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Use Gimp to improve shots taken in foggy conditions - Although fog can serve a purpose in photography, there are also times when it detracts from the quality of the image instead of enhancing it. Michael bates looks at a way to clean up your digital fog shots using Gimp.
Here, even though the fog acts as a nice device for removing the background so our attention is forced towards the windmill it also makes the windmill less focussed and harder to distinguish. What we want to do is make the foreground more detailed and distinct, and improve the exposure of the image as well as removing the branch that is encroaching from the right of the image.
Step 1 As always, begin by duplicating the Background layer and renaming the new layer ‘Edit’ or something, just so we can distinguish it from the original in the list of layers later on.
Step 2 First, let’s correct the exposure so that there is a nice contrast between the highlights and shadows.
Open the Colours>Levels tool and you’ll see that there is a point where the histogram stops at the right; this is the area where the brightest colours are, so reposition the white arrow to this point so that the brightest areas of the image are now displayed as white.
You can also bring the black arrow towards the start of the histogram, but in this case the image becomes too dark if we bring it right to the start of the graph, so we’ll only increase it a few points.
Step 3 Now that our edited layer has a better contrast we can start cleaning the image up properly. Start by opening Filters>Enhance>Unsharp Mask, we are going to use this to make things such as the bush and the blades of the windmill contrast more sharply with the background so they are more easily defined, therefore keep the Threshold and Radius settings low so fine details won’t be lost.
Step 4 Despite the last two steps the contrast may still be a little too low for all the detail of the shot to be apparent. Therefore open the Colours>Brightness-Contrast tool and play with the contrast until your image looks better, but not over-dark. The Brightness may need one more tweak after you’ve altered the contrast, though this depends partially on personal taste.
Step 5 Now, there is a good chance that after all that messing around with the contrast, brightness and exposure of the image there will be some speckling of the colour. By this I mean there will probably be visible red, green and blue specks, especially in darker areas such as the base of the windmill.
To combat this we have to blur the colours back into each other, however this would normally mean losing the detail of our image.
Luckily Gimp contains a Selective Gaussian Blur tool in Filters>Blur that allows you to blur colours together that area similar, so the line between the edge of the windmill and the sky will stay crisp but the speckling will be reduced a bit. The higher you set the Max Delta setting the more the colours will be blurred, but this means you lose detail in things like the bush and the grass that are more or less a uniform colour, so make sure this setting is low before you apply it in images containing areas like grass unless you want them blurring too.
Step 6 Now to remove that branch that is creeping into the image from the right. All it currently does is distract people’s attention and clutter the image with a dark, depressing presence on the side of the image. So zoom in a good way, select the Clone Stamp tool (‘C’). Hold control and click somewhere in the sky near the branches, then starting at a similar latitude as your source start to cover the leaves.
Step 7 After doing that there will be an obvious patch of sky that you have placed in where the branch was, so select the Healing Brush (‘H’) and select a source as you did for the Clone Stamp. Then draw along the edges of the area you just replaced and it should blend in as a result. It may take several applications of this to effectively cover the area; it may be worthwhile zooming out to see how it looks every now and then.
Step 8 The last thing we are going to do is to try to remedy the washed-out appearance of the background foliage in the left of the image. Use the Lasso tool (‘F’) to select one side of the foliage, then hold shift whilst drawing around the foliage on the other side of the bush to add this to your selection. Press Control and ‘C’ to copy these parts of the image to your clipboard and then Control and ‘V’ to paste them. In the Layers pane there will be a new layer called ‘Floating Selection’; right click this and select ‘New Layer’. No immediate change will be evident, but don’t get too confused; the next step will change all that.
Step 9 In your new layer go to the Layer Options drop-down menu and select ‘Overlay’. The original selection will be obvious, but the foliage will look better defined, so all we have to do now is to make the selection less obvious. Right-Click the new layer in the Layers pane and select ‘Add Layer Mask’, then use a soft-edged paintbrush to colour the bits of sky etc. that give away your edit to this area black.
Pay special attention to the edges of the selection near the bush where you can see through, using the blurred edge of the brush to create a gradual shift between the two layers.
Finally reduce the opacity of the layer to make the effect less extreme and your image should be looking much mroe defined and brighter than before.