I have the scan of a technical drawing. When I print out the image, it does not have the original dimensions. I therefore want to scale and print the image in such a way that a certain line in the drawing will have a specific length (i.e. 9 cm). Is there a simple way of doing this without a special program? I would like to use Preview or Photos (Mac) or Adobe Reader
The dimensions will remain the same if:
The scanner is declaring the resolution it is scanning, for example, 300PPI.
You are saving the image in a file format that preserves this little data, for example, TIF. Pdf can also save this data but depends if the scanner actually did send the info.
If when printing you are using a program that uses this information. Some simple programs have some "automatic" options, like using this declared PPI, or resampling the image to fit the page.
But there can be some issues, for example, the scanner is not that precise. It is a mechanical device, so some parts could slide a bit, changing the dimensions.