Confused how to make your BMP correct sized when converting it with import-bmp?

First of all:
– Make your image 2 colored BMP, great tool for Windows, Linux and OS X is the old classic XnView – For colored images I suggest dithering the image to 2 colored image
– Make your graphics as library package (in Eagle), trust me, it’s worth it (you can make changes easily and don’t mess up your board since the graphic is a package)
– Use layer 25 (tNames) for your graphics. When you have added the package to your board, you can change it’s side by mirroring it.

Then the secret formula:

Scale factor for pixel = wanted graphic size / image size in pixels

For example if you want 204 pixel wide image to be 10mm, you enter 0.0490196078 as the scale. (10 / 204 = 0,0490196078).