Create a grungy flag design in GIMP

Involved GIMP Tutorial


If there's one thing that you need to experiment with in GIMP, it's using images as textures and overlays in your work. It can take a flat image and really give it some interest and detail and, using the many different blend modes available in GIMP, there's lots of ways to do it, too.

In this tutorial we'll take a collection of free images obtained from the web and a set of downloadable brushes, and use GIMP to create a really powerful grungy image of a paint-splattered flag.

I won't go into how to obtain and install brushes for GIMP in this article; if readers request a tutorial for that then I'll certainly write one, but let's just focus on how they're used here. If you're totally stuck, there's a link to an existing guide over on one of the GIMP forums in the Resources list below.

Here's a preview of what we'll be making today. Feel free to substitute your own country's flag in place of my Union Jack - the technique is still the same.

A grungy Union Jack flag designed in GIMP

Skills you'll be developing in this tutorial


Download the following resources using the links below. All files are nice, large images and should give plenty of coverage of the screen as well as flexibility if you need to scale your creation up/down.

Step 1 - Set up the canvas and import the flag image

Open up GIMP and create a new document with Ctrl and N or File --> New. In the options boxes, set the width and height of this new document to be 2000 and 1400 pixels respectively. Choose any colour for the background fill as we'll be substituting it later anyway.

Set up the canvas for the image

Open up the flag image which you downloaded. The Union Jack is an SVG (Scalable Vector Graphic) image, which is a vector file format GIMP is more than comfortable opening. File --> Open As Layers or Ctrl, Alt and O will bring up the dialog box. Navigate to your file, select it and click open. You'll see the import box appear. You can tinker with the settings to scale the vector image as you're opening it, but whatever GIMP assigns by default is fine for us here. Click OK when you're ready.

Open the flag image as a new layer

Create a new layer above this one, onto which we'll add our paint splotches. Bring up the Layers panel with Ctrl and L, then add a new layer using the button or Ctrl, Shift and N. It will be added above the flag layer, which is just what we want.

Add a new layer for paint splotches

How we'll make this work is to pick colours from the flag layer to use in our paint strokes, then apply them to the new layer where we want them to go. That way we keep the original flag pixels intact and can easily re-jig our efforts on the top layer if we want to make changes; a form of non-destructive editing. Activate the Colour Picker tool with the O key, and tick the Sample Merged check box in the Tool Options panel. Click on a section of the flag to set the Foreground colour to match it.

Use the Sample Merged facility to select colours on layers below the current one

Click on a coloured area of your flag, which will then set your Foreground or Background colour to be the same as the pixel(s) click beneath the pointer.

Use the colour picker to set your foreground colour to match the one sampled underneath

Switch to the Paintbrush tool with the P key, and select one of the brushes from your splatter brush pack. Set the size to between 120 and 260 pixels in the slider box and click somewhere on the canvas which is the same colour. Overlap the brush with the edge to make it look like it's dripping or splashing into the region next to it.

Brushing over areas with the same colour makes it look like the colour is spilling over

Now repeat this process for a while using this colour and the others from your flag image. A useful tip is to hold Ctrl with the Paintbrush tool active, which will switch to the Colour Picker for as long as you've got Ctrl held down; a great time-saver.

Try out different brushes, experiment with their sizes and orientations using the Tool Options and generally focus on the areas where different colours join on your flag.

Continue brushing to make the colours look messy and runny

It's handy to remember that in general the drips should seem to be running 'out' of colour zones as though they were still set or melting. That will achieve the best-looking outcomes here. When done, your colours should almost look like they've been 'thrown' at the flag design, whilst keeping it recognisable as well. Great. Next, we'll texture our picture up to really start roughing up this flag.

Step 2 - Roughen the image using grungy textures

Open the first texture - the cracked wall image - as a new layer in your GIMP document (Ctrl, Alt and O). You can also drag in the file from a window outside of GIMP if you prefer that method. In the Layers panel, make sure it's the topmost layer (click and drag it up to the top if not) and set the Blend Mode of this layer to Grain Merge. Reduce the opacity slightly to 80%.

