|Getting Started with The GIMP: an informal tutorial: CSLUG and Rock Eagle Presentations, October 2002|
|Prev||Chapter 4. Tiles||Next|
Since I'm most familiar with making tiles, that's the subject we're going to discuss in this chapter. When I say "tile," I mean an image that matches up with itself along the edges so you can use it as a seamless repeating background. I like to make tiles for use as computer screen backgrounds - that means rather less visual subtlety than you might use for a web page background, but most of the same principles apply.
I generally use the GIMP's extensive selection of filters to generate images. That's what I'll be covering in this chapter, as using drawing tools was covered in the GIMP tutorial mentioned above, "Easy Patterns."
Start a new image. I'll be working at 400x400 pixels in size, but the choice is yours. As always, remember that the bigger the image is, the more space it takes up.
Now might be a good time to mention the wonders of tear-off menus. There are certain menus that I end up using a great deal, and it becomes tedious to keep right-clicking on the image and then navigating the menu system to the item I want only to have to repeat the process almost immediately. The authors of the GIMP have come up with a fairly nice solution to this: right-click on the image, navigate to the menu you want to use (I would suggest "Filters") and notice at the very top of the menu there's a dashed line. If you put your pointer over that, you'll notice that it becomes highlighted like any other menu item. Click on it, and the menu becomes its own window that you can position anywhere you want.
The Filter menu, after it's torn off.
I recommend creating most new material for tiles on their own layers - particularly when you're working with the "Render" menu item, as it overwrites the current layer. So as a first step, create a new layer. Now click on "Render" in the Filters menu, and select "Clouds -> Solid Noise ..." In the dialogue box that appears, click the "Tileable" checkbox. This is obviously a really nice feature to have if you're working on tiles, and it's available in a few of the dialogue boxes we'll be working with. I'm going to click the "Turbulent" checkbox as well because I like the effect. If you're curious, you can create a second layer with "Turbulent" toggled the other way so you can see what the two do differently. The "Random Seed" setting is interesting too: by default it's set to "1", and if you come back to this dialogue later, you'll get the same pattern again with the number set on the same time. If you want to get a different pattern each time, click the "Time" button and you'll get a (mostly) random number chosen every time you generate a Noise picture.
The "Solid Noise" dialogue box.
To verify that the material you've created is tileable (a good practice - I've spent a lot of work on some images only to find I did something non-tileable several steps back and I had to discard the image) right-click on the image, select the "Image -> Transforms -> Offset ..." item. In the dialogue box that appears, select the "Offset by (x/2), (y/2)" button. You'll notice that it puts 200 in the X box and 200 in the Y box (if you're working with a 400 by 400 image). Say "OK." The image is offset by 50% in both directions, and you should still see a seamless image. If you don't, go back and check that you had the "Tileable" button switched on. Remember to perform this check occasionally. You can now click CTRL-Z to reset the image to its original position. In fact, I'd recommend this - not because it's necessary now, but if you make tiles much you'll find yourself working with layers that match up in a particular position, and offsetting one will ruin the image. So hitting CTRL-Z to undo the change is good practice.
Make a new layer. In the new layer, use "Filters -> Render -> Clouds -> Plasma ..." to generate some colours to add to this black and white image. Now hit CTRL-SHIFT-O (the keyboard equivalent of the Offset command we just used) and offset by x/2, y/2. You'll immediately see that Plasma doesn't render a tileable image. Use CTRL-Z to set the image back where it was, and now select "Filters -> Map -> Make Seamless." I'm not too crazy about this filter, but it does work. You may notice bands of colour half way along each edge of the image, and that's the price you pay for "Make Seamless." Finally, go to your "Layers, Channels & Paths" dialogue box and set the mode of the plasma layer to "Overlay." You now have a tileable image that you can save. Try setting the plasma layer's mode to other modes, and see how they look too.
The final form of the tiled image.
The tile we've generated isn't that exciting, but in combination with the previously mentioned GIMP tutorials you should be on your way to creating something much better.
If you're interested in making tiles, I would highly recommend that you download the Plasma2 plugin from the GIMP plugin registry at http://registry.gimp.org/. If you have the Windows version of the GIMP, it's already included, but most Linux users will have to download it for themselves.