Photo Compositing with The GIMP: Part 2

November 2009

Adding Realism to the Image

As of the current state of our image, it’s almost done.  But we could still do something about adding even more believability to it than just our “2-d object on hand” setup here, right? First thing to consider is that photographed scenes aren’t actually as clean-looking as they are and as compared to common CGish images.  Just to break this cleanliness apart, let’s add in a simple cloud noise to our heart.  If that still doesn’t work for you, you could go ahead and paint over some details like cracks, dirt, etc.  This is to simulate the wear and tear effect that is always present everywhere we look at.

To add this texture, let’s first create a new transparent layer to work on and let’s call it “texture” or something much more meaningful to you and easier to remember.  This will be the layer that will hold the cloud texture to use for the heart.  After adding this new layer, right click on the image window and select Filters > Render > Clouds > Solid Noise (as seen in the screenshot below).

Photo Compositing with The GIMP

Creating the Texture

Again, a pop-up window will appear wherein you can input values for the noise. This will entirely depend on your preference.  This fill then fill-up the entire layer with the cloud noise texture that we’ll use as overlay image for the heart later on.  Check the screenshot below for my settings.

Photo Compositing with The GIMP

Cloud Noise Options

You’ll notice now that what we see is just pure texture which is not what really wanted.  Instead we’ll use it as an overlay effect on top of our layer stack.  Let’s do this by changing the layer mode from Normal to Overlay then let’s adjust the opacity of the texture layer to something relevant and subtle.

Photo Compositing with The GIMP

Texture Overlay

However, we notice that the texture is affecting everything in our image including the hand and the cloth.  But we only want the heart to be affected by the texture.  We can do this in a couple of ways: the easiest would be to use the Eraser Tool to erase portions of the texture layer so we only leave the part of the heart, but doing this though will add more layers of undo levels everytime we stroke our eraser. What if we wanted to only have this single layer to work on yet have the flexibility as though we were switching from two layers (an original and a duplicate).  With this in mind, I think it’s time we use Layer Masks for more flexibility over our layer management.

To apply our masking, let’s first create a selection to exclude the other parts of the image other than the heart, do this by right clicking on the heart layer then selecting Alpha to Selection. What this will do is select regions of the layer where it is opaque, in this case we’re only selecting the heart shape.

Photo Compositing with The GIMP

Creating the Heart Selection

Now with the heart shape selection active, let’s go back and activate our layer texture from which we’ll be creating our layer mask on (be sure that your selection is still active or else it will defeat the purpose of even creating it in the first place).  Right click on the texture layer and select Add Layer Mask (see screenshot).

Photo Compositing with The GIMP

Creating a Layer Mask

With the pop-up window that appears, select Black (full transparency) then press Add.  You’ll then notice that the effects the texture has are gone now, that’s because we filled the whole layer mask up with color black (which means full mask), making everything in the layer appear as nothing.  But since we want the current heart selection to have an effect on the layer, we’ll do the reverse instead, by filling up the selection with color white (#FFFFFF). Do this by selecting the layer mask, and not the layer itself, then use the Bucket Fill Tool to fill the selection with white.  Now we’ll notice the effects take place.

Photo Compositing with The GIMP

Applying the Layer Mask


We’re only one step close to finishing the compositing here (yes, finally!). If we’re lucky enough to have gotten this far and not got bored the hell out of us, there’s one thing believably missing in our composition here, and that is the way the two fingers seem to be blocked by the heart (which shouldn’t be).  We should instead see the fingers somehow embrace parts of the heart.

With all of our settings for the heart (highlights, shadows, and textures) done, we can now merge all of this into only one layer so we would only be working on one instead of applying the same effect over the rest of the layers which will eventually become a burden.  To merge all of the heart layers, let’s first turn off the visibility of the photograph layer, then right click on any of the layers comprising the heart then choose Merge Visible Layers then choose Expanded as Necessary.  This will then compress all of the heart layers into a single layer which would be very handy for our proceeding steps.

Photo Compositing with The GIMP

Merging Visible Layers


You’ll notice on our Layers Window that we only have two layers now to work on (actually one, just the heart layer).  All we got to do now is to select portions of the heart that is supposed to be blocked by the ring finger and the pinky finger.  Let’s go ahead and bring the visibility back on our photograph to actually see the image we’re working on.  Since it’s hard to judge the shape of the fingers that’s being cut by the heart view, it’s a good idea to lower down temporarily the opacity of our heart layer just so we could see the image underneath it.

Photo Compositing with The GIMP
Lowering Down the Heart Layer Opacity

Now that’s looking better.  We can now see the underlying curves and geometry to base our selection from.  Let’s just go straight on and use the Paths Tool to outline parts of the ring finger and the pinky finger.  Then afterwards create a selection out of the path outline we’ve made by pressing Enter on your keyboard or clicking Selection From Path from the Toolbox Options Window.

Photo Compositing with The GIMP
Creating the Selection from Paths

We can use the same technique that we’ve used with masks to delete this portion of the image or you can just go ahead and press delete on your keyboard to remove this part of the selection (make sure you have the heart layer as the active layer).

Photo Compositing with The GIMP
Masking the Selection

Then finally (again?!), add some shadows to better enhance the relationship between the fingers elevation and the heart.  Use the same technique that we used all throughout this article.

Photo Compositing with The GIMP
Final Composited Image


Photo Compositing with The GIMP
Final Composited Image – Black and White


So that’s about it! Hope you enjoyed this little (uhhhh rather huge) article on compositing with GIMP. See you next time!


I want to thank you for reaching up to this point of my article and I do hope you learned a lot from this walkthrough that I did. To review over what has happened from the beginning of this article, we tackled selection feathering, shadowing, basic image manipulation and color adjustment, basic texturing, and the usefulness of the Bezier or paths to create irregular selections.

If you have any comments, suggestions, recommendations, or you just want to say hi, feel free to send me an email at You can also check me via Twitter on and my regular blog at .Happy GIMPing!

You've been reading and excerpt of:

Blender 3D 2.49 Incredible Machines

Explore Title
comments powered by Disqus