View Full Version : Making water with soft edge in Gimp

joćo paulo
03-29-2009, 06:36 PM
The first step is open GIMP and create a new image,with the brush tool, paint a blue patch that will serve as the basis for our tutorial.


joćo paulo
03-29-2009, 06:45 PM
Now we have this body of water, we can begin the work.
In the menu "filters" select "blur">"gaussian blur" the level it in this case is 70 pixels.


joćo paulo
03-29-2009, 06:49 PM
Use the menu "Colors"> "posterize" changed for 10 levels.


joćo paulo
03-29-2009, 06:53 PM
In the same menu "Colors"> "brightness-contrast" changed to 6 and 23 respectively.


joćo paulo
03-29-2009, 06:56 PM
Again use the "gaussian blur" filter this time for 12 pixels.


joćo paulo
03-29-2009, 06:59 PM
In the "layers window" create a new layer and add an "alpha channel" to it.


joćo paulo
03-29-2009, 07:05 PM
Paint or load a terrain to this new layer.
Now using the "eraser tool", erase the region over the water(in the new layer).


joćo paulo
03-29-2009, 07:09 PM
The end result of our work should be more or less like this:


Please feel welcome to correct any errors I have committed on this tutorial.

03-29-2009, 11:32 PM
That's a nice looking water.

Steel General
03-30-2009, 07:26 AM
Lookin' good JP!

03-30-2009, 08:58 AM
Hello, joćo paulo.

This will be a quite useful tutorial for creating water in GIMP. Thank you for writing it and sharing it.


I have created a PDF document of this tutorial and have attached it to this message.





joćo paulo
03-30-2009, 09:10 AM
Thanks for the PDF version and the words Vandy :)

03-30-2009, 05:28 PM
Thanks Vandy, our resident scribe. I always like to download something and work on it with the browser closed.

03-31-2009, 02:20 PM
One suggestion on the posterization technique.

Gimp's posterize "is designed to intelligently weigh the pixel colors of the selection or active layer and reduce the number of colors while maintaining a semblance of the original image characteristics" (from the gimp docs).

What is not explicitly mentioned is that each channel of the image is separately analyzed. This means for a posterize setting of 3, you will end up with 3 levels each of R, G, and B, or 27 colours.

This works nicely for some images:

But not so well for single colour gradients (like the blur in this tutorial creates) that are not pure R, G, or B

I found a tutorial on the web that described using an index mode conversion to create a different posterized version of an image. Attached is a script that implements this (Shows up under colours->Posterize Indexed...). Note that the slider here is the number of colours, not channel levels, so a comparable setting to posterize level 3 would be 27 colours.

Here is a typical gradient, posterized and with my posterize indexed script:

But it really depends on the source image, as this might not be what you expect from the colourwheel using poster indexed (to 27 colours):

-Rob A>

joćo paulo
03-31-2009, 06:42 PM
Thanks for the improvements and the very useful script rob.