Vignettes are great, yes they can be regarded as a lens defect, but sometimes they can add that certain something to an image. I have seen other tutorials on the web which are very similar to this one, differing only in that I like to use Layer Modes for most of my vignettes. I particularly like the boost to contrast and saturation that the Multiply mode gives, I think it has a more retro feel. Anyway let’s begin.
Step 1. Open your image in GIMP, right click on the “Background” layer and select Duplicate Layer. Note that this new layer has become the active layer, as denoted by the white border.
Step 2. Right click on the new layer “Background copy” and select Edit Layer Attributes, enter the new name “Vignette” and select OK.
Step 3. Right click on the “Vignette” layer and select Add Layer Mask…
Step 4. In the Layer Mask dialog box choose the default White (full opacity) and select Add.
Step 5. Select the Blend tool from the Toolbox, or by selecting Tools > Paint Tools > Blend. Ensure that your Foreground color is Black and your Background color is White. Use the default FG to BG (RGB) Gradient and change the Shape: to Radial.
Step 6. Turn OFF the visibility on the “Background” layer by clicking on the little eye icon. Then Click in the center of your image (or the main point of interest) and drag out toward the corner of your image. Sometimes you may need to go out beyond the edges of your photo as I did in this example. Repeat this step as many times as is necessary, the aim here was to make the majority of Mischa’s face transparent.
This is a great example of Layer Masks in action. White areas are treated as Opaque (solid) while Black areas of the mask are treated as Transparent. The information is still there in the layer but the mask controls what is displayed.
Step 7. The Blend tool produces a very soft transition between black and white, we can sharpen the vignette by shortening this transition. Launch the Curves tool by selecting Colors > Curves… Click to add a control point in the center of the graph and then raise the right hand portion and lower the left hand portion. You may need to experiment a little here to see what works.
Step 8. Turn ON the visibility of the “Background” layer by clicking the little eye icon and change the Layer Mode: to Multiply
That’s it. one nice subtle vignette effect. I recommend that you experiment with some of the other Modes, Overlay can work well, Burn can give massive saturation boost and Subtract can give a very dark vignette. Also experiment with the opacity to lessen the effect.
If you are still not quite getting the vignette you want try changing the Mode back to Normal and use the Brightness/Contrast, Levels or Curves tools to manually darken the “Vignette” layer. If you are trying this make sure that you select the “Vignette” layer (as in the actual image) rather than the Layer Mask, the white border will tell you which is active.