Here you will learn how to use layers in Gimp, and we’ll have a look at the different options in the layer dialog.
This is aimed at complete beginners.
Let’s say you had a pencil and paper on your desk. On the paper you wrote “hello”.
Then you put another paper on top of that paper, but this paper is transparent paper.
On the transparent paper you write “world”.
Now it says “Hello world” when you look at the papers.
If you decide you don’t want to have “world” there you can simply remove the transparent paper. Or if you want to move the word “world” you could just move the transparent paper. You wouldn’t have to use an eraser at all!
In Gimp, you can think of layers as a bunch of papers stacked on top of each other, the bottom one is usually black or white, and all the others are usually transparent.
When I open up Gimp, and choose to create a new image, it looks like this:
The red arrow in the image is pointing at the layer dialog. If you can’t find the layer dialog on your Gimp, then in Gimp’s main window, go to Windows → Layers, Channels, Paths, Undo etc.
That should bring up your layer dialog.
The bottom layer in the layer dialog is called Background, you can think of this as a piece of white paper (although we can make it any color we want).
If you click on the add new layer button (see image below), a dialogue will pop up, asking you to name the layer, and chose whether you want the layer to be transparent, black or white. You usually want the layer to be transparent.
In the image below I created a transparent layer named “test layer”. I also painted some green on that layer.
The layers position in the layer stack is important to how the image would look. Let’s say we have three layers, a white background layer, a transparent layer with a green blob on it, and a transparent layer with a blue blob on it.
Example one, blue layer on top:
Example two, green layer on top:
Example three, background layer in the middle:
Let’s have a closer look at the options in the layer dialog:
1 – Adding a new layer. Clicking this will open up a dialogue that asks you to name the layer and choose whether it should be transparent, white or black.
2 – Move the layer up. Simply moves the layer up, in this case the layer is already at the top of the stack, so it can’t be moved further up.
3 – Move layer down. Pushing this will move the layer down, in this case the layer would be placed underneath the background layer, and we would no longer see the green stuff I painted, because the white background layer would cover it.
4 – Duplicate the layer. Pushing this button will simply duplicate the layer.
5 – Anchor the layer. This one is a bit special, and you usually only need it when you copy and paste. Let’s say you were copying something from one image to another image, when you paste, Gimp will create a layer named “floating layer” or “floating section”, this layer contains what you copied. Pushing the anchor will make this floating layer disappear, and transfer the contents of the floating layer to the layer you were working on before you pasted.
6 – Delete the layer. Pushing this will delete the currently selected layer.
Also notice the “eye” button next to each layer, pushing this button will toggle if the layer is visible or not.
If you look some more at the layer dialog you will notice three more settings:
Lock – Clicking this checkbox will lock the transparent pixels in the layer. What does that mean? Well, it means that you can only edit those areas on that layer which are not transparent. In the case of my “test layer”, I can only edit the green area of the layer, nothing else.
Opacity – This setting controls how opaque the things you have drawn on that layer should be. In other words, this controls how see-through the stuff you draw on a layer should be.
If I had three layers, the bottom one was white, the second had a green blob on it, and the third one had a blue blob on it. If I set the “blue blob” layer to 50% opacity, it would look like this:
The third setting you can adjust is Mode. Note that this is usually referred to as Layer mode.
Layer modes are basically certain settings you can apply to a layer, usually to achieve an effect you want.
Example, here is an image with three layers, a white background layer, a transparent layer with a green blob on it, and a transparent layer with a blue blob on it. If I set the blue blob layer to layer mode: Multiply, we get this result:
Explaining all the layer modes is unfortunately very technical, lots of mathematical operations and such, and therefore out of scope for this tutorial.
It is also much more advisable to experiment with the different layer modes to see what they do, not to mention way more fun!