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printing colored topo maps in black and white
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Dont Wantto
(longhiker) - F
printing colored topo maps in black and white on 05/21/2010 17:07:26 MDT Print View

I have USGS Topos in electronic format as PDF and TIFF documents (from the USGS website.. free!). I want to print them on my black and white printer.

Does anyone with experience with software like Photoshop know how best to convert it to a simple black and white image, so that only the contour lines show up in black?

With a generic convert, I find that the background colors like green shows up grey and can barely be distinguished from the contour lines.. the map looks awful..

I essentially want to throw away a lot of data from these colored topos and get just the contour lines and names of mountains..

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: printing colored topo maps in black and white on 05/21/2010 21:21:10 MDT Print View

Change data type from 24-bit Colour to B&W.
Prints well on a plain laser printer.


Rod Lawlor
(Rod_Lawlor) - MLife

Locale: Australia
Where? on 05/21/2010 21:53:39 MDT Print View

Sorry Roger,

Do I do this in the file, or during the printing process?


Dont Wantto
(longhiker) - F
too much grey on 05/21/2010 22:03:59 MDT Print View

Hey Roger,

I assume you mean this as a printing option -- I'm afraid it makes the map pretty grey overall. Still readable but not great.

After posting this, I tried fooling around with the 'Replace Color' option in Photoshop (GIMP and other free alternatives to Photoshop must have a similar option). This allows you to pick a color on the map and replace all instances of that color with something else.

I tried doing this with:

Green (trees) -> White

Cyan (rivers & water bodies) -> Black

Reddish brown (contours) -> Black

It wasn't perfect but I thought it might work if I were more experienced with this stuff. The main problems were:

1. (obvious) there are several shades of green for trees for example.. must replace each.

2. (biggest problem) the labels on the map (eg. peak names, trail names) are in black but often small and done with thin lines and are not very readable after converting to B&W.

Anyway, at some point this gets to be more trouble than it is worth. I just have a photocopy of a map a ranger at RMNP made for me -- crisp black contours on bright white background.. no shading of any sort.. and I'm trying to recreate that.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Where? on 05/22/2010 01:51:58 MDT Print View

Hi Rod and Dont

Very definitely, as Dont suggests, with an edit program like Photoshop or Gimp (free).

Yes, you have to select colours like the green for forest and replace with white. The edit programs usually let you select a range of colour for generic replacement.

If you are having trouble with the small print, that is partly due to the original printing process, but can sometimes be improved by scanning at a higher resolution. If you want to be really fancy you can try a limited amount of blurring and thresholding to 'join the dots', but that is a bit messy.

As you may gather, I do this myself a lot. My topo maps stay at home: I only carry printed copies or photocopies in the field.


Edited by rcaffin on 05/22/2010 01:56:33 MDT.