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lokiie1984
04-21-2013, 05:41 PM
Is there a way to take a specific color in a picture and change it to a different color? Without losing all the details?

For example in the picture below i want to make it have more desert colors. Remove the green and replace it with a tan and then go darker as the elevation goes up. Or maybe lighter, not sure on what colors i want yet. Seems like there should be a way but I'm not even sure what terms to use to search for it.

53817

(Picture was made using Geocontrol2)

Thanks

jturner
04-21-2013, 06:52 PM
Hello lokiie, I've just learnt how to do something similar myself, so maybe it will work for you.
1. Click "Select by Colour" tool
2. In the options window below, change Threshold to about 90
3. Click somewhere green in your image
4. Create a new transparent layer and call it 'Colour Overlay'.
5. Select a deserty colour
6. Drag the colour across to your marching ants
7. In the Layers window, click Mode and select Colour.
8. Play around with different colours in steps 5 and 6 until you're happy, then right click on 'Colour Overlay' in the layers window and click Merge Down.
There might be other easier ways to do it, and I'd be interested to find out if so.

RobA
04-21-2013, 07:46 PM
The rotate colour command might also work in this case:
8.25.*Rotate Colors (http://docs.gimp.org/en/plug-in-rotate-colormap.html)

-RobA>

lokiie1984
04-22-2013, 01:08 AM
Thanks for the tips. The rotate colors worked a little bit but it didnt give me much control over the shade of color. Jturner's method seemed to work the best.

Jaxilon
04-27-2013, 05:17 PM
I usually use a color layer and a mask to alter those types of things. Trying to fiddle the actual colors on the layer seems to always get tedious.

It helps if you get into the habit of putting your colored areas on different layers as well. Then you can colorize and adjust that layer only to get what you want. In other words, have your black and white drawing and then have the coloration of land, sea, whatever all on separate layers. Use masks to have the colors only effect the areas you want.

Hopefully, that makes sense. If not, I can put together a better explanation. It's pretty much what Jturner is saying I think except adding a mask into the equation. If you don't do masks there is a great tutorial on them here (http://www.cartographersguild.com/tutorials-how/3143-award-winner-explanation-layer-masks-gimp-ps.html).

lokiie1984
04-27-2013, 09:03 PM
One thing i found that helps with recoloring is to desaturate it first. Other wise the colors below seem to react with the new color. When i was trying to change that green, it ended up looking neon.

Of course now I'm trying completely different take on the map so it doesn't matter but its all still good info for later gimp use.

Now i'm off to sacrifice a goat in the hopes that the Wilbur gods will grant me a volcano. (I have spent more time trying to make this island volcano then i have on anything else lol.)

Jaxilon
04-28-2013, 01:13 AM
They can be a challenge. I've never taken the time to figure out Wilbur but some of the guys around here are really good at using it. Not to mention the developer who's poking around in here somewhere :)

lokiie1984
04-28-2013, 01:54 AM
Wilbur is a pretty neat tool for maps, i just wish it came with a nice thick manual lol. I did manage to get an alright volcano, now I'm trying to rework my main land mass so its not so flat. Trying to see if i cant add the basins into my heightmap so i can make them into lakes too. Course now my mountains tower over the land and when i try to erode them to make em fit better it washes away all my nice hills. I think that's how my original try at all this ended up so flat.

One day i will have a good map to work with, i may die of old age first though. In which case i will leave it to my non existent kids to make.