I don`t have time to make a detailed tutorial with pictures right now so I`ll just write the steps and if you have any questions I could detail more.
You need to have Gimp installed:
https://en.wikipedia.org/wiki/GIMP
For the sake of the demonstration let`s say you`re trying to make cards for the French Renault AHN. You`ll have the following files:
Renault AHN l - the truck facing left
Renault AHN l+++ - shadow for the same direction
Renault AHN r - the truck facing right
Renault AHN r+++ - shadow for the same direction as above
In Gimp go to File->Open find the
Renault AHN l file and click open.
Right-click the file, go to Edit and click Copy. You can use keyboard shortcuts too, but I`ll stick to the mouse clicks here.
Then open the shadow for this file, namely
Renault AHN l+++. Right-click the file and go to Layer->Transparency->Color to Alpha. A small panel will appear showing you the preview. Normally the white color is selected by default so all you need to do when the panel appears is hit the OK button.
The shadow file will now contain alpha/transparency. Right click it and go to Edit->Paste. The image of the truck (which you`ve copied earlier) will appear on top of the shadow. Just click away to deselect it and this merges the two. You don`t need to adjust the position of the truck; it will automatically be pasted in the correct position (I`ve had some exceptions along the years though).
This is your left facing truck with shadow. Do the same thing with the files for the right facing image.
After you have the two, go to the main GIMP window and click File->New. A small panel will appear. Here you need to change both Width and Height values to be 296. Then click on Advanced Options and change the box
Fill with: from
Background color to
Transparency. Then hit OK. This is the card in which you`ll place the two truck images (by copy-pasting them in and positioning them one at a time, of course).
Now actually begins the tedious part since you need to place them correctly. I recommend you go to View->Zoom and choose 800% for example. You can chose some other zoom level, but you need one that allows you to discern the individual pixels. As you move your mouse on the image you`ll notice that in the bottom-left corner you can read the coordinates of each pixel. I prefer to start with the unit facing left (Renault AHN l+++ in this case) which should go in the top-right part of the card.
As a general rule, the botom pixel of the wheels/tracks should be at around height 92. As far as the horizontal position goes you may choose whatever you want, provided it stays in its side of the card (the width is 296 so the 148 pixel will be your dividing line).
After you`ve placed the left facing unit you need to place the right facing unit opposite to it. For both esthetic and practical reasons you should try to set the images to be symmetrical. Try to respect the same height point you chose for the other side and also find some sort of landmark to follow for the width (for example the number of pixels from the edge of the card to the end of the truck). It`s just math and patience basically.
When you finish the above you need to place the small cards in the lower half of the card. For this go to the window for
Renault AHN l+++ and right click it->Image->Scale Image. Change the
pixels option to
percent. Change the width from 100,00 to 50,00. On the
Quality Interpolation field change the
Linear to
Cubic (Best). At this point the Height value will also be automatically changed to 50,00 so you can just click the
Scale button. Do the same for the other image (Renault AHN r+++)
You need to place the small images in the card. The general rule is that the bottom pixel (for wheeled and tracked vehicles) should be 242. In terms of the horizontal you could follow the example of some already completed card to get an idea of where they should go.
When you`re done with this part just go to File->Save as..., choose a name and save the file as a
.png. That`s about it.
