Blend two exposures to make one good one using Gimp

A shot like this is always hard to get quite right, if you set your exposure so that the shadowy trees are clear then the light will blow out your exposure, and if you want a clear and controller exposure of the opening at the end of the road, you will get dark trees.

Here we have a predicament; we have two exposures of an image; the one on the left is too dark for the peripheral detail to be of any use at all, and the image on the right has an overexposed centre.

We would probably find little use for the underexposed image without editing it extensively, but we can make it useful by taking the centre of the image and replacing the overexposed area in the other image. This will give us a third version of the image; one where the light at the end of the tunnel is not blown out, yet with the trees still detailed and vibrant.

Step 1 Open both your images in Gimp, and go to the underexposed image. Select the Lasso tool (‘F’) and draw a selection around the area that is roughly equivalent to the overexposed area on the brighter image. Press Control and ‘C’ to copy this area.

Step 2 Go to the overexposed image and press Control and ‘V’ to paste the darker image into the other image. Right Click the ‘Floating Layer’ in the Layers pane and select ‘New Layer’ to place the pasted area into its own layer. Use the Move tool (‘M’) to place the dark are into roughly the right area.

Step 3 Set the Layer Mode to ‘Multiply’ and reduce the opacity to around 20-40% so that the grafted image will look a bit more like the lighter image. If it looks like some items are duplicated then your image my need some Transforming to properly overlay the image; here I needed to rotate my image a few degrees using the Rotate tool (‘R’), but if both shots were taken with a tripod then there shouldn’t be many adjustments required.

Step 4 Now, it’s still obvious where the layer is overlapping the original. To undo this, right-click the grafted layer in the Layers Pane and select ‘Add Layer Pane’. Take the Paintbrush tool (‘P’) and select a soft-edged brush and put black as your foreground colour. Paint around the edges of the image so that they will be softened.

Step 5 Now there are just a couple of touch-ups required. First is to paint the road transparent in the Layer Mask, so paint over that with the black Paintbrush as before. The grass verges at the side of the road will look too dark as well now, so paint over these with black, and then some of the canopy will be too dark and contrast starkly with the other foliage so paint over any such areas too.

Your image is now ready to flatten and export looking better than either of the original exposures.