EDIT PHOTOS WITH GIMP
Turn grey skies blue
An overcast sky can ruin an otherwise striking photo. The good news is that gloomy images are easily brightened up. Open your photo, then find another image that features a blue sky. Copy this blue-sky image (press R for the select tool, Ctrl+a to select all, then Ctrl+c to copy). Now return to your first image, create a new layer (Ctrl+shift+n), then paste the blue-sky image (Ctrl+v). Press Ctrl+h to finalise the paste.
Hide this new layer by clicking the eye beside its icon in the Layers panel, then click the layer with your original photo. Press U to switch to the Fuzzy Selection tool and click the overcast sky. If this doesn’t select all of it, hold down the Shift key while clicking other areas of the sky to add them (this tool works best if the sky is a uniform colour).
When you’ve selected the entire sky, reveal your pasted layer again by clicking the space next to its icon where the eye used to be (the eye will reappear), then select that layer by clicking its name in the Layers panel. Click the ‘Add a Mask’ button at the bottom of the Layers panel (second from the right), select ‘Black (full transparency)’ then click Add. Your pasted layer will disappear but the selected area will stay selected.
Press P to select the paintbrush tool, then select white as the active colour. Now use your cursor to paint within the selected area on your image. As you do this, the brush will wipe out the mask that you applied in that area, revealing the blue sky of your pasted image, which then appears to be part of the original.
Change an object’s colour
Sometimes you’ll have a photo with a single object whose colour doesn’t look quite right, or you want to change its colour for dramatic effect.
Open the image you want to edit, then click Colors, followed by Map, then Rotate Colors. This brings up three round colour palettes, of which you’ll use the top two. Click the From bar in the Source Range section (see screenshot left), then drag left and right to move the first clock hand on the palette to the right until it sits at one extremity of the colour range you want to use. Because we want to change the colour of the red bands on a lighthouse, we’ve positioned it at the start
of the reds.
Now click in the To area (below From) and again drag until the other hand on the palette points to the other end of the range of colours. In our example, we’re including all red tones (see screenshot bottom of page 52).
Next, in the Destination Range section below, drag within the From and To sections to move the hands on this palette so they cover roughly the same area of colours you selected in the Source Range section. Crucially, however, don’t select the same colours. Instead, select the ones you want to replace the original colours with. In our example, we’ve selected an equivalent area of green tones. GIMP translates the old colours into the new ones as you adjust the palettes, so you can check the result as you go.
Uncover hidden details using curves
We’ve already explained how Paint.net can help fix poorly exposed images. Here, we’re going to use GIMP’S Curves tool for even more nuanced control. In our example photo below, the bright sun on the Roman temple caused our camera to reduce the exposure. As a result, it’s blotted out all the detail from the cafe in the foreground. Brightening the whole image would overexpose the temple and you’d lose detail there, so instead open the Colors menu and select ‘Curves…’.
Dragging the diagonal line up and down in the lower-left quadrant makes the shadows lighter and darker; doing the same in the upper-right quadrant has the same effect on the highlights. When fixing a photo like our example, we want to drag the lower part of the curve up to lighten the shadows.
To prevent our changes affecting the mid-tones and highlights in our image, we need to first click the middle of the line to fix that point in place. By doing so, any changes we now make to the curve below this point won’t affect the section of the curve above it. We don’t want to brighten the shadows too much as the contrast draws the eye to the temple. However, a minor adjustment, as we’ve made here, reveals a group of tables and chairs, adding interest to the foreground.
Give mono images more impact
Removing the colour from an otherwise ordinary picture is a great way to give it an interesting look, but simply using a black-and-white conversion tool doesn’t give you much control. For better results, open your photo in GIMP, click the Colors menu and choose Mono Mixer in the Desaturate sub-menu. This presents you with sliders that let you adjust the intensity of the grey tones derived from the reds, greens and blues in your original image (see screenshot above). So, if you want to boost the sky to make the most of some dramatic cloud formations, adjust the blue slider. To lighten the grass below to stop it dominating the photo, focus on the green slider. You can adjust any of these as much as you want, with GIMP previewing the results as you go.
Remove blemishes and dust
Dust on the lens, blemishes on someone’s face or, as in our image below, dirt on a window are easily removed using GIMP. Rather than trying to match the surrounding colour and painting over them, switch to the Clone Stamp tool by pressing C. Now hold down the Ctrl key while clicking on an area within the image that’s similar to the one you want to cover up (in our example, we’ve clicked on the sky). Now release the Ctrl key and use the left mouse button to paint over the blemish. GIMP will sample the area you clicked while holding Ctrl and use it to hide the imperfections in your picture.