Thursday, 18 March 2010
I had a request, the other day, for an easy-to-follow tutorial on using layers in GIMP as most tutorials on the web tend to be specific to a purpose and can be a little confusing.
So, the aim of this Guide is to give a basic overview of layers in a non-specific way. This part covers what layers actually do and the window that’s used to control them. Part two contains a basic overview of creating and manipulating layered images.
Theory Of Layers
Before we can work with layers effectively in GIMP (Or Photoshop, for that matter) we need to understand what they are.
I tend to think of Layers as transparent acetate sheets, like those used on the old style overhead projectors, that can be placed over the top of each other to provide different effects. By ‘colouring in’ different parts of an acetate sheet, we can hide, change or obscure the layer(s) underneath it.
Indeed, I had teachers when I was at school (especially in science) who would use the principle to label, say, the parts of a heart after us students had all tried to name the ventricles, aortas and other bits and pieces. The principle in GIMP is exactly the same.
However, because we are using digital ‘sheets’, we can do much more with them and produce many more varied effects. Things like selective colouring (where we cut out sections of our top ‘sheet’ to make parts of the ‘sheet’ underneath visible) to applying textures (where our top ‘sheet’ is half see though so that we can partially see the ‘sheet’ underneath).
Of course, there are times when we might use multiple sheets (selective colour with a texture applied and some motion blur, perhaps) and this can, in the end, become quite complex, especially if layers are a somewhat unfamiliar concept.
The Layer Window
Here is our Layers window. Practically everything that we might want to do to a layer, as a whole, can be done in here and it’s the key to working with them.
Going from the top we have:
Mode – This makes it possible to change an entire layer to do a great variety of things. One of the common ones that you may come across is the Overlay mode. This is used with textures quite a lot.
Opacity – Makes your layer more see through, or less. (0% is completely transparent, 100% is completely solid)
Lock – Locks the layer so that it can’t be moved or changed.
Under those settings is the layers window itself, that holds all of the layers in your image.
The eye symbol makes the layer visible or invisible, essentially allowing you to turn the layer ‘on or off’. Then you have a small ‘preview’ of that layer and then there is the layer label. The one visible above is called ‘background’. The GIMP default for the first or ‘base’ layer. It’s a good idea to rename layers as you work, so that you know what each of them does.
At the bottom of that window, there are some small icons. From left to right:
New Layer – Creates a layer at the top of your pile
Move Layer Up – Uhuh, no prizes for that one
Move Layer Down – Or that one
Duplicate Layer – Will make an exact copy of the selected layer and put it on top of the pile. I use this in Selective Colouring. I duplicate the original image layer and then convert it to B&W, before cutting holes in it with a paintbrush.
Anchor Layer – If you copy and image and paste it into an image you’re working on (such as applying a texture on top of an image), it will initially appear as a floating layer. By clicking the anchor, it will ‘stick’ it to the layer directly underneath it
Delete Layer – Don’t like it? Bin it! :-)) This will delete the selected layer.
Note: All of these tasks (and many more) can be carried out by right clicking on a layer
Part 2 of this guide will include information on basic manipulation of layers within GIMP
