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31 May 2013

How to Create a Textured Background Using GIMP Filters

What's Behind It All


What do you do if you have a nice photo of a person, animal, or other image, but the background is ugly or distracting, or you're really interested only in the main subject? Well, the first thing you can do is remove the background. (See Which Tool Should I Use to Cut Out an Irregular Image?) But then what? Now you have an image just hanging in space.

King Vulture Cutout Image
I feel like something is missing.

This novice-level tutorial explains one technique you can use to create a textured background for your image by using various GIMP filters and overlaid layers.


Step 1 — Create a Black Background


Open GIMP, set the Foreground color to black, then choose File > New and create a new image of an appropriate size. My image is 8.5 x 11 inches at 200 ppi. This will create a black layer named Background.

Create a Black Background


Step 2 — Create a Cloud Layer


To add some variability as a base for the texture, the next step is to add a cloud layer. Duplicate the background layer [1], then choose Filters > Render > Clouds > Difference Clouds [2] and play with the controls to create a cloud pattern that will look nice behind your image. (Make sure the Preview box is ticked so you can see what the filter will generate.) You can enter an integer in the Random seed box, or use the up and down arrows, New Seed button, or Randomize check box to change the seed. Ticking the Turbulent box creates amorphous blobs as opposed to mist. The Tilable option creates a rectangle of clouds that can be copied and tiled with itself. Detail is a value from 1 (fuzzy) through 15 (detailed) that adjusts the fuzziness of the clouds. X size adjusts how stretched or compressed the clouds are in the X dimension. Y size does the same in the Y dimension.

Render Clouds Dialog


Once you have a cloud pattern you're happy with, click OK, rename the new layer to clouds [3], and turn the layer opacity down to somewhere between 30 and 50 percent [4].

Low-Opacity Clouds


Step 3 — Create a Spotlight Layer


The next step is to create a highlight that will show around the cutout image that will be on top of this textured background. This will set the image off as if there's a spotlight shining on it. Create a new transparent layer [5] at the top of the Layers list. Using the Ellipse Select tool [6], drag out a fair-sized oval and use the Bucket Fill tool [7] to fill the oval with white.

Creating a White Ellipse


Then choose Layer > Transform > Arbitrary Rotation [8] and rotate the oval in a direction consistent with the lighting of your image.

Rotating an Ellipse


This will create a Floating Selection (Transformation) layer [9]. Right-click on it and choose Anchor Layer [10].

Anchoring a Layer


Choose Filters > Blur > Gaussian Blur [11] and enter a very high number [12]. I entered 1000.

Blurring an Ellipse


Rename the layer to spotlight [13] and lower the opacity to somewhere between 50 and 70 percent [14].

A Semi-Transparent Blurred White Ellipse


Step 4 — Create a Texture Layer


It's time to to add some noise or graininess. Create a new layer at the top of the Layers list and fill it with white.

The fun part now is experimenting with the Artistic filters. I chose Filters > Artistic > GIMPressionist [15]. The Preset <Factory defaults> will generate some directional noise. The angle can be adjusted in the Orientation tab with the Angle span setting. Pressing the Update button will show a preview of what the filter will generate.

To try another Preset, click on a name on the Presets tab [16], then click the Apply button [17], then the Update button [18]. When you're happy with the preview, click OK [19] to run the filter, which will change the white layer. If you don't like the result, use CTRL+Z, then choose other settings or another filter. If you just want some random noise, choose one of the noise filters from the Filters > Noise menu.

GIMPressionist Filters


Once you've settled on a filter effect that you like, rename the layer to filter [20] and adjust the layer opacity [21] so that it adds a nice level of texturing to the background. Here's the result of my choice of Crosshatch.

Crosshatch Filter Texture


Step 5 — Save a Reference File


At this point you should have a file containing four layers: a black background layer, a clouds layer, a spotlight layer, and a filter layer. Save this file as a reference. If you should ever need to create another background, you can copy this file and change any or all of the clouds, spotlight, and filter layers independently.

Step 6 — Colorize the Textured Background


The final step is to add some color to the textured background (assuming you want something other than a grayscale version). First, you need to combine all the layers into one layer that can be colorized. The easiest way to do this is to right-click in the Layers list and choose New from Visible [22]. This will create a layer named Visible [23].

New From Visible


Next, add your cutout image as the top layer by dragging the image file from the file explorer onto the textured image. Then, with the Visible layer active, choose Colors > Colorize [24] and slide the Hue slider [25] back and forth until you find a color that goes with your image. Press OK [26] to save the color.

Colorize an Image


[NOTE – 02 Oct 2013: A better way to color the background is to add a new layer of a solid color above all the texture layers and set its layer Mode to Color. Then use Colors > Hue-Saturation to adjust the color as necessary. This method is much more flexible.]

When you're satisfied with the look of your complete image, export it with File > Export to a raster (.jpg, .png, etc.) file.

King Vulture on Textured Background
Did I pass my background check?


UPDATE – 13 March 2014

I have recently switched to using the fog filter (Filters > Render > Clouds > Fog) most of the time. I set the Fog color to a light to medium gray and the Turbulence to somewhere between 0.8 and 1.2. Every time the filter executes it generates different output. Sometimes I have to run it only once to get a look I like. Other times I run it several times until I see something I like. I place the fog layer over a black layer and adjust the opacity of the fog layer to something that looks good. Then I create a complementary color layer over the fog layer and change the layer mode to Color. Occasionally I'll import a photo of a texture (like stucco, for example), desaturate it, and place it between the fog layer and the color layer with an opacity that looks good. This technique of creating a background tends to look really nice behind photos of animals. For an example, see my processed photo called Bird on a Catwalk.


Related GIMP Tutorials

How to Create a Textured Background Using Color Functions and Bump Maps

See Also

Creating the “Fibonacci Cockatoo” Portrait
Creating the “Grumpy Gorilla” Portrait

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