2. The Multilayered Graphic File
Let's understand the concept first.
2.0. The Concept
Leave the computer away. Suppose you have a base map made of paper (on a page of a real atlas).
What do you do? Do you start drawing directly on it, ruining the atlas permanently?
Of course not! You take a semitransparent sheet of paper, put it over your base map and draw on it, while seeing the base map underneath, through the semitransparent sheet of paper.
See, these are layers (the base map on the atlas page is a layer and the semitransparent sheet is another layer).
If you want to further separate your elements, you could use more than one semitransparent sheet: one for the borders and coastlines, one for the labels, one for coloring, one for war maneuvres and so on.
It is important to have all these on different layers. What happens if you want to select an area (for colouring for example) and it contains some text on the same layer? It certainly gets in your way. With the labels on a different layer you are never bothered by them while always being able to see them!
2.1. The File
Real Image Editors (not Windows Paint though) organize their image file in layers stacked on top of each other. The transparent or semitransparent parts of the upper layers let you see through parts of the lower layers.
You can give these layers meaningful names, change their order (which one is on top or at the bottom, etc), set their relative opacity, toggle their visibility, merge or duplicate them.
All the work is done on the layered file which remains saved on your computer for future use.
For online usage you have to export it as a normal single layered graphic file like a PNG for plain maps (without the Google Earth overlay) or a JPEG for overlayed maps (containing the Google Earth overlay).
2.2. Using Paint.net
If you already have an Image Editor capable of using layers and you know how to use it (at least a little), you may skip this section and use your favourite Image Editor instead of Paint.net (my choice). Most of the concepts, commands and actions will be identical or similar.
If you decide to use
Paint.net, you have to download it from
here. It is completely free and safe, with no adware, spyware, etc.
The setup is simple and you will be ready to go in a few minutes.
The interface is quite simple and intuitive. If you have trouble using it, you may get help on their
forum. Or ask me. I am a computer geek and a little image processing geek as well.
If you have never used a decent Image Editor before, allow yourself several hours to get used with the software and the concepts it employs.
2.3. Creating your layered file.
I will use in my tutorial Paint.net as the Image Editor. If you use another Image Editor, the process may be a little different.
Open Paint.net. A new layered graphic file is automatically created and shown on the screen. It is filled with white uniformly and contains only one layer called
Background.
Do not worry about its size in pixels for now. If Paint.net displays inches or centimeters instead of pixels, you should select the measurement in pixels from the
Statusbar.
Save the file as Paint.net file (*.pdn) in the same folder where you saved your base map earlier. Give it a meaningful name.
Remember to save often (CTRL+S). Especially if your computer is old, slow or buggy.
Notice the
Layers window in the lower-left corner of the main window.
Click the
Add New Layer button (the first one) to create another layer. Repeat the action until you have five layers (
Background and another four).
To change the active layer (the one you draw on) click on it.
To open the Layer Properties window (name, opacity), double-click it.
Rename the layers to something meaningful, from bottom up, for example: Background, BaseMap, Colors, Borders, Labels.
Set the opacities of the BaseMap and Colors layers to something less than fully opaque (255 = fully opaque, 0 = fully transparent / invisible). I usually use 128 to 192 for the base map and 128 to 64 for the colors, with their sum equalling 256 (for example BaseMap - opacity 160, Colors - opacity 96).
You may later play with these values until the map looks right (at the end, when the map is almost ready).
Save the file again.
2.4. Importing the Base Map
Open the Base Map you have saved earlier.
Paint.net can keep several files opened at the same time.
You can see their
thumbnails in the upper part of the window, to the right of the
Menu and
Toolbars.
You may switch between the open files by clicking on the thumbnails.
With the base map file active (visible), select all the image (CTRL+A) and copy it to the
Clipboard (CTRL+C).
Close the base map file and leave it away. It will be no longer necessary (at least not before you decide to create another map using it.
In your layered file (the one you work on),
select the BaseMap layer.
Paste the copied base map into the layer (CTRL+V).
As the base map is larger (has more pixels) than your file, you are asked what to do. Choose wisely to
Expand Canvas in order to accomodate the larger image.
Save.
2.5. Cropping
Do you need all the map? Or are there unnecessary areas on some of the edges?
If everything looks fine, you may skip this step.
Click the
Rectangle Select tool in the upper-left
Tools window and select the desired part of the map.
Make sure that your selection contains everything you need in your map and crop it by pressing the
Crop to Selection button from the
Toolbar (the one next to the easily recognoscible
Paste button). Or press CTRL+SHIFT+X.
Save again.
Done.
In Part Three, we will really start to do some image editing. Next post.