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Printing precise AR markers

asked 2016-06-21 03:47:50 -0500

J. Romeo gravatar image

Hi all, I'm trying to implement a class that automatically generates markers to locate and identify specific objects by means of a label. The markers are going to be printed and it is mandatory that the printed marker size is known, so I can accurately locate the objects in 3D with a single image.

The obvious approach to me is to modify the image's dpi, but that not seems to be possible in OpenCV. The default dpi of 96 is too small for my application, since at that dpi the mm per pixel are about 0.4. I would need something like 0.1 mm/px.

Does someone know how to change an image's dpi in OpenCV? Have someone found another way to get the images to be printed in a more precise way than printing at 96 dpi?

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OpenCV has nothing to do with how the images are printed. OpenCV only creates images of a given resolution. Whatever you're using to print it controls the dpi and how the image is translated to the paper.

Tetragramm gravatar imageTetragramm ( 2016-06-21 22:16:02 -0500 )edit

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answered 2016-06-24 01:42:36 -0500

J. Romeo gravatar image

Thanks for the answer. What I really wanted was the users to forgive about printing options and to choose "real size (based on image dpi)".

As OpenCV doesn't manage this questions, I will get the work done by creating a high-res image and letting the user to choose the printing size... Basically a change in the user's manual :)


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Asked: 2016-06-21 03:47:50 -0500

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Last updated: Jun 24 '16