How could I save on ink when printing this map?

Solution 1:

One Photoshop solution could be to use the "Trace Contour" filter. Admittedly, it works better on images with higher resolution, but I think you won't be able to cut down on ink much further:

Solution 2:

Use draft mode to print- this will reduce colour saturation (or 'blackness') to save ink.

I'd also recommend filling in areas that arn't important in white - in paint.net, using the magic wand, global selection and 26% tolerance cleaned up your image to this in roughly 2 seconds. A little more work by seperating colours into layers (magic wand with same settings, cut and paste into a new layer) and increasing the transparency yielded this.

In short - print in draft mode, fill in white, seperate layers, and increase the transparency of these layers.

Solution 3:

Whilst not technically as good as Soandos's answer (so +1 for the technical one!), I would highly recommend purchasing a cheap Epson printer + fake ink.

Most national computer shops/websites will sell one unique model of printer that you can only buy from them at something stupid like £10/£15/£20, but have ink that can cost twice that, locking you in to that shop... I personally find the cheapest ink I can - usually at £1/£2 per cartridge when bought in bulk and just use that.

Only complaint with the brand I use - Red comes out a little orangey, but, I hardly ever print out proper photographs and would much much rather have a page cost that is a fraction of using real cartridges.

Solution 4:

It is not the simplist things to do, but if you can use GIMP, you can do this in two ways:

1. Use Select -> By Color to select the regions that are that color, and then use Bucket Fill to fill them with whatever color you want.
2. Use the magic wand tool with an appropriate range set (should be very small in your case).

Use this to change colors that you don't want to white.