Gimp Tutorial Polished Stone

Introduction

Stone We shall now go out to the nature (the big blue room, you know), pick up a decent looking little stone and have it polished at the jewelley in the city. Then we take a nice picture of it :-).

This tutorial was written using Gimp 1.2.2 on a SuSE 7.3 system after I did several of those stones for a design project at work.

How To Do It

New Image

First lets create a new image, say of size 256x256 with a white background and open the layers menu. Create a new transparent layer by hitting C-n in the layers dialog. Name it "stone shape".

Create The Basic Shape

Shape1 First we use the ellipse too (e) to create a nice flat shape. Then, to make it look more natural we change that shape a little: Use Image-> Select-> To Path to create a Path from your elliptic selection and go to the Path-tab in the layers dialog (maybe you want to rename the path, here I called it "stone basic shape"). Then move some of the points of the path using Control-left mouse button and maybe change the smoothing of them by just dragging the handles with the left mouse button. Click in the middle to get a selection from that path.
Shape
two Go back to the layers-tab, select the bucket-fill tool (Shift-B) and fill the shape with solid black. Duplicate the layer twice and name the two new ones "stone shadow" and "stone texture". Make the shape and shadow layers invisible by clicking on the little eye-icon in the layers dialog and select the texture layer.

Creating a Stoneish Texture

Texture1 First remove the selection using Control-Shift-a. Make sure that the "Keep Transp." button in the layers dialog is checked and select Image->Filter->Render->Clouds->Plasma. In the upcoming dialog set the turbulence to any value (I found that higher values (and thus more filigrane textures are better for stones in the front, whereas lower values are better for stones somewhat more to the background).

Use Image->Image->Colors->Desaturate and maybe adjust some aspects of the texture using, for example, the curves-tool, the levels-tool or maybe some contrast settings. I used Image->Image->Colors->Auto->Stretch Contrast here.

Blur the texture with a Gaussian Blur and a radius of 1 in both directions (the screenshot is not yet blurred).


Give It Some Depth

Gradient1 We will use a very simple approach by just adding some darkness to the lower part of the stone. Therefore create a new transparent layer and name it "stone gradient". Get the old stored selection from the path and select the gradient (or Blend) tool (l). By double-clicking the gradient icon in the toolbox you get the tool options where you can set the gradient to "FG to transparent". Now apply it to the picture starting a bit below the selection and ending somewhere close to the middle of it (dragging the left mouse button is the game...) so that it looks somewhat like the one in the screenshot (where I removed the visibility of the texture layer for teaching purpose)


Gradient2 With the texture layer back again and the selection remove (Control-Shift-a) it already looks a littlebit like a stone. In this case I find the texture to be too dark so I use the Curves tool (Image->Image->Colors->Curves) to lighten it up.


Polish By Highlight

Highlight1 Now to achieve the illusion of a polished surface we paint some little highlight on it that shouldn't be too blurry.

Select the paintbrush (p) and make the foreground color white. Choose the circle fuzzy 05 brush. Create a new transparent layer ("stone highlight") and paint one of those typical shiny highlights you always see on such surfaces (in the screenshot I zoomed in for accuracy).


Highlight2 Blur it using Gaussian Blur at radius 1 (I'm not sure whether you have to blur it at all)

Add The Shadow

Shadow Now we get back to the shadow layer we created earlier. First make it visible (you know... the eye-con ;-) and then blur it with a radius of some 15. Set it's Opacity in the layers dialog to ca. 45 and move (m, be sure to really pick the layer you want to move) the layer a few pixels to the right and down.


Finish

Now save the XCF file and then save it as (say) PNG, Gimp will ask you to flatten (that is merge the layers) the image. Well and since we always named the layers and paths with a "stone" in it you can now create a second stone and call those layers "stone2-something". Feel free to download the XCF file and play around with it.