usually produce something barely serviceable but could be better.

Does anyone have any techniques for solving this in IrfanView, better than FineThreshold?

Here's a sample map that you would think would print pretty well in b/w but it's awful - the dashed lines are impossible to get to show without the background blotting out the lettering, even with FineThreshold:

?
Just wondering / hoping if any users have solved this one already! Thanks.

[Bhikkhu Pesala]

Is it a 300 dpi printer? I tried with my 600 dpi printer HP Laserjet 15W, but it was useless. I might be low on toner. I rarely do any printing.

[Steerpike]

Is it a 300 dpi printer? I tried with my 600 dpi printer HP Laserjet 15W, but it was useless. I might be low on toner. I rarely do any printing.

It's rated at 600dpi. It's an HP Laserjet P1505n printer.

The appearance of the print suggests the image is being flattened to b/w first. But I can't find a printer driver setting that lets me explicitly select 'grayscale'. Using FineThreshold does help with many maps, but with this one, as you adjust the setting to get the 'dashed lines' to show, the background also intrudes.

[IrfanUserGuyxyx]

Have you tried image/convert to grayscale in the image menu? Also, ctrl-G calls it.

[Steerpike]

Have you tried image/convert to grayscale in the image menu? Also, ctrl-G calls it.

Definitely tried that, but it comes out the same - like it got converted to hard b/w.

[IrfanUserGuyxyx]

Could you post an example image?

[Steerpike]

Could you post an example image?

The image in my first post in this thread is a great example! I cannot get it to print out well. All I care about in that image is to get the 'dotted lines' (train routes) and the 'duration bubbles' to print. No amount of manipulation can produce a usable printed image.

[IrfanUserGuyxyx]

I tried "image/Effects/Edge Detection" followed by "image/Negative (invert image)/All channels Ctrl+Shift+N" and "image/Decrease Color Depth.../2 Colors (black/white) (1 BPP)".

I got:


Any help?