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Using Gimp - Partie 4
This month, we will discuss probably the most powerful feature of GIMP: Layers. If you can grasp the concept of layers and work them to your advantage, you can create anything. First, let's make sure we have our layers window showing and ready to use. If you don't have the layers tab available to you, click File > Dialogs > Layers in the main menu. Here's how layers work: think of each layer as a transparent sheet of plastic. The idea is that you draw all your different things on separate sheets of plastic then stack the plastic sheets in a particular order to achieve your result. Similar to how an animator works. The background is on one sheet, the character on another sheet and any foreground details on a third sheet. Stack them properly and you will have the character with the foreground on top of it. Same with GIMP layers. If you open an image in GIMP, and display the Layers tab (or window), you will see that your image is displayed as a single layer with the name 'Background'. Below the list of layers, you will see several icons. Think of these as shortcuts to menu options. From left to right they are: Create New Layer, Raise Layer, Lower Layer, Duplicate Layer, Anchor Layer and Delete Layer. Those are pretty self explanatory. Using the selection tools from last month's article, I'm going to use the circle tool to select the planet. And from the menu choose Edit > Copy, then Edit > Paste You can see that I now have a new layer (named 'Floating Selection'), but it needs to become permanent, so click the New Layer icon. It now has a preview icon, and is automatically renamed to 'Pasted Layer'. If you want to rename a layer, just double click on its name, and enter a new name, followed by the Enter key. If I hide the original 'Background' image, you can see that the selected, copied and pasted planet is now on its own, completely separate, layer. Our first new layer! TIP: You can copy from one image and paste in to another image. Don't worry about the two-tone, chess-board pattern in the background. It's just there to signify complete transparency. So now, with the planet selected, I'll click the Duplicate Layer icon to give me a second planet. To move the layers, you use the Move tool, select the layer you want to move, then click and drag it into place. I'll use some of our color altering techniques to change the color of one planet to make it easier for you to differentiate between the two planets. TIP: If you have two images open, you can drag and drop layers between them! Let's create a new blank layer. A new layer is created above the layer you are currently on, so I'm going to select my (hidden) Background layer and then click the New Layer icon. Up pops the New Layer window (above). From top to bottom: We give the layer a name (preferably something descriptive! I'll call mine 'Space'); Width and height we won't bother with just now, as we want the layer to be the full size of the image; Layer Fill Type we will leave as transparent. You can choose white, or one of your foreground or background colors if you wish. Now, I'll make my foreground color black and fill my 'Space' layer with black color. So now I have two planets out in space. I don't need the original image any more, so I select that layer and click the Delete Layer icon. So what if I wanted the orange planet in front of the blue planet? I click the orange planet layer, then click the Raise Layer icon. Think of your layers as going from bottom to top. So first, GIMP lays down the 'Space' layer, on top of that it puts the blue planet layer, and, finally, on top of that the orange planet layer. When saving, you want to make sure you save your image in the GIMP format (XCF). The next time you load the image you will still have all the layers intact for manipulation. Saving as JPG or PNG will flatten the image and you will lose your layer information, so always keep an XCF version! To save, you click File > Save As from the menu, and make absolutely sure the filename ends in .xcf (right). Many effects can be applied to layers to make them even more powerful. Try moving the Opacity slider (above the list of layers). Each layer can have one 'mode' applied to it. These are listed in the drop-down menu above the Opacity slider. Have a play with these effects. You can get some nice looking accidents with these modes. Above is the basics of layers. No doubt, we'll talk more about them in future articles, but, for now, have a play with copying and pasting, raising and lowering layers, and moving them to create a pleasant composition. Next month, we'll delve in to measurements (and measurement types), rulers and cropping images.