Add the first texture image and blend it into the flag

Looks good, but we've got some problems here too. There's way too much texture for our flag, meaning we need to cut out the shape and keep it to the areas we're interested in covering, only. But by default, GIMP imports JPGs with no transparency, meaning any areas we clear on this layer won't become see-though; they'll change to be the background colour instead.

So, let's add transparency to the layer: right-click the layer in the panel and select Add Alpha Channel. You'll see the way the layer is displayed change slightly (the text will become normal weight instead of bold).

Add transparency to the first texture layer

Now to the second problem. The texture is overlaying the background as well as our flag, and that's not what we want. Holding down the Alt key, click on the thumbnail image of the Union Jack flag layer. This will turn that area into a selection on your current layer. Then click Select --> Invert in the menus to swap the selection to all the region outside the flag rectangle. On the texture layer (click to activate it, if it isn't already), clear this region with the Delete key.

Discard the unwanted areas of the texture layer

Now open the grunge texture as a new layer and go through the same process, but this time using a Blend Mode of Multiply and an opacity of 75%. Don't forget to delete the unneeded outside area on this layer too; the right selection area may still be active if you haven't made any other changes yet.

NB. When you import it, GIMP brings up a prompt asking whether to convert the colour space of this image. It doesn't matter which option you go for as it's black and white only, but just for the record, I clicked Keep.

Import the second flag texture overlay

Blend the second flag texture overlay into the image

Things are starting to look really good; now for the finishing touches.

Step 3 - Adjust colour and lighting for a moodier result

Well done - now our flag is textured up and looking heavily stylised: just what we're after. At the moment it does still look a touch ordinary though, because of the even lighting over it. Let's change that situation. Add a new layer at the top of the stack as before, and set its Blend mode as Overlay. Then switch to your Gradient or Blend tool with the L key. Click on foreground and background palette squares and set them to a mid-yellow and orange respectively.

Set up the colours for a gradient

In the Blend Tool's options panel, select FG to BG in the Gradient option box, and a Radial gradient from the Shape options. Click and drag a long blend line from the centre of the canvas towards the edge of the flag region.

Create the yellow-orange gradient in the middle of your canvas

Reduce the opacity of the gradient layer to around 80% to reduce the effect so it's not too overpowering.

Lower the opacity of the gradient layer slightly

Select the original flag layer again and use Filters --> Light and Shadow --> Drop Shadow to being up the Drop Shadow dialog box. Set an X-Offset of 20 pixels, a Y-Offset of 20 pixels, a Blur Radius of 140 pixels a colour of black and an Opacity of 75 %. Leave the Allow resizing box ticked, so the resulting shadow can make a new border outside of the flag layer (otherwise you won't be able to see it). Click OK when you're ready.

Set up and add the flag's drop shadow

This drop shadow means we can achieve some separation between the main object in our image and the background. Ah yes, the background. We could do with one of those about now...

Step 4 - Organise layers into groups and create a background

We've got a few active layers on view here and could do with organising them better so we can add, and experiment with, backgrounds more easily. Fortunately, GIMP's excellent Layer Groups feature will allow us to do this quite easily.

Make a new Layer Group by clicking the folder icon in the Layers panel or using Layer --> New Layer Group in the menus. Then click and drag all your existing layers into the folder, stacking them in the same order as before.

Layer groups are a great way of managing layers which are related to each other only

Maintain the same top-to-bottom order of your layers as before. When you're done, your layer stack should looks something like this:

Keep your layers ordered as before

Click the eye icon next to the flag's layer group to hide it while we work on our background. That should leave your Background layer outside of the group and visible, and everything else inside it and hidden. Select this Background layer and open the brick wall texture image ...As New Layer. Position it roughly centrally so that you've got a good coverage and no half-brick levels at the top or bottom of your image.

