Sea Parchment

[Sam Conifer]

Gimp knowledge:
I'm a Gimp newb but I really like it a lot. It is only today when I realized that a Gimp registry exists where others post scripts they have created for others to download and use.

Mapping Objectives:
I do not want to just create cool looking maps. What I want to do is learn processes that will help me get an idea down on paper quickly so I spend little time creating good looking maps. Since time is so important to what I want to accomplish I try to shy away from manual painting as much as I can and other potentially time consuming techniques. Time spent learning is okay though.

Over the last three or four days I have spent 16 to 20 hours trying to get as close as I can to creating what I am now thinking of as a Sea Parchment. The purpose of the Sea Parchment is to cover the area of the oceans of a map and I suppose it could even have an effect on land as well. I want this sea parchment to look a bit like a mix of watercolors, of blues, grays, and reds like something out of An American Tale or The Secret of NIMH. I have found though my endeavors over the last few days that the plasma filter works very well, but it doesn't seem to get me close enough to what I want. Here is a quick example of a general plasma result:
http://www.cartographersguild.com/at...3&d=1298962498

What I really like about it is that it seems to randomly splash colors in the pattern that I am looking for, and not for example like a noise filter where the colors are not grouped together. What I do not like about it is that there really is no control over what the colors are. I don't want those bright greens, yellows, and purples. If I could only control the colors I am sure I could make this work.

Following that thought I rummaged through the net until I found the Gimp registry and there found plasma2. Last night I installed that and was happy to find that it allowed the option to use a gradient for a color source, even of course a custom gradient. After tweaking this for many hours the closest I have come to what I want is this:
http://www.cartographersguild.com/at...4&d=1298962520

I had thought that working with a gradient was the perfect solution, but I found that while it solved the problem of color selection it presented more problems. One of these problems is that the colors do not appear to be as randomly splashed as in the basic plasma. They must transition from one color to the next which means that one particular color will always be bordered by the same 2 other colors. Another problem that the gradient presents is that with every introduction of a new color the image shows harsher blends between the changing colors.

I have messed around with the gradient, made compromises on colors - I would have wanted a bit more vivacity of color though not too much, tried changing different settings in plasma2, tried different color adjustments, but that haunting water color feel I am going for still eludes me. I know it must not be easy to imagine the visual I am trying to describe with words, but if you can and have any suggestions on how I might get this thing right, I would love to hear them.

Latest context example:
http://www.cartographersguild.com/at...7&d=1298968290

[ravells]

Have you tried using the smudge brush (or whatever the equivalent is in Gimp)? It's good for wet in wet watercolour effects.

[tilt]

I don't use Gimp, but if I had the first plasma image in photoshop and wanted to use it as a sea - I'd desaturate it and then change the hue (coloring) it to blue after. Don't know if you can do that in Gimp however...

[RobA]

I don't use Gimp, but if I had the first plasma image in photoshop and wanted to use it as a sea - I'd desaturate it and then change the hue (coloring) it to blue after. Don't know if you can do that in Gimp however...

In one step with the colourize filter (It desaturates first). More control if you use the channel mixer.

-Rob A>

[Sam Conifer]

Thanks for the suggestions. I tried colorize and began to think that if I could just remove the darkest and lightest colors I could get a good result. So I experimented with Color to Alpha. I would make a plasma layer, then use colorize to make it a single hue - a blue for example, then use Color to Alpha to take out the black, then use Color to Alpha again to take out the white, then make a new layer and repeat the process with another hue - red for example.
http://www.cartographersguild.com/at...0&d=1299003661
It seemed to work very well until I wanted to get a darker color in. That technique doesn't allow dark colors, and black is too dark to not filter out. Since the Color to Alpha doesn't seem to have a threshold control or whatever its called, there doesn't seem to be much adjustment for that. I tried union select and delete, but that seems to either blur the image too much if feather is used or remove too much of the... inner color detail?

Anyway, using the channel mixer:
http://www.cartographersguild.com/at...1&d=1299003685
Everything seems to look great. I had never used the channel mixer before, but this I think is definitely my favorite way to do this.