Some time ago a friend sent me some pictures of a printer expansion card for a brazilian ZX Spectrum. In order to produce a PCB layout for a clone of such board i needed some tool to make measurements based on a photo, and the choosen one was Google Sketchup.
Step 1: Importing the Image
Before importing the image click on the views button to select a front view.
To import an image, go to the chose the FILE->IMPORT menu option. Make sure you check the "Use as image" option. Sketchup can import several types of image, including JPG, BMP and PNG. Most digital cameras and scanners can provide a picture in such formats.
After you click in open, move the corner of the image to the origin and click the left mouse button once
Without moving the mouse, click the left mouse button again. The image will be outlined in blue.