Open the brick wall texture image as a new background layer

Now, this is a great image but it's clearly too busy to leave as it is - it will distract the viewer from the flag we've spent all that effort making look brilliant. So what we'll do next is to balance these elements out more evenly.

Begin by opening the Colors --> Hue-Saturation dialog box, and applying settings of Hue: 11, Lightness: -92, Saturation: -85 on the Master colour wheel to almost (but not quite) desaturate and darken the layer.

Adjust the lightness and colour of the layer using the Hue-Saturation settings

This should give you a darker brick texure layer which is almost greyscale.

Afterwards you'll have a near-greyscale result

Add another layer above this texture layer, and change its Blend Mode to Overlay, with an opacity of about 85%. Activate the Blend tool again. Set the foreground colour to a mid-brown, the background colour to a light orange and set the Gradient type to FG to BG as before. Draw a large Radial gradient from the centre of the image outwards.

Create a colour overlay for the brick texture

Lovely. Now to really set things off. Add another layer that will sit above this colour overlay and call it "Vignette". Grab the Ellipse Select Tool (keyboard shortcut E) and drag out a wide ellipse across the middle of the canvas. Press Ctrl and I (or click Select --> Invert) to swap the selection area to the region outside the ellipse.

Set up a selection area around the edge of the image canvas

This has enabled us to select the area around the edge of the image canvas; perfect for creating a dark vignette to focus attention on the central area. To do it successfully, we need to soften this selection a lot, so click Select --> Feather and enter a value of 800 pixels in the dialog box that appears, clicking OK when done.

Now set your foreground colour to black, and press Ctrl and , or click Edit --> Fill with FG Color to fill this now-very large selection with black. Over in the Layers panel, leave the Blend Mode as Normal, but reduce the opacity a little; to around 90%, say. Cancel the selection with Ctrl, Shift and A or Select --> None from the menus.

Feather the selection heavily to soften it

On another transparent new layer above this one, add some very large paint splats like we did with the flag, originally. This time you'll need big brushes - 600 pixels in size at least and anything up to 1,400 pixels - then dab the new layer with several spots in bright shades of yellow, green and pink. Change the Blend Mode to Overlay and give it an opacity of about 60 - 70%. You should end up with quite a nice, almost graffiti-style messy brick wall.

Add paint splat overlays to the wall texture

Make your flag's layer group visible again to see how things are looking. Add some more splats to your wall and adjust its overlay opacity if you think it needs tweaking. You might like to pop another at the very top of your flag group, and add a white-to-transparent radial gradient in **Overlay blend mode; this will give a strong highlight to the flag and boost its brightness compared to the wall background.

Consider adding a strong highlight at the top of the image

Finally, select the flag Layer Group and press Shift and R or click Layer --> Transform --> Arbitrary Rotation. Using either the mouse or by entering the number in the dialog box, rotate the flag group anticlockwise by about 12 degrees to give an off-centre result that's much more in-keeping with the messy feel of the piece. All layers in the group will be affected and you'll probably see GIMP take a second or two to apply the transform to each layer individually.

Rotate the flag group anticlockwise slightly

And there you have it: a punk-style, grungy flag and background created from downloaded assets and edited to perfection in GIMP. Well done!

The final flag with grunge effects

Using the same techniques and even textures, you can do an awful lot. This blog has many readers from Germany, so here's a grungy German flag for you guys.

A grungy German flag created in GIMP

And Spain, here's some love for you and your beautiful flag too!

A grungy Spanish flag created in GIMP

Have you enjoyed this messily textured tutorial, or has it just left you feeling a bit dirty? Let me know in the comments section below.

Mark is the Editor and owner of Designmark Graphics Ltd. Publishing tutorial articles and guides for Inkscape and the GIMP, this blog aims to boost the profile of these Open Source graphics applications and showcase what they are capable of.

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