Photoshop: I have a digital x-ray image that has a mm ruler in the image. How can I scale the image so when I print, it will measue 1mm on the paper?

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I have a digital x-ray image that has a mm ruler in the image. How can I scale the image so when I print it out 1mm will measue 1mm on the printed image? Thanks
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Dr. Kent Haynes

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Posted 2 months ago

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Kit Kerner

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Dr. I'm not a doctor and I rarely print my images anymore. I use Photoshop for a hobby. Here is my question back to you: You want the printed image to measure one MM? Or do you want the measurements to be included in the printed image, no matter the size of the image? This is interesting and I would like to assist. Good Luck! 
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Max Johnson, Champion

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You can set your photoshop measurements to mm by going to 
Edit->Preferences->Units and Rulers...

Then change the Rulers dropdown to Milimeters

If you don't have the rulers visible, you turn them on with View->Rulers

After that is set up you can at least compare the ruler in the image to the expected print size of the image.

I recommend starting a new document at 300 dpi in whatever print size you want, then placing the image into that new document. Then you can scale the image with Edit->Transform-Scale to get the ruler in the image to match the ruler in photoshop. 
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Tom Attix, Employee

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If you know that your scanned image is un-resized, then printing at the same dpi as the image should get you in the ball park.  To do this print at 100% (uncheck Scale to Fit Media) and select a page size that isn't borderless in Print Settings (choosing borderless can resize the image). This will probably get you close but my guess is you'll still need to resize +/- 1-2%.