In this tutorial, I’ll be showing you an easy way to create textured, realistic wall graphics using GIMP! The result not only contains realistic shading and texture, but also allows other elements such as vegetation to realistically cover up the graphic. This method uses a built-in filter – so no external plugins required. Let’s get started.
Step 1: Open Your Photo and Graphic
To start off this tutorial, I’ll need to import the photo of a wall where I’d like to place my graphic. I used a free stock photo from Pixabay that you can download here if you’d like to follow along.
I’m also using the GIMP Wilbur logo, which you can download from my website here.
Once you’ve downloaded the photo and graphic, open GIMP. I’ll be using GIMP 2.10.18 for this tutorial – I recommend using whatever the current version is currently.
To open your photo, go to File>Open (shown in the image above).
Navigate to the location on your computer where you downloaded the image. In my case, I downloaded it to the Downloads folder on my D:/ drive. Once I’ve located the image file, I’ll click on it (red arrow in the image above) to select it (this should generate a preview over on the right-hand side of the “Open Image” dialogue box – blue arrow). Then, I’ll click the “Open” button (green arrow). This will open my image as a new composition into GIMP.
Next, I’ll open my graphic into the composition as a new layer. To do this, I’ll go to File>Open As Layers (shown in the image above).
I’ll once again navigate to the location on my computer where the graphic is stored and will click on the file name once I locate it (red arrow in the image above). I’ll click “Open” to open the graphic into my composition as a new layer (green arrow).
Step 2: Scale and Position Your Graphic
Now that I have my image open with the graphic place on top of it, I can scale the graphic and position it. I can accomplish all of this by simply using the scale tool.
In GIMP 2.10.18 and newer, the tools are grouped essentially by category. So, in my toolbox, I’ll click and hold my mouse on the transform tool group (it should have the unified transform tool by default – red arrow in the image above). I’ll then click on the “Scale” tool (green arrow). I can also simply hit shift+s on my keyboard to access this tool via the shortcut key.
Click on the graphic with your scale tool (green arrow in the above image) to activate the tool (make sure your graphic layer is the active layer in the layers panel so that you scale the correct layer). Next, click and drag any of the transform handle in the corner of the graphic (red arrow) and drag inwards towards the center.
While you are dragging, hold the ctrl key so that all four corners of the graphic layer scale inwards towards the center (as shown in the image above). Release your mouse once you have scaled the graphic up or down to your liking (drag the scale tool away from center to scale the graphic up).
If you want to reposition your graphic, you can always click your mouse on the four boxes in the center of the layer and drag the layer anywhere you’d like.
Once you’re ready to apply the transformation, click the “Scale” button in the Scale tool dialogue (red arrow in the image above).
Step 3: Use Color to Alpha Filter
Now that my graphic is in place, I’ll lower the layer it is on so that it is now located below the wall image layer. I can do this my clicking on the graphic layer to make it active (red arrow in the image above), then clicking the “lower this layer one step” icon in the layers panel (green arrow).
Next, make sure your image layer has an alpha channel. To do this, right click on the image layer (red arrow in the image above) and click “Add Alpha Channel” (green arrow). If this option is grayed out, it means your image already has an alpha channel – you won’t have to add it in that case.
While your image layer is still active, alt+click with your mouse on the graphic layer (green arrow in the above image). This will create a selection in the shape of your graphic (you will see the moving dotted lines appear over your image – known as marching ants – denoted by the red arrow).
With the image layer STILL your active layer (green arrow in the image above), go to Colors>Color to Alpha (red arrow).
By default, the color (red arrow in the image above) will be set to white. This makes all colors in the image layer that contain white either fully transparent (for pure white) or partially transparent (depending on how much white is in a pixel). In order to make our graphic blend with the wall, including its textures, better, we’ll need to change the color. I can do this by clicking on the Color Picker icon (green arow).
I’ll then click and drag my mouse across the wall portion of my image (blue arrow) until I get a color I like (I went with a sort of middle-gray color from the wall – not too light, not too dark).
Next, I can adjust the “Transparency Threshold” slider (red arrow in the image above) to make the graphic less transparent (so that it is easier to see). This works by making the pixels that are currently totally transparent (i.e. have an alpha value of 0) slightly less transparent (by increasing the alpha value to whatever we set this slider value to).
On the other hand, if I want to make the pixels that are totally opaque slightly less opaque, I can drag the “Opacity Threshold” slider (red arrow in the image above) to the left to decrease its value. The more I decrease the value, the less opaque the graphic will be.
Finding a good balance between these two sliders will help the graphic blend well with the wall and look more realistic. Once I am happy with my settings, I’ll click “OK” to apply the changes.
I’ll click ctrl+shift+a to deselect my selection area.
That’s it! We now have a graphic that appears to be painted on a wall. If you liked this tutorial, you can check out my other GIMP Help Articles, GIMP Video Tutorials, or GIMP Premium Classes and Courses.