How to set resolution of image

Asked Jul 14 '19 at 17:01

Active Jul 14 '19 at 17:01

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I am using OpenCV to generate images with depth of 1 bit to cut in a laser cutter (Github repo here). I save them with:

cv2.imwrite(filepath, img, [cv2.IMWRITE_PNG_BILEVEL, 1])

Each pixel corresponds to 0.05mm (called "scan gap" in the laser cutter). A sample image has 300 x 306 pixels and appears in the laser cutter software (LaserCut Pro 5) with size 30 mm x 30 mm. This corresponds to a resolution of 254 pixels per inch and the uncommon value could be from the software. I want a size of 15 mm x 15.3 mm and want to set a higher resolution to achieve that. I could resize by hand, but if I make a mistake, the pixels are no longer exactly aligned with the scan gap of the laser, resulting in inaccuracies in the engraving.

Does OpenCV have a way to set the resolution or final size of the image?

asked Jul 14 '19 at 17:01

miguelmorin

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This should help... https://stackoverflow.com/a/50504361/2836621 – Mark Setchell Jul 14 '19 at 17:09
Yes, that's what I'm looking for. Do you want to write an answer or mark the question as a duplicate? – miguelmorin Jul 14 '19 at 18:07
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Not sure what to do as I'm not an official OpenCV gold badge holder. The main thing is that you are sorted out, so all is good! – Mark Setchell Jul 14 '19 at 19:57
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If you don't want to be reliant on other tools to change the **dpi**, you could read the OpenCV-generated file, look for and modify or add the `pHYs` chunk. It's not too hard... https://www.w3.org/TR/PNG-Chunks.html – Mark Setchell Jul 14 '19 at 21:41
Thanks, I will try both soon and feedback on the result. – miguelmorin Jul 15 '19 at 08:36

How to set resolution of image

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