Why is the resolution of my vertical image "different" than horizontal?

C

cinders

New member
I've read that the ppi in the metadata of the image has nothing to do with the actual resolution of the image. My camera (Nikon DSLR) will say a horizontal image is 300 ppi, but a vertical image is recorded with 72 ppi.

If I transfer the vertical image to a 300 ppi template, the image remains the same actual size. The image can still be published professionally.

So I'm content, technically. But no one seems to know why the camera (and mine isn't the only one) will say 72 ppi for vertical images. Anyone know?
 
I've noticed it too. Had D80, and now have a D90.

I think it's because of playback considerations. The LCD screen on the camera is horizontal (it's got more pixels along the horizontal axis than vertical). When it shows a vertical image it does so by making the top ends fit onto the horizontal LCD, thereby not using much of the pixels to the left and right, and essentially showing a smaller image.

Therefore the camera's build in software recognizes that a lower ppi is required. It is ppi, that is pixel density, not total number of pixels or resolution, which should remain the same.
 
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