Tutorial: Kaleidoscopic Reflections With GIMP

Start by opening the image you want to mirror. You should pick an image with interesting colors or identifiable small features. In this case, the eye is a small feature and the green-brown-orange color scheme is pleasing.

Next, crop out a square portion of the image. You probably want an area which contains the interesting features and colors but not too much of any one of them. Technically, you don't have to work with a square area, but it's much, much easier if you do.

Use the width/height settings on the Crop Dialog box to make sure that you have a square.

Create a new layer in the foreground color. Make the new layer twice the size of the old layer. In this case, since we cropped the image to 800x800, we make the new layer 1600x1600.

Then, duplicate the 'New Layer'.

Rotate the 'New Layer' (not the copy) -45.00 degrees. Use the rotation dialog box to get exactly -45.00 degrees and to center the rotation at (0,0).

Rotate the 'New Layer copy' -22.50 degrees centered at (0,0).

Select 'Alpha To Selection' from the 'New Layer copy' in the Layers dialog box.

Invert the selection.

Delete the 'New Layer copy'.

Cut (Ctrl+X) the inverted selection from the 'New Layer'. Then, do 'Layer to Image Size' on the 'New Layer'. And, set the opacity of the 'New Layer' to 50%.

At this point, you may wish to play around a bit to get something prettier under the black section. For my purposes, I'm just going to rotate the 'Background' that I have 90-degrees clockwise.

You should now have something like this.

You may prefer to copy in the original full-sized image to get exactly what you want under the triangle. If you do, make sure you do a 'Layer to Image Size' and merge it with the 'Background' layer or the rest of this tutorial is going to be confusing.... 8^)

Do 'Alpha To Selection' on 'New Layer'.

Now, do 'Add Layer Mask' on the 'Background' initializing it to 'Selection'.

Clear the selection (Ctrl+Shift+A). Delete the 'New Layer'. Apply the layer mask. This is our wedge.

For good measure, do 'Layer to Image Size'. We're going to start rotating and reflecting things and we want to be sure of exactly what we're moving.

Rotate 'Background copy' 45-degrees centered at (0,0).

Merge the layers together. Again, do 'Layer to Image Size' just to be safe. You should now have one layer which contains two copies of the wedge that had been under our triangle. There should be two empty wedges in the picture, too.

Duplicate the layer. Rotate the copy 90-degrees clockwise. This looks kinda funky, but we'll fix it in a moment.

Mirror the copy horizontally. Merge the layers. Do 'Layer to Image Size' just to be safe.

At this point, there are probably some gaps along the seams. The most obvious gap here is the diagonal line in the upper-left. We're going to fix that by duplicating the layer, merging the duplicate onto a neutral background, blurring the merged duplicate, putting that blurred version below this layer, and then flattening the image.

Duplicate the layer.

Between the two layers, make a grey layer. You can do this by setting the foreground color to grey and creating a layer initialized to the 'Foreground color'. Or, you can make a layer however you like, select it all, and fill it with a grey. It doesn't matter.

Merge the copy and the grey layer. Blur it... say maybe a Gaussian of radius 5.

Move the 'New Layer copy' down below the 'Background' layer. Then, flatten the image using 'Flatten Image' from the 'Image' menu.

Now, we just have to mirror this four times to get our 16-fold symmetry.

Scale the image down by a factor of two in each direction. Our image is 800x800, so we're going to make it down to 400x400. I've selected 'Cubic' scaling because that's almost always the best thing to do. It certainly is the best for this image.

To make things easier below, we're going to rotate the image 180-degrees. We're going to resize our canvas and we're going to want this tile to be at the upper-left of the larger canvas.

Now, resize the canvas back up to twice its current size. We had scaled down to 400x400, so we're going to make the canvas 800x800. And, we want to leave the offset at (0,0).

If we were feeling cunning, we could have skipped the 180-degree rotation and offset by (400,400) and still be fine. But, I usually prefer to keep to a minimum the number of times that I have to actually know the image size.

Duplicate the layer. Do 'Layer to Image Size' on the duplicate. Then, mirror the layer horizontally.

Now, merge the layers together.

If you don't do the 'Layer to Image Size' here, you will end up with both layers in the same spot in the upper-left corner.

Again, duplicate the layer. Do 'Layer to Image Size' on the copy. Now, mirror the copy vertically.

Now, flatten the image.

This is the final image. In this case, things worked out okay for us. But, for more complicated angles or small pictures, you may find that there are problems at the edges during the final mirrorings here. You may find it useful to hold off on the whole "duplicate, merge with neutral layer, blur, move blur to bottom, flatten image" process until the very end. That way, all of the seams get filled with very close to the right thing.

For more fun, repeat the process another time or two. You may also like to use 'Offset' in the 'Layer' menu to offset the layer, with wrap around, by (x/2,y/2) before starting the next mirroring pass. (Or, just skip the 180-degree rotation after the scaling.)

Here is the image after three 16-fold mirroring passes without offsetting the image at all. You can get pretty quick with the process after only a few passes. So, enjoy.

Because this looks like ugly linoleum, I scaled them down to 200x200, bevelled them, and then tiled them. Here is the best of those. Your mileage may vary. Have fun. I hope this tutorial was helpful.