I use photos from a digital camera and work with them in Photoshop/Lightroom. Today I again imported pictures from the camera into photos-app on my MacBook Pro, mid 2014, Yosemite 10.10.4/3 (I had the problem on both versions, stable and beta), and then, before I saw the export-option, copied the pictures and pasted them into Preview.

As a result, I noticed an extreme quality-loss, since the resolution always was 1024x768 by 72 pxi instead of 3072x1728 by 180 dpi (yes I know I stated different units pxi/dpi but that's the information I get from my software pix is preview, dpi is digital images, and I think there isn't much of a difference?).

I'm wondering where this comes from, also because exporting works fine, without quality-loss and I would like to know how I can see the dpi of an image with preview-app / information-option.

Thank you,


  • They are not the same. The DPI (dots per inch) is typically used to define the print quality.
    – Ruskes
    May 14, 2015 at 16:36
  • yes I know that they aren't exactly the same, but it doesn't make a difference in which unit I state them, since you can connect them, that's what I wanted to say.
    – Gabkano
    May 14, 2015 at 16:45
  • Accepted screen resolution is 72dpi - whether all screens still match that figure is less likely now than 10 years ago- however, the image would logically be reduced to 'screen quality' rather than print quality to display on screen. Presumably, the full res image is still in place for export. Why? Because things always did.
    – Tetsujin
    May 14, 2015 at 16:52
  • So your problem is (was) the copy and paste the pictures in to preview that resulted in quality loss? What did you use to copy/paste?
    – Ruskes
    May 14, 2015 at 17:08
  • well, yeah that's right, I'm just curious why copy+paste has so much quality-loss. I marked the photo in the photo-app, pressed cmd+c -> in preview cmd+n and after that, the image had the bad quality.
    – Gabkano
    May 14, 2015 at 17:31

1 Answer 1


The Preview does not lower the image quality, but will fit it in the given parameters.

If you use Preview to open a original image: Example:

5.5 MB file size with Dimensions of 3648 × 2736 pixels

Now open the Preview Tools - Adjust Size to see the current settings.

The default resolution is set to 72 which is standard for web applications.

In that window you can set it to the original size/resolution.

enter image description here

Now if you are using a copy/paste to move the image to Preview, the resulting quality will depend on the copy/paste settings. That can be found in the application it self.

  • where can I find the copy+paste settings?
    – Gabkano
    May 14, 2015 at 17:39
  • 1
    That would be completly new question you should ask, but for now, do a copy (of your chosen file) then go to Finder- Edit- Show Clipboard. How does it look ? crisp or already bad ?
    – Ruskes
    May 14, 2015 at 17:57

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