The Designmark Graphics blog
Quality tutorials for Inkscape and GIMP
This tutorial will take you through the steps I use for drawing bright streaks of light against a dark background in GIMP. We'll start off with the Path Tool to set up our streak, then apply some effects and different layer blend modes to get that powerful, bright outcome you can see in the final image below:
Skills you'll be developing in this tutorial
- Managing layer blend modes to create a bold light effect (Screen, Dodge, Overlay)
- Taking control of brush settings to make scattering quick and easy
- Using gradients to amplify your images' impact and create greater contrast
Step 1 - Set up the document and create your background
Create a new GIMP document at a size of your choosing by going to File --> New or by pressing Ctrl and N. I'm going to go big and make a new image that's 1280 pixels wide and 1024 pixels tall. Choose any background colour - we're going to change that shortly anyway.
Step 2 - Create background clouds for the image
As I said, we're going to alter that background colour slightly. We do want to use black, but a straight black of #000000 isn't quite going to achieve what we need, so let's go with a black of #0a0a0a and fill our base layer with that instead. Use the bucket tool (Shift and B) or Ctrl and , to quickly fill a layer or selection with the currently active foreground colour.
Then, make a new layer above the first using Ctrl, Shift and N on the keyboard, or Layer --> New Layer in the menus. Accept the settings that appear and, using the free select tool (F on the keyboard), draw out a nice large selection in the centre of your piece that starts and finishes at the same point.
Go to Select --> Feather and use a big radius: say about 320 pixels or so. Then go back to the menus and select Filter --> Render --> Clouds --> Solid Noise and use the settings below to get some nice, diffuse black and white clouds to work with.
Adjust this layer's opacity using the slider, and set it to about 20%, so that it's visible over the black background, but only just.
Then create another layer above this one, and fill it with a deep purple colour - I've used #7c1169 from GIMP's palette - and change this layer's mode to Overlay in the panel. At this point you should have some pleasingly-coloured dark clouds as a backdrop for your piece.
Step 3 - Make the beams
Make another layer at the top of your image, above the cloud layer we've just created. Then get your path tool (B on the keyboard) and use it to draw a big zig-zag, S-shape or curve in the middle of your document. You'll get a feel for what works and what doesn't, but my tip is to keep your paths to as few stop points as possible to get a smoother curve, and make them a bit longer than you think you'll need. The streak I've made here is just three points: I've held down the mouse button down and dragged it quite far to get a good long swish at each point. You can see this by the long handles either side of the anchor point.
From the palette, make your foreground colour white, and switch to your paintbrush tool (P on the keyboard). From the Brushes panel, select a fuzzy circle brush (one with a Hardness of 75%, say) with a radius of about 9 pixels. You can go bigger if you want to but this gives quite a nice effect to start with. Select Basic Dynamics from the drop-down list below. Then go the Edit menu and select Stroke Path. Choose Stroke with a paint tool, choose Paintbrush from the drop-down box, and tick Emulate brush dynamics if it's not already set.
Hit the Stroke button and see your path painted on the canvas.
Now, make another layer above this one and repeat the stroke process, but with a larger brush than before (I've gone with 16 pixels) and setting the foreground colour to a really bold blue - in my case, #39e7e5. GIMP will use the same path as before and create a blue-brushed version on your new layer. After you've stroked this path, change this layer's blend mode to Screen.
Now we're getting somewhere. Repeat this last step on another new layer which sits below the other two streaks, leaving its layer mode as Normal. If your layer appears in the wrong order, just click and drag it into the correct position in the Layers panel (Ctrl and L). Using a Gaussian Blur (Filters --> Blur --> Gaussian Blur), blur this layer by an amount that's comparable the brush size you used last; so that's 16 pixels for me.
Step 4 - Give your beams some 'oomph'
Now we're going to pull a trick that will really beef up the brightness of that beam. It's a little subjective as to what looks right, so experiment as much as you want. Make another layer that's on top of all the others. Reset your fill colours to black and white, which you can do quickly in GIMP by pressing the D key on the keyboard. Then flip them around to make white your foreground colour, and black the background colour. Fill the layer with black, and change its layer mode to Dodge. Then select your gradient or blend tool (L on the keyboard). Set the Shape to Radial, and in the Gradient pop-out, select Foreground to transparent.
Click and drag on your canvas to create a few, short white-to-transparent blends which lie over the top of your beam. See how dramatically that changes your light beams?!
Here's the layer in Normal blend mode, so you can see what the radial gradients look like normally.
And here's what the layer looks like in Dodge mode.
The Dodge layer mode works on black-to-white contrast - black has no effect on the layers below, while white has the biggest effect. Your blurred beam layers underneath are also coming into play and amplifying that 'pulse' effect that you can see.
Step 5 - Add some more light effects to grab the eye
Brilliant, we're nearly there. Let's just add one more decorative effect to finish things off and give our piece some style. Add another layer to the top of our stack, then activate your Paintbrush tool again and choose the "Sparks" brush from GIMP's default brush set. Open up the Brush Dynamics options in the Toolbox, tick the boxes you see in the screenshot below, as well as the Apply Jitter option, with an Amount of 3 or so on the slider.
Go back to Edit --> Stroke Path. GIMP will remember your path from earlier on, and paint lots of sparks along your streak of light, scattering them around because of the randomness we've introduced with our brush settings and jitter. Depending on how well this works first time, you might want to repeat this last step a couple of times to get more sparks, or adjust your settings slightly to make it work for your drawing's size.
Unless you've chosen a coincidentally-matching colour for your light swoosh, these sparks will probably clash with your existing colour choice, so we want to fix that. This is easy. Firstly, change this layer's blend mode to Dodge, as before. Then go to our menus at the top and choose Colour --> Desaturate, and choose one of the options in the dialog box that pops up. I usually go with Luminosity or Average, at this point. Keeping the Preview check box ticked will help guide you.
And there we go! You can repeat this last step on another layer, or maybe duplicate this last layer to intensify its effect, perhaps add a couple of blotches of light using a large, soft brush and the Overlay layer mode, and you should have a piece that looks pretty good.
Hope you've enjoyed this tutorial, we've covered several really useful techniques here, so well done! Did you get a good result? Did you enjoy this tutorial? Learn anything new? Share your thoughts in the comments section below.
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