Posted by Mike Hayes on May 24, 2015; 10:17pm
URL: https://forum.librecad.org/Scaling-imported-images-tp5711385p5711556.html

Like Armin said in his post above, if you reduce the size of the bitmap image you will reduce its quality. For example, if you halve the size of the bitmap image then every block of 4 pixels will be downgraded to a single pixel.

Your problem is similar to the one that occurs when tracing old architectural plans which have been scanned from paper copies.

The practical solution is to import the highest resolution version of the bitmap image that you posess into LibreCAD. This will preserve the maximum amount of detail and enable you to make the best quality trace.

After you have imported the bitmap, just ignore the scale for the time being and trace it.

Once you have a vector trace, you no longer need the bitmap and you can delete it from LibreCAD.

Then, knowing the real world size of a particular component of the drawing, you can use the scale command to accurately resize the whole thing.

Mike