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I create a lot of images. From book covers to annotated screenshots and everything in between. You might think I would default to using the likes of Photoshop -- but that's not the case. You see, I started doing graphic design way back when Photoshop was way beyond my price range. And even though I could now afford Adobe's de facto standard image editor, I still opt to use my favorite, open-source editor, GIMP.
GIMP stands for GNU Image Manipulation Project and it is the open-source equivalent of Photoshop. The biggest difference I've found between the two is that Photoshop goes out of its way to automate and simplify a lot of tasks. On the other hand, GIMP can do most of the things Photoshop can do, only some of those things have to be done manually.
So, yeah, GIMP isn't quite as user-friendly as Photoshop, but once you grow accustomed to how GIMP works, it's pretty fantastic.
One of the many features I regularly use in GIMP is Layers. The Layers feature is exactly what you think it is -- it allows you to add new layers to work with, which do not affect the layers underneath.
This comes in very handy.
Say, for instance, you have an image you want to customize. I'll explain by way of the cover I created for the third book in a new romance/crime thriller series I'm writing. The third book takes place during Christmas, so I wanted a very holiday-esque theme for the cover. I purchased a stock background image with a sack of gifts but needed to add a knife sticking out of the sack. I could simply paste the knife onto the background image but once I added that image, I wouldn't be able to manipulate it without affecting the base layer.
What if I wanted to change the angle of the knife? Or change its size? Had I added the knife to the base layer, that wouldn't be possible.
Instead, what I do is add a new layer to the image and then paste the knife into the new layer.
Let me show you how easy that is to do.
How to use Layers in GIMP
What you'll need: You'll need GIMP, which can be installed on Linux, MacOS, or Windows. The application is free and performs the same, regardless of which operating system you use. You'll also need an image to use as the base layer. That's it. Let's get to the layers.
1. Open your base image
Open GIMP from your desktop menu and then open the image you'll use as the base. When you open an image in GIMP it automatically assigns that image to the base layer and names that layer according to the file name.
2. Create a new layer
At the bottom right of the GIMP window, you'll see a toolbar. The far left icon (which looks like a rectangle with a + in the top left corner) is the New Layer button. Click that to open the New Layer window.
3. Customize your new layer
When the New Layer window opens, the first thing you'll want to do is name it. I would recommend naming the new layer based on the object it will hold. For example, I'll name this layer "Knife," so the layer is easier to find. Many of the images I create contain numerous layers, so it's easier to navigate them if I name the layers accordingly. I would also recommend leaving the rest of the options alone. Click OK and your new layer is added.
The next thing you'll do is open the object to be added. Once you have that object (image) open, you can simply copy it with the Ctrl-C keyboard combination. When you paste the new object, it will be surrounded by a dotted, blinking line. You can then resize the object, change the angle, and even erase part of it. For my image, I'll shrink the knife to 50% of its original size, angle it such that it looks like it's poking out of the sack, and then erase part of the tip, so it looks like it's sticking out of the bag.
One thing to keep in mind (especially if you want to shrink the new object) is that you want to manipulate the selected layer and not the whole image. That's crucial because if I were to, say, shrink the entire image, the knife would remain the same size (relative to the base image).
Another thing you'll need to know is that some actions (such as shrinking and rotating) can (and should) be done before you anchor the layer. Other actions (such as erasing) have to be done after you anchor a layer. To anchor a layer, make sure you have it just the right size and angle, and then click the anchor button in the layer toolbar (which is the third icon from the right and looks like an anchor).
Once you've finished working with the current layer, you can then add more layers to keep building on your work.
Layers are a very important feature of GIMP and will save you a lot of precious time and effort. By using layers you protect the base image from getting altered, while still getting the look and effect you want. Do remember, however, that if you want to manipulate a particular layer, you must first select it in the Layer pane before making any changes.